DE102016101005A1 - Device and method for computer tomographic measurement of a workpiece - Google Patents

Abstract

The invention relates to a method and a device for computer tomographic measurement of a workpiece (109), comprising at least a computed tomography sensor system and a turntable (103) with a turntable (104) rotatable about an axis of rotation (103b). The turntable (104) has an exchangeable interface (110) on which, manually or automatically exchangeable, optionally a workpiece holder (111) or an intermediate piece (106), which has one or more calibration bodies (108) and / or one or more drift bodies (108). contains, can be coupled.

Description

The invention relates u. a. to an apparatus and method for measuring geometric features on a workpiece by computer tomography.

The invention also provides methods for drift correction, verification of the specification and for calibrating the computed tomography sensor system.

A further subject matter is an invention which relates to a method for correcting temperature influences on dimensional measurements on a measurement object with a computer tomograph

Also subject matter is an invention which relates to an apparatus and a method for computed tomography, wherein optical components are used for imaging the optical radiation emitted by a scintillator onto an optical detector.

The invention also provides a method for computed tomography, in which the workpiece is rotated about a virtual rotation axis other than the mechanical axis of rotation and / or a region of interest tomography is performed.

Subject of an independent invention is a method for measuring workpieces with computed tomography, wherein material boundaries between different materials or materials and the surrounding medium such as air to be detected.

The subject matter of an independent invention is an apparatus and a method for generating an X-ray emitting focal spot, in particular a device for generating X-radiation.

The subject matter of an independent invention is a method for compressing volume data such as voxel data (voxel volume) of computed tomography. In particular, the method finds application in the storage and further processing of volume data to be used for the dimensional or geometric evaluation of surface data of workpieces. The method is also intended for applications in which individual areas inside the workpiece must be available for evaluation.

Subject of an independent invention is a method for determining contours or contour points from volume data of a computed tomography.

The subject matter of an independent invention is a method for determining and / or adjusting the focal spot size of an X-ray tube.

The subject matter of an independent invention is a method for determining and / or adjusting the focal spot size of an X-ray tube.

For the dimensional measurement of complex geometries (geometric features) different tactile, tactile-optical, optical or computer tomographic sensors (computed tomography or computed tomography sensors) are used. Preferably, these are operated in coordinate measuring machines (CMMs), sometimes also several sensors combined in one device (multi-sensor CMM).

Computed tomography for the dimensional measurement of workpieces is to be understood as meaning that a reconstruction of the volume information (voxel data or voxel amplitudes in the form of gray values) for the volume detected by the detector is performed from the set of two-dimensional radiographic images recorded in a plurality of rotational positions of a workpiece by means of a planar detector , where the voxel data is a measure of the local attenuation coefficients, and measurement points or surface measurement points are generated at material boundaries by surface extraction methods from the voxel data. Measurements on the workpiece or dimensions of features or structures on the workpiece can be determined from these surface measuring points, that is to say dimensional measurements take place. The surface of the workpiece is represented for example by networking the surface points in the so-called STL (Standard Triangulation Language) format.

A computed tomography or a computed tomography (CT) sensor system generally consists of a flat detector, a radiation source, preferably X-ray source, and a mechanical axis of rotation (turntable) for rotating the workpiece to be measured in the beam cone of the detected by the detector part of the radiation source emitted radiation. In kinematic reversal, however, it is also possible to arrange the workpiece firmly and to rotate the detector and radiation source around the workpiece.

The term mechanical axis of rotation serves merely to distinguish it from a mathematical axis of rotation, when a mechanical axis of rotation (also referred to as a turntable) always permits rotation about a mathematical axis of rotation. The use of the term rotation axis therefore refers to the mechanical axis of rotation associated mathematical axis of rotation, insofar as the context meant a direction is, and on the mechanical axis of rotation, insofar as a device is meant. The term mechanical axis of rotation denotes no restriction on the implemented within the axis of rotation guide principle between fixed and rotatable part of the mechanical axis of rotation. So it means both mechanically stored, as well as air-bearing, or otherwise such as hydraulically mounted, etc., mechanical axes of rotation. The mathematical axis of rotation is also called the physical axis of rotation.

In addition to area-wide detectors, line detectors are also used as detectors. These have only a single detector line. For complete recording of radiographic information of a spatially extended workpiece workpiece and detector must be placed in several along the direction of the axis of rotation (mathematical axis of rotation) shifted positions. The resulting increased expenditure of time is avoided by the use of area detectors. Nevertheless, the present invention or the teachings of the invention can also be implemented for line detectors. Instead of processing radiographic images, ie 2D images, the information recorded with the respective detector line is processed and also referred to as radiographic images for the sake of simplicity.

In order to perform dimensional measurements using computed tomography sensors with high accuracy, it is necessary that the components of computed tomography sensors, namely the X-ray source, in particular the X-ray emitting focal spot, the X-ray detector and the mechanical axis of rotation (turntable), with the Rotation of the workpiece to be measured relative to the X-ray source and X-ray detector takes place about an axis of rotation, while the rotation assume constant and known positions to each other.

The knowledge of the positions of said components relative to one another is necessary in order in particular to determine the imaging scale of the workpiece on the detector. The exact knowledge of the magnification is necessary to make accurate measurements. In particular for determining the imaging scale, there are several methods in which a calibrated or non-calibrated measuring body, in particular calibration balls, are used as the calibration body. One possibility is to compare the size of the image, in particular the diameter of a calibration sphere, in one or more radiographic images with the calibrated size, in particular the calibrated ball diameter. Another possibility using radiation images of a Einmesskörpers is to move it in a direction parallel to the detector plane or perpendicular to the average radiation direction of the detected by the detector portion of the X-radiation, this portion is referred to as measuring radiation, and the ratio of the in the Transition images detected shift with the real displacement of the Einmesskörpers. For this, the real displacement must be determined exactly. This is done, for example, by measuring axes, such as are available for example in coordinate measuring machines. A third possibility is to tomograph a calibrated in its dimensions Einmesskörper, for example, a calibrated in diameter measuring ball, and set the dimensions measured by the real dimensions, so the calibration data in proportion. The DE102014113977.1 describes a corresponding method using a Einmesskörpers having a plurality of features, the distance of the features is set in proportion.

Positional changes occurring after the determination of the magnification (drift) between the components of the computed tomography sensor system, in particular also during the rotation of the workpiece occurring position changes lead to errors in measurement. To correct these, several methods for drift correction exist. These are exemplary in the PCT / EP2015 / 051925 described. In this case, drift bodies are used whose position in the radiographic image is evaluated. As a drift body can also serve the workpiece itself, are absorbed by the transmission images in a significantly reduced number of rotational positions before the actual measurement, which are then compared with those recorded in the actual measurement in the same rotational position. It is also possible to detect the drift body in the radiographic images by placing it on the turntable, whereby, however, part of the measuring volume is no longer available for the workpiece, as a result of which workpieces with a lower magnification and thus lower accuracy must be measured. Fundamentally, in the described methods, on the one hand, the drift to the calibration state and, on the other hand, the drift during the rotation can be determined. In addition, methods are described how the determined drift can be corrected. A first possibility is to correct the position of the components, a second one to shift the transmission images relative to each other and to correspondingly correct the third one, the geometry vectors associated with the transmission images, which enter into the reconstruction.

To demonstrate that computed tomography sensors operate at the specified accuracy, characteristics such as the maximum allowable probing deviation and the maximum allowable length error are specified by the manufacturer as specifications. In order to prove, in particular, that the probing deviation does not exceed the maximum permissible value, ie to perform a verification of a specification, a calibrated test sphere must be measured by computer tomography as a calibration body, ie radiographic images recorded in several rotational positions, reconstructed into a volume data set (voxel volume) and surface points extract the volume data set for the dimensional measurement of the sphere.

A disadvantage of the previously known methods is that workpiece to be measured, drift body and used as Einmesskörper or Prüfkugel calibration individually consuming, especially time-consuming, must be placed one after the other on the turntable of the turntable and aligned. The only exception is the case that the drift body is firmly attached to the turntable, which however results in the above-mentioned disadvantages of the limited measurement volume. In addition, it is not possible to achieve an automation in that at least two of the following steps can be performed without user intervention: measuring the computed tomography sensors, checking the specification of the computed tomography sensors, measuring the workpiece by means of computed tomography sensors, determining the drift or during the measurement of the workpiece with computed tomography sensors.

An object of the present invention is to avoid the disadvantages of the prior art, in particular simple, fast, reproducible, in particular without manual alignment, and preferably also automatable to allow the various of the aforementioned steps, in particular a simple, fast and reproducible replacement To allow workpiece, calibration body or drift body.

To solve at least partial aspects u. a. proposed a device in which the turntable has an exchange interface to the manually or automatically interchangeable selectively a workpiece holder and an intermediate piece containing one or more calibration body and / or one or more drift bodies, can be coupled.

The present invention relates u. a. to a device for computed tomographic measurement of a workpiece, comprising at least a computed tomography sensor comprising an X-ray source, a surface extended X-ray detector and a mechanical axis of rotation (turntable) with a rotation about a rotation axis rotatable part (turntable), and at least one workpiece holder, the turntable directly or indirectly starting and comprises means for fixing the workpiece, wherein the device is adapted to receive radiographic images of the workpiece in a plurality of rotational positions about the axis of rotation and to reconstruct the radiographic images that detect the workpiece to a volume data set (voxel volume) and preferably surface points from the volume data set to the dimensional Extract measurement of the workpiece, wherein the device is characterized in that the turntable has an interchangeable interface on the manually or automatically interchangeable either the workpiece holder or an intermediate piece, which contains one or more calibration bodies and / or one or more drift bodies, can be coupled.

• 1. Nur der Werkstückhalter (gegebenenfalls mit eingelegtem Werkstück) ist an der Wechselschnittstelle angeordnet. Hierdurch steht das maximal mögliche Messvolumen zur Verfügung.
• 2. Nur das Zwischenstück ist an der Wechselschnittstelle angeordnet. Hierdurch ergibt sich die Möglichkeit, einen Kalibrierkörper oder einen Driftkörper abzubilden. Der Kalibrierkörper kann ausgebildet sein, als Einmesskörper zum Einmessen der Computertomografie-Sensorik oder als Prüfkugel zur Überprüfung einer Spezifikation. Es können auch mehrere Kalibrierkörper oder Driftkörper in einem Zwischenstück angeordnet sein. Zudem können mehrere unterschiedlich bestückte Zwischenstücke existieren, die an der Wechselschnittstelle befestigt werden können, also mit dieser koppelbar sind. Die Anordnung eines Driftkörpers ist dann sinnvoll, wenn die Drift zwischen dem Zeitpunkt direkt nach dem Einmessen und direkt vor oder nach der Messung eines Werkstücks ermittelt werden soll.
• 3. Das Zwischenstück ist an der Wechselschnittstelle angeordnet und an dem Zwischenstück ist der Werkstückhalter (mit eingelegtem Werkstück) befestigt. Für den Fall, dass das Zwischenstück einen Driftkörper enthält, ergeben sich dabei zwei Betriebsarten. Zum einen kann der Driftkörper dauerhaft in den Durchstrahlungsbildern zusammen mit dem Werkstück abgebildet werden. Zum anderen kann der Driftkörper vor oder nach der Messung des Werkstücks oder in ausgewählten Drehstellungen vor oder während der Messung des Werkstücks durch Bewegung des Drehtisches in Richtung der Drehachse in eine Stellung gebracht werden, in der die Abbildung in einem Durchstrahlungsbild erfolgen kann. Für den Fall, dass das Zwischenstück einen Kalibrierkörper enthält, ist die gleichzeitige Erfassung von Werkstück und Kalibrierkörper in einem Durchstrahlungsbild zwar möglich, aber wenig sinnvoll. Vielmehr ist es dann sinnvoll, vor oder nach der Messung des Werkstücks den Kalibrierkörper durch Bewegung des Drehtisches in Richtung der Drehachse in eine Stellung zu bringen, dass dieser erfasst wird um die Computertomografie-Sensorik einzumessen oder dessen Spezifikation zu überprüfen.

Optionally, this means that the change-over interface is designed to receive the workpiece holder, but also the intermediate piece, but in succession and not simultaneously. However, this does not exclude that the workpiece holder is attached to the intermediate piece, wherein the intermediate piece is attached to the exchange interface. This results in three basic options:

• 1. Only the workpiece holder (possibly with inserted workpiece) is arranged on the interface. As a result, the maximum possible measurement volume is available.
• 2. Only the spacer is located at the interface. This results in the possibility of imaging a calibration body or a drift body. The calibration body can be designed as a measuring body for calibrating the computed tomography sensor system or as a test ball for checking a specification. It is also possible to arrange a plurality of calibration bodies or drift bodies in an intermediate piece. In addition, several differently equipped intermediate pieces may exist, which can be attached to the change interface, that are coupled with this. The arrangement of a drift body is useful if the drift between the time directly after the calibration and directly before or after the measurement of a workpiece to be determined.
• 3. The intermediate piece is arranged on the exchange interface and on the intermediate piece of the workpiece holder (with inserted workpiece) is attached. In the event that the intermediate piece contains a drift body, this results in two operating modes. On the one hand, the drift body can be imaged permanently in the radiographic images together with the workpiece. On the other hand, the drift body before or after the measurement of the workpiece or in selected rotational positions before or during the Measurement of the workpiece are brought by movement of the turntable in the direction of the axis of rotation in a position in which the image can be made in a radiographic image. In the event that the intermediate piece contains a calibration, the simultaneous detection of workpiece and calibration in a radiographic image is possible, but not very useful. Rather, it makes sense then, before or after the measurement of the workpiece to bring the calibration by moving the turntable in the direction of the axis of rotation in a position that this is detected to measure the computer tomography sensors or to check its specification.

A device according to the invention is also characterized in that the intermediate piece is fixedly or detachably connected to a workpiece holder.

It is preferably provided that calibration bodies and / or drift bodies have a spherical shape at least in sections and / or are arranged along the direction of the axis of rotation.

The invention is also characterized in particular in that the intermediate piece has only a single drift body or only a single calibration body or only a single body which can be used as a drift body and as a calibration body.

It should also be emphasized that the turntable can be displaced at least in the direction of the axis of rotation by a distance so that calibration bodies and / or drift bodies can be positioned in and out of the area of the radiation emitted by the x-ray source (measuring radiation).

Preferably, the invention provides that the intermediate piece contains an opening, can be detected by the calibration body and / or drift body with an optical sensor, preferably image processing sensor, and / or with a tactile sensor and / or with a tactile-optical sensor.

• – vor der computertomografischen Messung ein mit dem Werkstückhalter verbundenes Zwischenstück eingewechselt wird, das während der computertomografischen Messung eingewechselt bleibt, oder
• – während der computertomografischen Messung in ausgewählten Drehstellungen ein vor der Messung eingewechselter Werkstückhalter ausgewechselt und das Zwischenstück vorübergehend eingewechselt und anschließend der Werkstückalter wieder eingewechselt wird.

Partial aspects of an object, the present invention solves essentially by a method for drift correction for a computed tomography, preferably using at least partially previously explained arrangement, wherein in a measurement, a workpiece to be measured between an X-ray emitting X-ray source and an X-ray receiving X-ray detector in a workpiece holder is arranged and radiographic images are recorded in several rotational positions (measurement rotational positions) of the workpiece, wherein before the actual measurement occurred and / or occurring during the actual measurement relative movements (drift) between the X-ray source, in particular the X-ray emitting focal spot of the X-ray source, and the X-ray detector and / or the workpiece with respect to a Einmesszustand be corrected by the position of a drift body detected in one or more radiographic images w ird, wherein the radiographic images or portions of these radiographic images that detect the workpiece are reconstructed into a volume data set (voxel volume) and surface points are preferably extracted from the volumetric data set for dimensional measurement of the workpiece, wherein the method is characterized in that a drift body is detected which is in an intermediate piece is included, wherein prior to the computed tomography measurement, the intermediate piece loaded, detects the drift body in one or more selected rotational positions and the adapter is replaced again, and / or either

• - Before the computer tomographic measurement, an intermediate piece connected to the workpiece holder is exchanged, which remains active during the computer tomographic measurement, or
• - Replaced during the computer tomographic measurement in selected rotational positions a substitute before the measurement workpiece holder and the spacer temporarily replaced and then the workpiece age is replaced again.

• – in den vom Werkstück aufgenommenen Durchstrahlungsbildern mit erfasst wird, und vorzugsweise in jedem dieser Durchstrahlungsbilder die Position des Driftkörpers ausgewertet und zur Korrektur der Drift verwendet wird, oder
• – nur in ausgewählten Drehstellungen durch Positionierung des Drehtisches entlang der Richtung der Drehachse in jeweils einem zusätzlich erfassten Durchstrahlungsbild erfasst wird.

In particular, the invention provides that a drift body contained in an intermediate piece connected to the workpiece holder

• Is detected in the radiation images recorded by the workpiece, and preferably in each of these radiographic images the position of the drift body is evaluated and used to correct the drift, or
• - Is detected only in selected rotational positions by positioning the turntable along the direction of the axis of rotation in each case an additionally detected radiographic image.

Preferably, it is provided that the drift body is detected only in selected rotational positions, wherein the selected rotational positions have a constant angular distance from each other, preferably the number of selected rotational positions at least 10, preferably at least 36, more preferably at most 100, is.

An object underlying the invention is also essentially achieved by a method for checking the specification, in particular probing deviation on a test ball, a computed tomography sensor system preferably with a previously explained device, wherein a calibrated test sphere is used as the calibration body, which is arranged between an x-ray emitting x-ray source and an x-ray receiving x-ray detector and recorded by the radiographic images in a plurality of rotational positions (measuring rotational positions) of the test ball in which the radiographic images are reconstructed into a volume data set (voxel volume) and surface points are extracted from the volumetric data set for the dimensional measurement of the test sphere, in particular the diameter and the shape of the test sphere, characterized in that the test sphere is arranged in an intermediate piece which overlies a change-over interface is exchanged, wherein preferably the intermediate piece is connected to the workpiece holder and for computer tomographic measurement of the workpiece, the test ball by positioning the dre htisches in one direction along the axis of rotation from the detected by the X-ray detector portion of the emitted radiation from the X-ray source (measuring radiation) is moved out.

The invention also relates to a method for measuring, in particular the geometry of the position of the components of the computed tomography sensors to each other and / or the magnification, a computed tomography sensor.

Partial aspects of a task, the present invention solves essentially by a method for measuring, in particular the geometry of the position of the components of computed tomography sensors to each other and / or the magnification, a computed tomography sensor preferably with a device described above, wherein as a calibration body a Einmesskugel, in particular uncalibrated calibration ball is used, which is arranged between an X-ray emitting X-ray source and an X-ray receiving X-ray detector and are recorded by the transmission images in a plurality of rotational positions and / or a plurality of translational relative positions to the unit of X-ray source and X-ray detector, wherein in Radiation images in each case the position and / or the diameter of the Einmesskugel is determined that is characterized in that the Einmesskugel is arranged in an intermediate piece, the üb He is exchanged an exchange interface, wherein preferably the intermediate piece is connected to the workpiece holder and for computer tomographic measurement of the workpiece, the test ball is moved by positioning the turntable in a direction along the axis of rotation of the detected by the X-ray detector region of the radiation emitted by the X-ray source (measuring radiation) ,

In particular, the invention is characterized in that the position of the calibration ball is determined in a plurality of translational relative positions, wherein the translational relative positions are arranged in a plane parallel to the detector plane or in a direction perpendicular to the average direction of the measuring radiation level, and from the ratio of or Distances in the radiographic images to the corresponding distances of the translational relative positions, which are preferably determined by the measuring axes of a coordinate measuring machine, the magnification of the computed tomography sensor is determined.

Preferably, the invention provides that the translational relative positions are recorded in two rotational positions rotated by 180 ° relative to each other and the distances in the radiographic images and the distances of the translational relative positions are respectively averaged.

It should also be emphasized that a plurality of intermediate pieces with differently sized drift bodies and / or calibration bodies, in particular test balls with different diameters, are available and the appropriate drift body or calibration body, in particular the suitable test ball, is selected depending on the present or set measurement volume.

Preferably, it is provided that the device according to the invention is integrated in a coordinate measuring machine, preferably integrated in a multi-sensor coordinate measuring device together with other sensors, preferably tactile, optical or tactile-optical sensors.

The invention is also characterized in that the method is operated in a coordinate measuring machine, preferably in a multi-sensor coordinate measuring device together with other sensors, preferably tactile, optical or tactile-optical sensors is used.

In a development, it is also provided that a first drift body is provided in a replaceable intermediate piece and at least one further drift body originates from the turntable, in particular the turntable. The further drift body can thereby be used, for example, to determine the drift to the calibration state, and the first drift body is exchanged with the workpiece holder, for example, and is used to determine the drift during the computed tomographic measurement of the workpiece.

Depending on the coefficient of linear expansion and the present temperature, changes in the length of the measured object intended for measurement occur with temperature changes. Measurements made with a computer tomograph are corrected according to the prior art with respect to these temperature influences, for example by correcting the radiographic images according to the temperature at the time of their recording, such as the DE102013107368.9 the applicant describes.

The disadvantage here, however, that in the radiographic image different materials for which different corrections are to be provided due to different coefficients of linear expansion, not recognizable or the material is generally not assignable, since the information present in the radiographic image in addition to the material of the geometry, in particular in the present rotary position irradiated material length, depend. Thus, a correction of temperature-related influences for workpieces made of several materials (multi-material parts) is not possible.

A further independent object of the present invention is therefore to avoid this disadvantage, so that temperature-induced changes in length of the measurement object can be corrected even in the presence of different materials.

This object is essentially achieved by the present invention in that the size and preferably also the position of the individual voxels are corrected as a function of the coefficient of linear expansion, which comprises the material that can be assigned to the voxel. Similar to the change of voxel size and voxel position, the voxel data, ie gray values of the voxel and its environment, can be adjusted accordingly.

The present temperature must be determined during the acquisition of the 2D radiographic images. By means of a temperature sensor, for example, the temperature of the measurement object is determined directly or the measurement volume surrounding the measurement object, that is to say the measurement area detected by the computer tomograph. The temperature detected during the acquisition of the 2D radiographic images is then used for the correction.

The present invention thus also relates to a method for correcting temperature effects on dimensional measurements on a measurement object with a computer tomograph, preferably X-ray computer tomographs, particularly preferably in a coordinate measuring machine integrated CT, at least consisting of at least one radiation source, preferably X-ray tube, a mechanical rotation axis for rotation a measurement object, and a detector, preferably an X-ray detector, wherein the measurement object is irradiated in several rotational positions of the radiation of the radiation source and respectively associated 2D radiographic images are taken, from which three-dimensional volume information in voxel format (so-called voxel volume) are calculated by means of reconstruction, wherein in this voxel volume data (voxel data, for example in the form of gray values) are included for local beam absorption, and wherein from the voxel data, preferably in the area The size (voxel size or voxel edge length), preferably the size and position (voxel position), of the voxel volume voxel is corrected as a function of the prevailing temperature and the coefficient of linear expansion associated with the respective voxel by a corrected voxel volume Alternatively, this correction of the voxel sizes, and preferably the voxel positions, is implemented by adjusting the voxel data of the voxel and the neighboring voxels.

In particular, the invention is characterized in that the coefficient of linear expansion associated with the respective voxel is determined from the assigned material, the material being selected from the gray value of the voxel and / or the gray values of adjacent voxels and / or the target data, for example from a model such as CAD- Model, is determined, wherein preferably when using the gray values of the gray values or gray scale ranges in each case a material is assigned.

It should also be emphasized that adjacent voxels are shifted depending on the voxel size change to determine the corrected voxel position.

Preferably, the invention provides that the corrected voxel volume is converted into a uniform voxel grid by means of resampling, preferably by the use of interpolation methods, wherein a voxel grid with a lower voxel edge length is preferably produced.

Another independent invention relates to a computer tomograph, in particular to a device for receiving a plurality of radiographic images of a measurement object for performing a computed tomography, wherein the structure of a corresponding detector of structurally separated scintillator and optical detector according to the DE102013108367A1 the Applicant is realized. On the full content of DE102013108367A1 These are the known methods of US 7,400,704 . US 6,353,657 . US 6,483,893 and US 7,286,640 as relevant status of the art, therefore, reference is hereby made. The DE102013108367A1 teaches, among other things, that the area of the scintillator detected by the optical detector should be adjustable in size and position, the resolution should be adapted and several areas should be detectable by moving the optical detector and the scintillator relative to one another. It also mentions the use of optical components to image the optical radiation emitted by the scintillator, details of which are given only in that a shift of the lens groups can be made to adjust the working distance and the optical magnification. It is not described which properties correspondingly suitable optics should have or which design and whether other optical elements should be used.

The problem with the emission of optical radiation by the detector is the large emission angle (Lambert radiator). As a result, a large light output and thus a high signal-to-noise ratio can only be achieved if large lenses or optics or other optical components as completely as possible forwarding optical components are used and in particular are arranged close to the scintillator. In addition, a high imaging quality or low aberrations of the optical components is required to realize accurate measurements, making them very expensive or not at all available.

A further independent object of the present invention is therefore to propose cheap and available optical components which are suitable for imaging the radiation emitted by a scintillator onto an optical detector. In addition to the structure necessary for this, if necessary, methods are needed to correct occurring aberrations.

This object is achieved by the present invention essentially in that are used as optical components parabolic mirror, Fresnel lenses and / or fiber optic taper, which are preferably optimized to achieve the highest possible light output, aberrations may occur with appropriate methods such as Distortion correction, distortion correction and / or light-dark correction are corrected.

The present invention therefore also relates to a device for recording a plurality of radiographic images of a measurement object for performing a computed tomography, wherein radiographic images in a plurality of rotational positions, adjustable by a rotating device such as mechanical axis of rotation, in which the measurement object and a computed tomography sensor are arranged rotated relative to each other , Preferably, the measurement object is rotated, are receivable, wherein the computed tomography sensor at least consists of a radiation source such as X-ray tube, at least one scintillator and at least one surface area performed, optical detector, the radiographic images of at least one optical detector can be received and reconstructed to a voxel volume are from which preferably surface points can be determined at material transitions, wherein the output from the scintillator optical radiation at least partially from the zumin at least one optical detector is detectable, and wherein the computed tomography sensor is preferably integrated in a coordinate measuring machine, wherein preferably means for adjusting the size and / or position of the detectable by the optical detector, the optical radiation emitting first region and / or other areas of the scintillator are present , Preferably means, with which the optical detector and the scintillator are displaceable relative to each other, which is characterized in that between the scintillator and the optical detector one or more optical components are arranged, which direct the radiation emitted by the scintillator optical radiation to the optical detector wherein at least one of the optical components is optimized to achieve the highest possible light output with respect to the emitted from the scintillator optical radiation, said or these optical components in particular have or have aberrations RFEN. As a result, inexpensive particularly large optics such as lenses, mirrors or taper can be used.

In particular, the invention is distinguished by the fact that parabolic mirrors, Fresnel lenses and / or glass fiber tapers are used as optical components.

According to the invention, it is also provided to use at least one further optical component that at least partially corrects the aberrations.

The present invention also relates to a computed tomography method for dimensional measurements on a measurement object with a previously mentioned device, wherein the aberrations occurring due to the properties of the optical components used are at least partially corrected, preferably by at least one distortion correction and / or distortion correction and / or or chiaroscuro correction is performed. Corresponding methods are known from image processing or microscopy and the deviations to be corrected are usually calibrated once, ie before the actual one Measurement determined, and applied for the correction of the measurement. The application of further additional corrections is provided if the optical components used have corresponding aberrations. The at least partial correction of the aberrations can be done alternatively or additionally by further correspondingly suitable optical components.

Another independent invention relates to a computed tomography and a computed tomography method according to the EP2399237 wherein the workpiece is rotated about a virtual axis of rotation other than the mechanical axis of rotation. Alternatively, the application of the teaching according to the invention can also be used in a region of interest tomography, in which the workpiece is rotated about the axis of rotation of the mechanical axis of rotation. In both methods, it is preferred to use two-dimensionally extended detectors. It is disadvantageous that artefacts, in particular stray radiation, are produced by the computed tomography image, which in particular are incorporated into the measurement result due to the extent of the detector in the direction of the axis of rotation.

A further independent object of the present invention is, therefore, the artefacts detected due to the expansion of the detector in the direction of the axis of rotation, such as scattered radiation, in a region of interest tomography, in particular in a computer tomography in which the workpiece is one of the mechanical axis of rotation is rotated different virtual axis of rotation, to avoid.

This object is essentially achieved by the present invention in that a line-shaped detector or only a two-dimensional detector having a plurality of adjacent lines is used, wherein, for example, a helical tomography is performed or the detector or the detector area used piecewise displaced in the direction of the axis of rotation to capture two-dimensional radiographic images.

• – Röntgenquelle und/oder Strahlendetektor relativ zum Messobjekt, und vorzugsweise zur mechanischen Drehachse, wobei das Messobjekt fest auf der mechanischen Drehachse angeordnet ist, positionierbar sind, und wobei die Drehung des Werkstücks mithilfe einer Kombination aus rotatorischer und translatorischer Relativbewegung zwischen Werkstück und Detektor, um eine von der physikalischen Drehachse verschiedenen Drehachse erfolgt, und/oder
• – lediglich ein senkrecht zur Drehachse begrenzter Ausschnitt des Messobjekts in allen Drehstellungen vom Detektor erfasst wird,

dass sich dadurch auszeichnet, dass als Strahlendetektor verwendet wird ein Zeilendetektor oder eine Zeile eines flächig ausgeprägten Detektors oder mehrere benachbarte Zeilen eines flächig ausgeprägten Detektors, jedoch in einer in Bezug auf alle Zeilen eingeschränkten Anzahl, bevorzugt maximal ein Viertel, besonders bevorzugt maximal ein Hundertstel aller Zeilen oder vorzugsweise maximal 10 Zeilen, wobei vorzugsweise eine Helixtomografie durchgeführt wird oder wobei der Detektor bzw. der verwendete Detektorbereich stückweise in Richtung der Drehachse versetzt werden, um zweidimensionale Durchstrahlungsbilder aufzunehmen.The present invention thus also relates to a computed tomography method for dimensional measurements on a measurement object with a computed tomography sensor system, comprising at least one radiation source such as an X-ray source and a radiation detector, wherein the measurement object is rotatably arranged on a mechanical axis of rotation between the X-ray source and the radiation detector and wherein Transmitted radiographs are recorded in different rotational positions of the workpiece and combined in particular to be reconstructed, wherein

• X-ray source and / or radiation detector relative to the measurement object, and preferably to the mechanical axis of rotation, wherein the measurement object is fixedly arranged on the mechanical axis of rotation, are positionable, and wherein the rotation of the workpiece by means of a combination of rotational and translational relative movement between the workpiece and the detector a rotational axis different from the physical axis of rotation takes place, and / or
• - Only a limited perpendicular to the axis of rotation cutout of the measurement object is detected in all rotational positions by the detector,

that is characterized in that is used as a radiation detector, a line detector or a row of a flat detector or more adjacent lines of a flat detector, but in a limited with respect to all rows number, preferably a maximum of a quarter, more preferably a maximum of one-hundredth of all Lines or preferably a maximum of 10 lines, wherein preferably a helical tomography is performed or wherein the detector or the detector area used are piecewise offset in the direction of the axis of rotation to receive two-dimensional radiographic images.

Subject of an independent invention is a method for measuring workpieces with computed tomography, wherein material boundaries between different materials or materials and the surrounding medium such as air to be detected.

In the known methods for the determination of material boundaries, in most cases, fixed threshold values are used to determine the material boundary, as described, for example, under the technical term marching cube in the German patent application no US4710876 is described. As a result, only the boundary between a combination of two materials or material with air can be determined. Not solved is the problem that the thresholds between different materials and air or different materials differ from each other. The use of a fixed threshold would cause material boundaries offset from one another to be recognized twice or even several times.

The EP1861822 describes a locally acting method, in which the course of the gray values through the surface between a material and the air is examined and determined on the basis of this course, for example, inflection point and at the point of the inflection point, a surface point is calculated.

Method for determining material boundaries in sectional images through the voxel volume For example, in the WO2012152738A1 described.

Another object of the present invention is therefore to automatically detect the surfaces between different materials or materials and the surrounding medium such as air in the presence of multiple materials within the range examined or measured by X-ray computer tomography. In particular, it is an object of the invention to recognize potentially multiple present recognized surface boundaries and to select the appropriate surface boundary.

The invention provides for the solution u. a. a method for measuring workpieces consisting of at least two different materials with X-ray computed tomography, wherein volume elements (voxels) having voxel volume is generated by the local X-ray absorption (local attenuation coefficients), preferably in the form of gray values, associated with the voxels before is characterized in that the material boundaries between the materials and / or between the materials and the surrounding medium, such as air, are determined and from this the geometric description of the surfaces, in particular point cloud of existing from the respective components of the workpiece components are determined in whole or in part ,

As ambient medium air is preferably provided. However, the invention equally applies to other surrounding media such as liquids or other gases. Even if air is dealt with in the further description, other surrounding media are alternatively covered by the teaching.

The description of the surface is preferably in the form of measuring points on the surface or in the form of so-called point clouds. The presence of different materials may also mean, for example, that the workpiece consists of several components, the components being made of different materials. An exemplary workpiece is a printed circuit board, which consists of carrier material, such as plastic or metal-coated material, and printed conductors, and other components such as solder or plastic or other covering materials.

Common combinations are plastics with metals. Therefore, according to the invention, not only the material boundaries of components which are subject to one another should be recognized, but also within assemblies or within a single workpiece, which consists of different materials.

In particular, the invention is characterized in that the boundary to the adjacent subcomponents and / or to the surrounding medium, in particular to the surrounding air, is determined for each subcomponent consisting of the individual materials.

It is preferably provided that the material boundaries determined for the various subcomponents are combined to form a complete geometric description of the workpiece.

The overall geometric description of the workpiece includes all detected transitions between the materials or the individual materials and air for which measurement points are determined, with the measurement points being able to be evaluated as a common measurement point cloud.

In particular, the invention is characterized in that, when joining the surface descriptions describing the material boundaries of different subcomponents, double or multiple surface descriptions for an interface are combined or replaced by selection of one of the surface descriptions.

A surface description for a material boundary arises, for example, in that a parameter is defined for the materials or combination of material present at the respective material boundary and the surrounding medium such as air. This parameter may, for example, be a threshold value for a gray value of the information present in the voxels. By way of example, by means of this threshold value and the aforementioned marching cube method, the entire voxel volume can be examined for the occurrence of corresponding gray values. At the points where this gray value (threshold value) occurs, a material limit is detected. However, the course of the gray values between two materials through a material boundary is continuous and not erratic. As a result, the various materials are assigned continuous gray scale ranges between the threshold values of the various surface descriptions of the boundaries to the other materials or the surrounding medium, such as air. When specifying a threshold value for a defined material combination, for example material 1, the average gray value 200 and material 2 has the average gray value 100, wherein the gray value 150 is set as the threshold value by way of example, the threshold value occurs not only between these two materials, but also by way of example between two materials with the mean gray values 200 and 10, but here not at the correct point of the material transition, but spatially offset. For the correct threshold value between, for example, the materials with the average gray values 200 and 10, ie 105, the correct material limit results additionally. So there are duplicate surface descriptions. Another example of duplicate or multiple surface descriptions can be found in the exemplary embodiments.

Preferably, the invention provides that the material limits for the subcomponents are each successively determined for the different material combinations and for the combinations between the individual materials and the surrounding medium such as air and the parameter describing the material combination is a threshold for the determination of the material boundaries.

In particular, therefore, a threshold value is determined per material combination and per combination between the various materials occurring in the workpiece and the surrounding medium and, as explained above, surface or double surface descriptions for the corresponding interface may occur at individual material boundaries.

It should also be emphasized that this threshold value is used for the subvoxel-accurate determination of the position of the material boundary by interpolating between adjacent volume elements (voxels).

The subvoxel-accurate determination is exemplary for the marching cube algorithm. According to the invention, however, alternative approaches to subvoxel-accurate determination are provided.

The invention is also characterized in that material boundaries are described by point clouds, wherein the parameters of the different material combinations and the various materials occurring are determined with the surrounding medium such as air, and in a second step for each area of the surface description a fine selection of the optimum surface descriptions based on the locally occurring material combinations.

The fine selection of the optimal surface description includes the replacement or removal of duplicate or multiple surface descriptions.

In particular, the invention is characterized in that these points are assigned to the material boundary forming or comprising volume elements (voxels)

This means that for the calculation of a point, all the volume elements lying around the material boundary, that is to say these encompassing or forming the material boundary, or their position and / or gray value, are used for the determination of the surface point. For example, the location and gray value enter into the aforementioned interpolation, as described for subvoxeling.

According to a proposal to be particularly emphasized, it is provided that the determination of the inflection point of the intensity profile of the volume elements (voxels) takes place at the material boundary.

The intensity profile of the volume elements at the material boundary relates in particular to the course through the material boundary. Corresponding courses are investigated, for example, along lines which pierce the surface perpendicularly or almost perpendicularly, that is to say the material transition. The volume elements surrounding the line are preferably additionally used. The direction for the corresponding lines is derived from the surface description which is at least roughly determined by means of the threshold values.

It should be particularly emphasized that the threshold values for the material boundaries that occur are determined from the local attenuation coefficients of the volume elements (voxels) forming the material boundary.

Furthermore, the invention is characterized in that areas are determined in the sectional images or in the voxel volume for determining the threshold values by the user.

The sectional images are generated by cutting the volume information of the voxel volume and displayed for example on a screen. An area may be, for example, a measurement window. Regions of a volume can be selected for example on the basis of a 3D representation. This can include, for example, a cuboid or the narrowing of the corresponding axis coordinates. Other, for example, more complex geometries for the areas are also provided.

In particular, the invention is characterized in that for determining the gray values necessary for determining the threshold, the user defines areas defined for each material in sectional images or in the voxel volume within the material boundaries.

In this way, a gray value assigned to the material, for example the previously mentioned average gray value, is assigned to the individual materials.

For the determination of the gray values necessary for determining the threshold, it is preferably provided that the user can define an area in a sectional image or in the voxel volume for each border crossing between materials or material and the surrounding medium, such as air.

The result of the threshold value determinations are the individual threshold values for determining the transitions between the materials or the surrounding medium, such as air, which are used for the aforementioned determination of the material transitions.

In particular, the invention is characterized in that the areas are determined in a learning process and later processed automatically in workpiece coordinates.

Preferably, the invention provides that a histogram of the X-ray computed tomography volume (voxel volume) of the workpiece is used to determine, preferably automatic determination, of the parameters necessary for determining the material boundaries.

The use of a histogram allows in particular the automatic determination of the parameters for the determination of the material boundaries. According to the invention, however, it is also provided that corresponding areas of the histogram are selected or at least limited by user intervention. This makes it possible for the user to remove, for example, areas from the histogram, which no material combination can be assigned. Alternatively, a corresponding selection is also possible by means of a filtering such as low-pass filtering, as explained below.

In particular, the invention is characterized in that the histogram used to automatically determine the parameters necessary for the determination of the material boundaries is generated from a low-pass-filtered X-ray computed tomography voxel volume.

In the determination of the gray values associated with the materials or the surrounding medium, such as air, in the histogram, the gray values are weighted according to their frequency of occurrence (class frequency), for example by the display width of a gray value class in the histogram as a function of the number of gray values in the respective class (class frequency) is scaled, for example broadened, in order to improve the recognizability of significant differences in the histogram.

When displayed in histograms, gray values are often combined into so-called classes. The width of such a class denotes the gray scale range encompassed by that class. The number of gray values occurring within the class is called class frequency. The recognizability of significant differences in the histogram has the effect that gray value classes with a low number of occurring gray values, ie low class frequencies, are scaled slightly and thus can no longer be significantly identified in the histogram, or have no strong or no influence in a fitting step wherein the fitting is preferably performed over the entire histogram range. In contrast, areas with high class frequencies are more heavily involved in the fitting step, since the high number of gray levels in the class results in a correspondingly high scaling. For the corresponding adaptations, the histogram is preferably subdivided into partial regions, the partial regions each containing only the gray-scale classes assigned to one of the materials or the surrounding medium. Corresponding segmentations are possible, for example, in that all maxima and minima of the histogram are determined in a first step, and then regions around the maxima are defined, which are evaluated for the determination of the gray value to be assigned. The width of the areas is determined, for example, depending on the class frequency or depending on the minimums occurring. The segmented areas are then used for the maximum search. Corresponding methods for maximum search are, for example, the method of the photometric center, wherein preferably the data used for the maximum search are prefiltered or alternative edge-finding algorithms such as Laplacian operators are used.

It should also be emphasized that in order to determine the threshold values and / or surface descriptions, the maxima and minima of the histogram of the gray values of the voxels of the voxel volume are determined and used.

According to a particularly noteworthy proposal, it is provided that for the determination of the surface descriptions the minima and maxima of the histogram (hereafter original histogram) are used to generate a segmented voxel volume by defining the minima of the histogram as the class boundaries of a second histogram (working histogram) and all Gray values within a class are the maximum Gray value, preferably determined by a method for determining the maximum such as the method of the photometric center, assigned to the class and the volume elements (voxels) of the voxel volume from which the original histogram was generated (hereafter original volume) are copied into a second voxel volume (hereafter referred to as working volume) and then obtain the determined maximum value of the corresponding gray value class of the working histogram.

Furthermore, the invention is characterized in that the gradient field is determined from a given voxel volume in order to make a rough determination of the position of the surface descriptions of the boundary transitions between the materials and / or between the individual materials and the surrounding medium such as air.

A gradient field is a representation of the voxel volume, in which, instead of the voxel values (gray values), the voxels are assigned the gradients, ie differences or derivatives to the gray values of the neighboring voxels. In this case, a simple, ie a voxel comprehensive or multiple voxels comprehensive neighborhood can be considered. For example, the differences or derivatives to the multiple neighbor voxels are averaged to determine the respective gradient.

In particular, the invention is characterized in that methods for maximum search, such as the method of the photometric center, and / or methods for filtering, such as the Laplace operator, are used to automatically determine the parameters necessary for determining the material boundaries.

• – abschnittsweise um die Punkte der mehrfachen Oberflächenbeschreibungen definiert werden und
• – innerhalb der Suchbereiche jeweils vorzugsweise der Mittelwert oder der Mittelwert aus der Differenz des Maximums und Minimums der Grauwerte des dem Suchbereich zugeordneten Voxelvolumens gebildet wird und
• – die Differenz zwischen dem Mittelwert und dem den Punkten zugeordneten Schwellwerten gebildet wird und
• – die Punkte derjenigen Oberflächenbeschreibung zur weiteren Verwendung ausgewählt werden, die die kleineste Differenz aufweisen,

wobei vorzugsweise der Suchbereich so festgelegt wird, dass senkrecht zur Oberflächenbeschreibung Änderungen der Grauwerte im zugeordneten Voxelvolumen kleiner, bevorzugt mehrfach kleiner, als eine Mindeständerung sind, und wobei bevorzugt der Suchbereich tangential zur Oberflächenbeschreibung zumindest einen Punkt pro vorliegender Oberflächenbeschreibung einschließt.Particularly noteworthy is that for the selection of the surface description to be used in the presence of multiple surface descriptions search areas, such as volume areas such as cuboid,

• - section by section around the points of multiple surface descriptions are defined and
• Within the search areas, preferably the mean value or the mean value is formed from the difference of the maximum and minimum of the gray values of the voxel volume assigned to the search area, and
• The difference between the mean value and the thresholds associated with the points is formed, and
• The points of the surface description are selected for further use, which have the smallest difference,

wherein preferably the search range is determined such that, perpendicular to the surface description, changes in the gray values in the assigned voxel volume are smaller, preferably several times smaller, than a minimum change, and wherein preferably the search range tangent to the surface description includes at least one point per present surface description.

The selection of the surface description, more precisely the points of the surface description, is only necessary if there are multiple surface descriptions in a respective region or section, for example around a point or in a multi-point section. As a section, the direct environment, for example cuboid in space, of a single point is preferred. For each point, it should therefore be checked whether there are points of further surface descriptions in the environment from which the correct one is selected. The environment is therefore examined for each point by defining search areas around each point individually or several points at a time. In each case, the mean value of the gray values of the voxels in the search area is determined in the search areas in order to obtain an at least rough estimate for the correct threshold associated with the respective material transition. For this purpose, the search area perpendicular to the material transition, ie the surface or surface description must be large enough to completely cover this and to capture at least a small area in each case in the interior of the two materials of the material transition, for the thus assigned to the respective material gray value in the Voxels present. This presence is recognized by the fact that the gray value no longer changes significantly if the change is in particular smaller than a minimum change or several times smaller than a minimum change. Tangential to the material transition, the search area should include the points of all present surface descriptions for the respective section, ie at least one point per surface description. After determining the estimated value for the threshold value, the difference between this average value and the threshold values assigned to the points in the search range is formed. The nearest average threshold identifies the point that originates from the proper surface description and must be reused. If several points of a surface description with an associated threshold value lie in the search area and the assigned threshold value has the smallest difference to the mean value, then all points assigned to this threshold value are also selected.

Furthermore, the invention is characterized in that, to determine the present surface descriptions starting from the first surface description, preferably the surface description with the highest threshold, search beams perpendicular to Surface description are set and in the direction of the decreasing gray values or negative gray scale gradients along the search beams, the gray values are compared with the previously determined thresholds.

This alternative or additional procedure ensures that the corresponding points of further surface descriptions can be quickly found and assigned to each point. Starting from the surface description with preferably the highest associated threshold value, the voxels along the search rays, preferably again up to a presence of no more significant changes in the gray values in the preferred two direction, starting from the highest threshold only in the direction of decreasing gray values or negative gray scale gradients, the gray values compared with all existing thresholds. If matches or approximately the same values occur, a point of the surface description assigned to the threshold value must be taken into account. Found points are marked and excluded from the search on the basis of other surface descriptions and then the procedure for the surface description, ie the points of the surface description, repeated with the next or next lower threshold, respectively, until all points are assigned.

It should also be emphasized that of a given volume in the image space for the determination of the average gray values of the various occurring in the workpiece materials and / or the surrounding medium such as air and / or thresholds for the surface descriptions of the border crossings, between the different materials and / or between the individual materials and the surrounding medium, such as air, a 3D Fourier transformation, for example Fast Fourier Transformation (hereinafter FFT), of this voxel volume is performed and this voxel volume transformed into the frequency domain is trimmed and subsequently transformed back into the image space.

According to a proposal to be particularly emphasized, it is provided that the frequency areas of the spectrum transformed into the frequency space are cut out, for example high-frequency portions of the spectrum (low-pass effect) and / or low-frequency portions (high-pass effect), and then transformed back into the picture space.

A low-pass effect can be achieved, for example, by extracting high-frequency portion of the spectrum in the frequency domain and then subtracting it from the original spectrum.

Furthermore, the invention is characterized in that the volume transformed into the image space is used to generate a histogram for determining the gray value average values and / or the threshold values for determining the surface descriptions and / or for segmenting the volume transformed into the image space.

In particular, the invention is characterized in that as a preparation for determining the surface descriptions of the border crossings between the different materials of the workpiece or between the individual materials and the surrounding medium such as air, a homogenization of the gray values of the voxel volume is made by a mask volume is generated is a copy of the volume of the voxel and is removed from it by the iterative coarse surface description of the material boundaries, which are located in a defined area around the material boundary and involved in the material boundary volume elements, preferably iteratively using a filter, preferably "shrink" filter or "blow" filters to produce a voxel volume containing only the volume elements within the surface descriptions, which is then used to translate all gray levels of the volume elements using a filter kernel in the mask volume with too large a difference to a threshold previously defined to be replaced by another value, for example by the average of the gray values of the surrounding voxels or a fixed gray value, and then, using the original volume used for generating the mask volume and the mask volume even to produce a homogenized total volume.

A "shrink" filter is known as part of a "shrink and blow" filter used in image processing and replaces a cube of odd edge length in voxels in a previously defined filter region, for example in the voxel volume Value in the middle of the environment through the minimum (shrink filter) or maximum (blow filter) of all gray values of the voxels in the filter area. To generate the mask volume from the original voxel volume, the "shrink" filter (if surrounding medium has a lower absorption coefficient than material) or "blow" filter (if surrounding medium has a higher absorption coefficient than material) is applied to the original voxel volume.

The subject of an independent invention is an apparatus and a method for Generation of an X-ray emitting focal spot, in particular a device for generating X-radiation.

In the known devices for generating X-rays, the vacuum chamber of an X-ray tube, in which the means for generating and deflection of an electron beam are contained on a target, is completed by the target. The target has a sufficient thickness of at least a few hundred microns, which on the one hand a sufficiently strong vacuum of, for example, about 10e-6 mbar can be closed and on the other hand, in conjunction with the appropriate choice of materials, the electron beams are absorbed. The target consists at least of a substrate which is coated over a large area on the inside with a layer, such as a tungsten layer, which generates X-rays upon irradiation with electron beams. Corresponding substrates are made for good dissipation of the resulting heat, for example, diamond and have a thickness of about several hundred micrometers. The X-ray generating layer consists, for example, of a tungsten layer of a few micrometers in thickness. Other material combinations for substrate and layer are also conceivable and provided. The disadvantage here is that the size of the area emitting the x-rays, also called focal spot, is determined by the focusing of the electron beam on the x-ray generating layer. As a result, it is not possible to produce arbitrarily small focal spots, since a corresponding focus can only be achieved with a certain accuracy. In addition, corresponding means for focusing the electron beams are costly. Small focal spots are required, for example, for computer tomography, in particular for computed tomography for the dimensional measurement of workpieces or workpiece features.

The present invention therefore also relates in particular to the use of the device according to the invention and the method according to the invention in a computer tomograph for workpiece inspection and particularly preferably for the dimensional measurement of workpieces or workpiece features, in particular in a coordinate measuring machine containing a computer tomograph, in particular multisensor coordinate measuring machine, or by Coordinate measuring machine formed by computer tomography.

The above-described construction of an X-ray tube refers to an X-ray tube with a so-called transmission target. However, the invention is not limited to transmission targets. Likewise, the application of the teaching of the invention is also provided for so-called reflection targets. In these, the electron beam strikes the X-ray generating layer at a predefined angle of about 30 to 60 degrees and the X-radiation is emitted on the same side of the layer, also at a predefined angle. This is usually a separate exit window for the completion of the vacuum in the vacuum chamber of the X-ray tube.

A further object of the present invention is to realize the smallest possible focal spots, in particular almost circular focal spots smaller than 1 micrometer in diameter, preferably smaller than 0.5 micrometer diameter, more preferably smaller than 0.1 micrometer diameter for the generation of X-radiation , Deviating from the circular shape, focal spots of other external geometries are also meant in the context of the invention, which have a comparable area as the previously mentioned circular.

To solve the invention u. a. to pattern the x-ray generating layer, such as tungsten layer, in particular to coat on the substrate only one or more spatially limited, for example, circular limited areas with the x-ray generating layer. Advantageously, several delimited areas of the same or different diameter or surface area can be applied side by side, for example on a circle, in order to selectively produce differently sized or multiple focal spots. For this purpose, it is necessary to align the electron beam on the respective area or the respective areas. For this purpose, the invention provides either to divert the electron beam accordingly or to align the target with the regions at least vertically but possibly also in the direction of the electron beam (for the focusing thereof) by displacing it. As a result, the size of the focal spot is determined only by the structuring, ie the size of the areas that have been coated on the substrate, and a coarse focusing of the electron beam is only necessary to use a large proportion of the electron beam for the generation of X-rays.

The direction of the electron beam is the mean direction of the emitted electron beams. The entirety of the emitted electron beams is regarded as the electron beam.

The deflection of the electron beam is limited with the means available in known X-ray tubes possible, the displacement of the Targets is not intended because the vacuum chamber is tightly closed by the target.

Another object of the invention, therefore, is to enable displacement of the target while still maintaining the vacuum of the x-ray tube.

To solve the invention u. a. in that the vacuum chamber of the X-ray tube is closed by a separate exit window, which allows at least a portion of the electron beam to pass, for example in the form of a thinner substrate, and the target is arranged outside the vacuum chamber of the X-ray tube and displaceable therewith. The target is placed directly on the outside of the exit window and still contains the appropriately designed substrate to absorb remaining electron beams and dissipate the resulting heat. Since the exit window is made with a thinner substrate to allow sufficient electron beams through, the required vacuum of about 10e-6 mbar to the environment may not be directly achievable. The invention therefore also provides that the vacuum of the X-ray tube is limited to a pre-vacuum of about 10e-3 mbar through the exit window, wherein the pre-vacuum is delimited to the environment by the target. Since the target now only has to delineate the lower prevacuum to the environment in comparison to X-ray tubes according to the prior art, it is possible to make the target displaceable by corresponding displaceable sealing devices or membranes at least perpendicular to the direction of the electron beam. By using membranes, a shift in the direction of the electron beam may also be provided.

The invention provides for the solution of a device for generating X-radiation (X-ray tube) u. a. before, at least consisting of an electron beam source, a deflection device for deflecting and focusing the electron beam onto a target, and a target, the target consisting of a substrate layer, for example a diamond layer, and a layer, such as a tungsten layer, which is applied thereto when irradiated with electron beams and X-radiation; which is characterized in that the X-ray generating layer is structured, wherein the structuring has a limited range or a plurality of separate limited areas (focal spots), particularly preferably circular limited area or areas whose diameter or <5 microns, preferably < 1 micron, more preferably <0.5 microns, wherein the optionally present multiple areas have or may have different diameters or areas, and wherein the electron beam and the target perpendicular to the propagation direction of the electron beam are mutually adjustable to direct the electron beam to the area or at least one of the areas.

In particular, the invention is characterized in that the means for deflecting the electron beam are designed to align the electron beam on one of the X-ray emitting areas (focal spots).

Preferably, it is provided that the device comprises means for displacement of the target at least perpendicular to the propagation direction of the electron beam, preferably additionally comprises means for displacement in the direction of the electron beam.

In particular, the invention is characterized in that the device has a vacuum chamber, in which the means for generating and focusing the electron beam are arranged, wherein the vacuum chamber has an at least partially transparent exit fender for electrons and with respect to the outer side of the exit window, the target with X-rays is arranged generating region or areas, wherein the device comprises means for displacement of the target, which has an adjustment perpendicular to the direction of the electron beam and preferably in the direction of the electron beam.

Preferably, the invention provides that the exit window is formed by a second target without X-ray generating layer or regions, wherein the substrate of the second target has a smaller thickness than the substrate of the actual target, in particular a thickness <100 .mu.m, more preferably one Thickness of <50 microns has.

It should also be emphasized that exit window and target are arranged such that the exit window closes the vacuum chamber in such a way that between exit window and target a pre-vacuum with higher pressure, for example about 10e-2 mbar to 10e-4 mbar, as the vacuum in the vacuum chamber , For example, about 10e-6 mbar, is present, wherein the pre-vacuum is completed to the outside through the target, wherein the conclusion by the target is designed to be displaceable at least perpendicular to the X-ray direction.

To solve the invention also provides a method for generating X-ray radiation by means of an X-ray tube described above, which is characterized in that for generating an X-ray generating area (focal spot), in particular particularly small or variable focal spot, particularly preferably circular focal spot diameter <5 microns, preferably <1 .mu.m, more preferably <0.5 microns, electron beam and target at least perpendicular to the direction of the electron beam, preferably additionally in the direction of the electron beam, are shifted from each other, so that the electron beam impinges on the structured region or alternatively on one of the structured regions or on a plurality of the structured regions, preferably by displacing the target, wherein the target is particularly preferably arranged displaceably outside a vacuum chamber sealed by an exit window.

The subject matter of an independent invention is a method for compressing volume data such as voxel data (voxel volume) of computed tomography. In particular, the method finds application in the storage and further processing of volume data to be used for the dimensional or geometric evaluation of surface data of workpieces. The method is also intended for applications in which individual areas inside the workpiece must be available for evaluation.

Conventional compression techniques for volume data, such as the voxel data that results from computed tomography or other volume-generating techniques, are based on compressing the entire volume with a uniform compression method and thus quality. This is necessary in order to be able to carry out evaluations later in the entire volume, such as, for example, finding and evaluating such as classifying or determining the volume, inclusions, bubbles, voids, fibers or the like in the sense of a material inspection or, for example, finding and evaluating of organs, vessels or other features in medical applications.

Known methods are, for example, what are known as wavelet methods or methods which use delta coding, as described, for example, in US Pat DE102005007530B4 mentioned. In the delta coding, the deviation of the gray values between adjacent voxels is used for the storage, whereby regions of identical or almost identical gray values with high compression can be stored. Corresponding methods are known for 2D data (pictures) as jpg or jpeg coding or for picture sequences (movies) as mpg or mpeg coding.

All lossless compression methods typically do not achieve very high or sufficiently high compression rates, which keeps the amount of data quite large. Lossy compressions would lead to a limitation of the accuracy in the later determination of the surfaces or in the proposed dimensional or geometry measurements, which may not be desirable.

A further object of the present invention is therefore to compress volume data with a particularly high compression rate, without restricting the accuracy for the determination of dimensional or geometric data, in particular surface data.

To solve the invention u. a. in a first step, segmenting the volume data into internal volume data, external volume data, and volume data near the surface, and preferably volume data near in-lying features. In a second step, the inner volume data, the outer volume data and the volume data near the surface, and preferably also the volume data near in-house features, are separately compressed, the inner and outer data being compressed more strongly and in particular more lossy compressed than the volume data near the surface, and preferably also the volume data near in-lying features. The volume data near the surface, and preferably also the volume data near inline features, are not compressed or less lossy compressed.

• – innenliegende Volumendaten,
• – außenliegende Volumendaten,
• – Volumendaten nahe der Oberfläche des Körper
• – und vorzugsweise Volumendaten nahe innerliegender Merkmale wie Lunker, Einschlüsse, Blasen, Fasern oder ähnlichem

und in einem zweiten Schritt die innenliegenden und/oder außenliegenden Volumendaten und die Volumendaten nahe der Oberfläche, und vorzugsweise auch die Volumendaten nahe innerliegender Merkmale, separat komprimiert werden, wobei die innenliegenden und/oder außenliegenden Volumendaten stärker, insbesondere stärker verlustbehaftet, komprimiert werden als die Volumendaten nahe der Oberfläche, und vorzugsweise auch als die Volumendaten nahe innerliegender Merkmale.To solve the invention also provides a method for compressing volume data of a body, in particular volume data such as voxel data (voxel volume), which were preferably determined in a computed tomography that is characterized in that the volume data are segmented in a first step in

• - internal volume data,
• - external volume data,
• - Volume data near the surface of the body
• And preferably volume data near underlying features such as voids, inclusions, bubbles, fibers or the like

and in a second step, compressing the inner and / or outer volume data and the volume data near the surface, and preferably also the volume data near inner features separately, compressing the inner and / or outer volume data more strongly, in particular more lossy, than that Volume data near the surface, and preferably also as the volume data near internal features.

This ensures that the inside of the body, such as workpiece, present internal volume data are very strong and thus compactly compressed. The quality of the compressed internal data is significantly reduced. However, this does not disturb because they are not needed for the later evaluation of features on the surface or near-internal features. The volume data required for this purpose at the surface or near the surface and optionally the volume data near internal features are stored without loss or only slightly compressed, whereby the accuracy is maintained. Volume data near the surface indicates the volume data in which significant gray scale differences previously set are present between the workpiece interior and the environment of the workpiece. The gray values of the workpiece interior and the environment are usually the maximum and minimum gray values and are taken, for example, from a histogram of all gray values. Corresponding methods for surface extraction, which can also be used for segmentation, are also referred to as ISO threshold methods. The average (50%) threshold (ISO 50 threshold) between the workpiece interior and the environment is used to find the surface. Extended methods for surface determination use search lines through the previously inaccurately determined at least in their position surface of the workpiece. Both methods are exemplary in the EP1861822B1 which is fully incorporated herein by reference. An extended method using modified voxel data based on the search line method described above is disclosed in U.S.P. DE102013109632.8 described. Volume data near intrinsic features are detected by material differences and the associated gray scale gradient in the voxel volume. For multi-material workpieces, reference is also made to the methods described above.

In particular, the invention is characterized in that the volume data near the surface, and preferably also the volume data near in-lying features, are not compressed or compressed less lossy than the inner and / or outer volume data.

Preferably, it is provided that the body is a workpiece and the compressed volume data for dimensional or geometric evaluation of features that are defined by the surface or parts of the surface of the workpiece and / or present in the interior of the workpiece material interfaces are used.

Features on the surface are, for example, planes or curved surfaces such as cylinder sections, spherical sections, etc., from which dimensions such as distances, diameters, lengths or angles are determined. Internal features are for example inclusions, bubbles, voids, etc., for example, the volume or simply the presence is determined, or fibers whose orientation, ie direction is determined, for example.

In particular, the invention is characterized in that the compression takes place by means of delta compression and / or jpg or jpeg method and / or mpg or mpeg method or similar method, wherein the inner and / or outer volume data with lower quality, In particular, formation of larger classes of related voxel gray values are compressed than the volume data near the surface.

The class formation means that voxels of similar gray values are stored under a gray value. The larger or wider a class is, the more gray values that are adjacent in terms of size are combined to a gray value, and the greater is the space saving. Classes of width 10, for example, combine all the gray values from 1 to 10 to the gray value 5, all the gray values from 11 to 20 to the gray value 15 and so on. By contrast, a class width of 5 means that in each case all gray values from 1 to 5 for gray value 3, all gray values from 6 to 10 for gray value 8 etc. are combined, which leads to a higher quality but lower compression.

Preferably, the invention provides that the known methods of surface extraction using an ISO threshold and / or several search lines by a previously inaccurate at least in their position specific surface and / or the modification of the voxel data are used for segmentation.

In the known methods for determining contour points from volume data of a computer tomography surface points are determined at the transition of the material to be examined, in particular to be measured workpiece to the surrounding air by the gray value perpendicular to a coarse, so in their position still inaccurate, determined surface along Search lines, in particular at inflection points is examined, as for example in the EP1861822A1 is described. The coarsely determined surface is determined by means of the so-called ISO fast-value method, in which a gray value roughly characterizing the transition between material and air is determined, and the coarsely determined surface is determined at the points at which the gray values of the voxels of the volume data meet this threshold value exhibit. The resolution for the location of Surface points can also be in the sub-voxel range. The disadvantage, however, is that present in the interior of the workpiece material transitions, such as material transitions between two different materials or material transitions to enclosed gases such as air, can not be determined in the rule. Internal contours can also be, for example, fibers which have a spatial extent, as present for example in fiber composite materials.

Another object of the present invention is therefore also to detect material transitions inside volume data produced by computer tomography, and in particular to track detected material transitions in order to detect closed contours or free-form surfaces of the material transitions inside the volume data and to determine and supply corresponding contour points link.

To solve the invention u. a. that the volume data are searched in layers and the material transitions are detected in each layer, in which the gray value gradients in the layers are determined on gray value change, in particular turning points of the gray value curve or maximum points of the gray value changes along arbitrary search lines or by other contour finding algorithms and in the layer or be tracked and linked across layers.

The invention provides for the solution u. a. a method for determining material transitions, in particular contour points at material transitions in volume data, which were determined by means of computed tomography, wherein the volume data voxel information (voxel data) in a three-dimensional voxel volume, wherein the individual voxels include the local material properties, in particular X-ray absorption, preferably in Form of gray values, which is characterized in that the voxel volume is examined in layers in one or more predetermined directions, wherein in each layer material transitions are detected and at the material transitions contour points are defined, within the layer or cross-layer adjacent contour points are assigned to each other ,

In particular, the invention is characterized in that adjacent contour points are connected to a contour, in particular three-dimensional free-form surfaces, for example in STL format, are formed.

It is preferably provided that contours are tracked within and / or across layers in order to determine contiguous contours or contour surfaces.

In the known method, a mask, preferably in addition to the measurement object, is introduced into the beam path of the radiation received from an x-ray detector of an x-ray source and imaged together with the workpiece on the x-ray detector in order to determine at least one of the focal spot size of an x-ray source Radiographic image to determine the sharpness of the features of the mask, such as the DE102006032607A1 describes. This results in the disadvantage that the mask either interferes with the imaging of the measurement object or adversely affects, in particular restricts, the measurement range available for the measurement object and thus the magnification of the measurement object on the x-ray detector. If the mask is to be measured without the measurement object, the measurement object must be laboriously manually removed from the beam path, whereby an automatic sequence, in particular the repeated determination and possibly adjustment of the focal spot is not possible.

Another object of the present invention is therefore to optimize the determination and adjustment of the focal spot size of an X-ray source so that the best possible measurement parameters, in particular maximum magnification and interference-free measurement, are available for the measurement of the workpiece and yet an automated measurement of the workpiece and Determination and, if necessary, adjustment of the focal spot size is made possible.

To solve the invention provides, inter alia, that on the one hand the driving in and out of the mask is provided in the beam path, and on the other hand, the driving in and out of the workpiece is provided in the beam path, wherein the workpiece during the time in which the image of the mask is recorded on the X-ray detector with this, is automatically removed from the beam path. This is particularly favorable to implement that the workpiece is already arranged on the turntable required for the measurement, but this can be moved out of the beam path. For this purpose, the use of movement axes is provided, as present for example as measuring axes in coordinate measuring machines. Also for the movement of the mask automation is preferably provided. Since the mask has to be arranged as close as possible to the focal point in order to realize the determination of the focal spot size with high accuracy, it is provided to use the filter changer, which is already arranged at this point, for exchanging beam filters for filtering the measuring radiation. This can be actuated automatically by the measuring program, whereby an automated process for the Moving in and out of the measuring object and the mask is realized in the beam path.

The invention provides for the solution u. a. a method for determining the size of the focal spot of an X-ray source, and / or for adjusting the size of the focal spot, by focusing the X-ray source forming the X-ray emitting target when hitting a target, wherein a mask comprising one or more features is disposed between the X-ray source and X-ray detector, preferably planar X-ray detector, is temporarily arranged by moving, and at least one transmission image is recorded with the X-ray detector, wherein the geometrical features are evaluated in the transmission image, in particular with respect to their image sharpness or contrast, and from the evaluation on the The size of the focal spot is inferred and / or the focusing of the electron beam of the X-ray source is adjusted, which is characterized in that the workpiece to be measured, which on a turntable between X-ray source or X-ray detector a is located, while the recording of the image of the mask on the X-ray detector, out of the beam path, that is detected by the X-ray detector portion of the radiation of the X-ray source is moved out, and wherein the mask is moved out during the measurement of the workpiece from the beam path.

In particular, the invention is characterized in that the mask is moved into and out of the beam path by means of an automatic filter changer, wherein the filter changer preferably has one or more beam filters which can be optionally introduced into the beam path at least during the measurement of the workpiece the filter changer preferably arranges the beam filter to be introduced or the mask to be introduced directly in front of the focal spot of the x-ray source, in particular in front of the exit window of the x-ray source, preferably at a distance of less than 10 mm, preferably less than 5 mm, particularly preferably less than 1 mm, in particular automatically arranges.

Preferably, it is provided that the determination and / or focusing of the focal spot takes place automatically, preferably after a predetermined time and / or operating time of the X-ray source.

In particular, the invention is characterized in that for the movement of the workpiece, in particular workpiece receiving turntable together with the workpiece, in the beam path and out of the beam path measuring axes, in particular the measuring axes of the coordinate measuring machine are used, in which the computed tomography sensor consisting of X-ray source, X-ray detector and turntable, preferably integrated.

In the known methods for operating a computer tomograph, the main components X-ray source, X-ray detector and turntable are present only once. In case of failure of a component is therefore likely to be a long time delay when one of the components must be replaced, especially because the new component has to be set up and calibrated consuming for operation. The calibration includes, for example, the arrangement at the intended position for the measurement and also includes the angular position or tilt, wherein the angular position adjusted or determined and later the results are corrected accordingly. This has the disadvantage that, in particular during continuous use of the computed tomography device due to the maintenance delay, high downtimes occur, which can result in economic damage.

A further object of the present invention is that a computer tomography device is set up such that in the event of failure of one of the components, in particular particularly preferred in the event of failure of the X-ray source, but also in the event of failure of the X-ray detector, possibly even in the event of failure of the turntable Computed tomography device with the least possible effort and loss of time can continue to operate.

To solve the invention u. a. in that at least one redundant X-ray source is provided in the device, which can be moved to the position provided for the measurement by means of a movement axis when the first X-ray source fails. This is particularly accurate by means of accurately positionable measuring axis or measuring axes, as they are present for example in a coordinate measuring machine. The replacement can be done manually by the operator or automatically. An exchange can also be provided without the presence of a failure, for example to save one of the components, for example to cool or the like, or to use a non-identical component, for example, X-ray tube with different beam spectrum or power or detector other size or number of pixels To realize, for example, other measurement tasks such as workpieces of different sizes or transmittance or required measurement resolution. Alternatively, it is also intended to exchange the X-ray detector or the turntable or to provide several of the components X-ray source, X-ray detector and turntable exchangeable in any combination.

The invention provides, inter alia, a method for the examination, in particular dimensional measurement, of at least one workpiece with a computed tomography device, comprising at least a first x-ray tube, a first x-ray detector, a first turntable for receiving and rotating the workpiece to be examined (first components) and at least one movement axis, preferably measuring axis, particularly preferably measuring axis of a coordinate measuring machine, in which the computed tomography device is integrated, characterized in that the computed tomography device further comprises a second, preferably identical to the first x-ray tube, x-ray tube and / or a second, preferably identical to the first X-ray detector, X-ray detector and / or a second, preferably identical to the first turntable, turntable (second components), wherein if necessary, in particular failure of the respective first component, respectively second component in each case one of the axes of motion is displaced manually, particularly preferably automatically, to the position of the respectively first component, by preferably starting in each case first and second component from a respective common axis of movement.

In particular, the invention is characterized in that respectively associated first and second components are operatively calibrated or set up for operation in the computed tomography device and in case of failure of the respective first component respectively associated second component means of the respective axis of motion to the position of each first component is moved and the second component is used for the examination or measurement.

Preferably, it is provided that in each case associated first and second components are operatively metered or set up for operation in the computed tomography device and are used by the operator either selectively or by an automatic, preferably alternately, for operation by the respective component to be used is moved to the respective original position of the respective first component by means of the respective movement axis.

To solve the invention also provides a computer tomography device comprising at least a first x-ray tube, a first x-ray detector, a first turntable for receiving and rotating the workpiece to be examined (first components) and at least one axis of movement, preferably measuring axis, particularly preferably measuring axis of a coordinate measuring machine, in which is the computer tomography device is integrated, before, which is characterized in that the computed tomography device further comprises a second, preferably identical to the first X-ray tube, X-ray tube and / or a second, preferably identical to the first X-ray detector, X-ray detector and / or a second , Preferably identical to the first turntable, turntable has (second components), wherein each second component is displaceable by one of the axes of movement to the position of the respective first component, preferably by first and second component of each one he emanating common axis of motion, preferably in case of failure of the respective first component manually, particularly preferably automatically, each second component to the position of the respective first component is displaceable.

The features previously described in combination may also form in other combinations or on their own a teaching according to the invention. In that regard, the disclosure is not to be interpreted as limiting.

Further details, advantages and features of the invention will become apparent not only from the claims, the features to be taken from them - alone and / or in combination - but also from the following description of the figures.

Show it:

1 1 is a schematic representation of a device according to the invention in a first embodiment and parts of the method according to the invention,

2 a schematic diagram of a device according to the invention in a second embodiment and parts of the inventive method,

3 a schematic diagram of a device according to the invention in a third embodiment and parts of the inventive method,

4 a first schematic representation of a device according to the invention for computer tomography with optical components between scintillator and optical detector,

5 a second schematic representation of a device according to the invention for computer tomography with optical components between scintillator and optical detector,

6 Sectional view of a voxel volume of a workpiece made of two materials (drawn in with X-ray computed tomography) existing interfaces between the materials and the individual materials and the surrounding medium, as well as the assignment of the threshold values S _{_AB} , S _{_AC} , S _{_BC} to the interfaces),

7 Representation of the sectional view of the 6 surface _descriptions found (A: surface _descriptions found with the threshold S _{_AB} ; B: surface _descriptions found with the threshold S _{_AC} and C: surface _descriptions found with the threshold S _{_BC} ),

8th Presentation of the merging of the selected or summarized surface descriptions 7 to an overall geometric description of the workpiece,

9 a schematic diagram of an X-ray tube with transmission target according to the prior art,

10 1 is a schematic diagram of a device according to the invention of an X-ray tube with a transmission target,

11 a schematic diagram of an inventive device of an X-ray tube with transmission target in a second embodiment with a separate exit window and external target,

12 3 shows a schematic diagram of an apparatus according to the invention of an X-ray tube with a transmission target in a third embodiment with a separate exit window and external target, and a pre-vacuum.

13 a schematic representation of volume data to be compressed and

14 a schematic representation of the compressed volume data.

1 shows a schematic diagram of a device according to the invention in a first embodiment, comprising a computed tomography sensor, which in turn an X-ray source 101 , an x-ray detector 102 and a mechanical axis of rotation (turntable) 103 includes, and an intermediate piece 106 , which exemplifies a drift body 108 in the form of a drift ball, a workpiece holder 111 and a workpiece 109 , A turntable 103 consists at least of the non-rotatable part 105 and one to this about the axis of rotation 103b along the arrow 103a rotatable turntable 104 , where the turntable 104 an exchange interface 110 having. A counterpart to this interface 110 is at an intermediate piece 106 attached so that the intermediate piece 106 and according to this example together with the workpiece holder 111 and the workpiece 109 at the interface 110 and thus on the turntable 104 can be coupled. After this first embodiment are workpiece 109 and drift ball 108 at the same time in the X-ray detector 102 captured area of the X-ray source 101 emitted radiation (measuring radiation) 101 and the illustration of the workpiece takes place 109a and the drift ball 108b , From the shift 108c the picture of the drift ball 108b to the position of the drift ball at an earlier time, for example, recorded directly after the calibration of the computed tomography sensor, results in the drift correction to be made. However, the earlier point in time can also be an earlier assumed rotational position from the several rotational positions to be taken for the tomography of the workpiece 109 be. This corrects drift during tomography. This is necessary, for example, in the case of long-term measurements, that is, if, for example, a large number of rotational positions have to be assumed or if long exposure times are present.

In the 2a and 2 B the device according to the invention is the 1 shown in a second slightly modified embodiment. The workpiece 109 is closer to the x-ray source for greater magnification 101 arranged. workpiece 109 and drift sphere or calibration body 108 can no longer simultaneously on an x-ray detector 102 be imaged. The same would result, for example, if a larger workpiece is to be measured with the same magnification. To take turns the workpiece 109 to measure by computer tomography, as in the 2a represented, and at any time a drift ball or a calibration on the X-ray detector 102 in one or more rotational positions of the axis of rotation 103 and optionally a calibration body 108 , in particular test ball, to be measured by computer tomography, as in 2 B shown, is the axis of rotation 103 , and so is the intermediate piece 106 , the workpiece holder 111 and the workpiece 109 , in the direction of the axis of rotation ( 103b ), ie in the direction of the arrow 112 adjustable.

In the 3a and 3b the device according to the invention is the 2 shown in a further slightly modified embodiment. It is envisaged that either a correspondingly shaped workpiece holder 111 at the interface 110 is arranged, as is the 3a shows, or an intermediate piece 106 like this 3b shows. This embodiment is preferably used when between a calibration 108 , in particular test ball or calibration ball, and a workpiece 109 to be changed back and forth. Not shown are a magazine and an automatic Changing device, for example, for an automatic change between workpiece holder 111 and intermediate piece 106 can be used.

4 shows a first schematic diagram of a device according to the invention for computed tomography with optical components 311 and 309 between scintillator 304 and optical detector 310 , The measurement object 303 is between the X-rays 302 emitting X-ray source 301 and the scintillator 304 and on the around the rotation axis 306 rotatable part of a mechanical axis of rotation 305 arranged. When radiating with the measuring radiation 302 created in the scintillator 304 the optical radiation 307 at the side of the scintillator facing away from the target 304 distributed over the entire surface and distributed over a large angular range (Lambert radiator), for example, by the partial beams 307a . 307b and 307c indicated. As a low-cost optical component, the largest possible part of the optical radiation 307 detected, according to the invention is a Fresnel lens 311 provided that is known to produce optical aberrations. The Fresnel lens 311 forms the optical radiation 307 towards the optical detector like CCD or CMOS camera 310 with at least partial focusing takes place. In addition, another optical component, such as a lens or zoom optics 309 be provided. This leads to a further focus on the optical detector 310 and preferably can also be designed such that the aberrations of the Fresnel lens 311 at least partially corrected, so be compensated. According to the invention is also provided, the aberrations at the with the optical detector 310 take pictures taken. Corresponding methods are known from image processing or microscopy and include the calibration of a known, for. B. calibrated, measuring object. When measuring the location-dependent deviations occurring in the image are determined to the known target image of the known measurement object and then used in the actual measurement for location-dependent correction of the recorded images of the actual workpiece.

The to 4 alternative device the 5 comprises alternatively to the Fresnel lens 311 a mirror, for example, section of a parabolic mirror 308 , for detecting and deflecting the optical radiation 307 on the optical detector 310 , Function and reference numbers otherwise correspond to those of 4 ,

The optical components 308 . 3011 . 309 and the optical sensor 310 can also be designed individually to one another or jointly movable, without this being shown. In this case, the optical components are designed correspondingly smaller, since in each case only a part of the optical radiation 307 recorded and on the optical detector 310 must be steered and images in several differing relative positions to the scintillator 304 recorded and put together to form an overall picture. In this respect is on the in the DE102013108367A1 referred to devices and methods described.

Based on 6 By way of example, the presence of three different materials A, B and C, wherein, for example, material C is the ambient air is shown. For the gray values or mean gray values assigned to the materials in the voxel volume, the gray value 200 is defined for the material A, the gray value 100 for the material B and the gray value 10 for the material C, for example. In the transition areas between the materials, ie in the region of the material boundaries shown in the figure with thin lines, the non - ideal X - ray tomographic imaging and the associated "washout" of the edge transitions also result in other gray values, in particular gray value transitions between the individual materials Gray values of the materials forming the boundary.

In 7a are the surface _descriptions determined between the material _boundaries , which result when using a first threshold value _{S_AB} , the first threshold value being determined as the threshold value associated with the material _transition between the material A and the material B, this threshold value _{S_AB being} exemplary 155 is. Accordingly, between the materials A and B, the material boundary or the point cloud to be assigned to the material boundary results 401 , Gray values, which likewise correspond to the threshold value of 155, however, also occur at the material transition between the materials A and C, so that the points offset from the sought material boundary between the materials A and C also exist 402 be determined first.

In the 7b will that respect 7a described method, but now with the second threshold corresponding to the transition between the material A and C, wherein the second threshold S _{_AC is} exemplified 105. This results in the points 403 , and in addition the point cloud 404 , which is shifted to the desired material transition between the materials A and B.

In the 7c For example, the process is repeated for the threshold S _{_BC} = 55 that exists between materials B and C. This results in the point cloud 405 at the material transition between the materials B and C and a more points cloud shifted to the desired material transition between the materials A and C, with the reference numeral 406 ,

The previously designated as shifted points clouds 402 . 404 and 406 must be excluded from the further evaluation according to the invention, since this is point clouds that are shifted to the material transitions and these are not assigned. In the 8th are the remaining surface descriptions off 7a . 7b and 7c shown assembled to a total geometric description of the workpiece.

9 shows a schematic diagram of an X-ray tube 500 According to the state of the art. In a vacuum chamber 501 is in a vacuum 502 an electron-generating cathode 503 and the anode 504 , creating an electron beam 509 is generated in the direction of the target 506 is directed. The target 506 closes the vacuum 502 the X-ray tube 500 towards the outside and has the substrate 507 , z. Diamond, and the x-ray generating layer 508 , z. As tungsten, on. At the end of the x-ray tube 500 but can also have separate exit windows 510 be provided, wherein the substrate is then inside the x-ray tube 500 located. By means of the deflection device or deflection means 505 becomes the electron beam 509 bundled and distracted and thereby on a specific point of the shift 508 focused, which forms the focal point. The deflection means 505 generate an electric field and consist for example of capacitors, in the simplest case of plate capacitors. Several capacitors or capacitor pairs are conceivable. Other means of generating electric fields, such as coils, are also used. By focusing by means of the deflection 505 the area becomes on the layer 508 defined by the electron beam 509 is taken and forms the focal spot. The target 506 is heated by the irradiation with electrons and therefore has a good heat-conducting substrate 507 on, which is mostly cooled. Corresponding cooling devices are not shown for reasons of simplicity. By irradiation of the layer 508 with the electron beam 509 gives the irradiated area (focal spot) the X-rays 514 from. The construction shown is a so-called transmission target 506 because of the incidence of the electron beam 509 opposite side of the target 506 emitted X-radiation 514 is used.

However, the invention is not limited to transmission targets. Likewise, the application of the teaching of the invention is also provided for so-called reflection targets. In these the electron beam hits 509 at a predefined angle of about 30 to 60 degrees to the layer 508 and the X-rays 514 is on the same side of the layer 508 , also delivered at a predefined angle.

10 shows a schematic diagram of an inventive device of an X-ray tube 500 where the target 506 no continuous layer 508 has more, but only one or more structured areas, of which, by way of example, the areas 508-1 . 508-2 and 508-3 are shown, which optionally by the respective aligned electron beam 509-1 . 509-2 respectively. 509-3 to be hit. The regions preferably have a circular boundary and the size of the focal spot can be set exactly by the choice of the diameter of the respective region, even to very small values below 5 μm, 1 μm or even 0.5 μm, without the electron beam 509 must be exactly focused. The areas 508 For example, they may be arranged on a circle. Other shapes such as rectangles or grids are also conceivable. Next to the area 508-1 Falling electron beam shares do not contribute to the generation of X-rays 514 at. In the variant shown here, the alignment of the electron beam takes place 509 on the area 508-1 represented as the electron beam 509-1 , ie the adjustment of the electron beam 509 perpendicular to the propagation direction of the electron beam 509 to the target 506 , and possibly also in the direction of the electron beam 509 , by means of the deflection means 505 , The adjustment of the electron beam 509 perpendicular to the direction of electron beam direction through the deflection means 505 is only possible to a limited extent, so the areas 508-1 . 508-2 and 508-3 etc. must be close to each other or preferably only one area 508-1 is present or used.

11 shows a schematic diagram of an inventive device of an X-ray tube 500 with separate exit window 510 and one outside the vacuum chamber 501 lying structured coated target 506 with the area 508-1 or more areas, of which the areas 508-1 . 508-2 and 508-3 are shown by way of example. In the variant shown here, the alignment of the electron beam takes place 509 on the area 508-1 represented as the electron beam 509-1 , ie the adjustment of the electron beam 509 perpendicular to the propagation direction of the electron beam 509 to the target 506 , and possibly also in the direction of the electron beam 509 , Advantageously by means of outside the vacuum chamber 501 arranged deflection means 511 by shifting or adjusting the target 506 in the two directions perpendicular to the direction of the electron beam 509 and optionally by means of outside the vacuum chamber 501 arranged deflection means 512 by shifting or Adjustment of the target 506 in directions of the electron beam 509 , The adjustment of the electron beam 509 perpendicular to the direction of electron beam direction through the deflection means 511 is possible in much larger, almost arbitrary dimensions, so that the multiple areas 508-1 . 508-2 . 508-3 etc. may also be far apart or preferably not just one area 508-1 is present or used, but several areas 508-1 . 508-2 . 508-3 etc. may optionally be used to produce different sized focal spots for different measurement tasks. The areas 508-1 . 508-2 . 508-3 etc., but can also be the same size, and used sequentially or alternately to minimize the wear of the target or to increase the life. Any mixture of equal and different sized areas 508 are also provided. The exit window 510 is designed to be as large as possible of the electron beam 509 pass. For this purpose, for example, it is made of a different material than the substrate 507 or as a thinner substrate. The mechanical stability of the exit window 510 However, it must be big enough for the vacuum 502 complete.

12 shows a schematic diagram of an inventive device of an X-ray tube 500 with separate exit window 510 and one outside the modified vacuum chamber 501 lying structured coated target 506 where the target 506 from a membrane 513 emanates. Between the target 506 and the modified exit window 510a is a fore-vacuum 502a intended. The target 506 closes the pre-vacuum 502a towards the outside and the exit window 510a closes the pre-vacuum 502a inside to the vacuum 502 from. This has the advantage that the exit window 510a mechanically less stable, ie thinner than the exit window 510 according to the in 11 illustrated variant, can be performed, reducing the proportion of the exit window 510a passing radiation of the electron beam 509 is increased. Due to the flexible membrane 513 can be the target 506 as previously described by the deflection means 511 respectively. 511 and 512 be moved.

13 shows a schematic diagram of volume data to be compressed 600 , for simplicity in a 2D representation. For example, the 2D representation may be a section through the entire volume 600 (Voxel volume or voxel data). The following explanations apply mutatis mutandis to three-dimensional data (volume data). The voxel volume 600 consists of individual voxels (volume elements), which are represented in the figure by a corresponding grid, and each of which is assigned a gray value. By way of example, the figure shows voxels with a first gray value or gray scale range, which surrounds the workpiece (usually air), and thus the external volume data or voxels 601 represent. These are shown without hatching and bear the reference numeral 601 , The internal volume data or voxels 604 represent the workpiece interior and have a second gray scale or gray scale area and are shown hatched thick. The volume data or voxels near the surface 603 of the body and workpiece have a third gray value, here in particular gray scale range due to the material transition, and are shown hatched in a hatched manner.

In the 14 are the volume data 600 from the previous figure shown in compressed form. The larger grid in the interior areas 604 and outlying areas 601 is intended to illustrate that here a higher compression level was applied by storing adjacent voxels of approximately equal gray values, with the allowable gray scale differences compared to the ranges 602 near the surface 603 of the workpiece are significantly larger, the quality, in particular the resolution decreases.

In the real case lie in the individual areas 601 . 602 and 604 not exactly constant gray values. Inside the workpiece 604 and in the environment, however, the gray scale differences are usually much smaller than in the area 602 near the surface. A particularly high compression in the areas 601 and 604 results from the formation of broad classes, ie large permissible gray-scale differences in the assignment to the classes. In the area 602 If there is no compression, the raw data are stored, or very narrow classes are formed, both to obtain the quality, in particular the resolution in the gray scale range and thus the structure resolution.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

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• DE 102005007530 B4 [0135]
• EP 18618221 B [0140]
• DE 102013109632 [0140]
• EP 1861822 A1 [0147]
• DE 102006032607 A1 [0153]

Claims (16)

Device for computer tomographic measurement of a workpiece ( 109 ), at least comprising a computed tomography sensor system comprising an X-ray source ( 101 ), an area-wide X-ray detector ( 102 ) and a mechanical axis of rotation (turntable) ( 103 ) with one about a rotation axis ( 103b ) rotatable part (turntable) ( 104 ), and at least one workpiece holder ( 111 ), from the turntable ( 104 ) directly or indirectly and means for fixing the workpiece ( 109 ), wherein the device is designed to transmit radiographic images of the workpiece ( 109 ) in several rotational positions about the axis of rotation ( 103b ) and the workpiece ( 109 ) to reconstruct a volume data set (voxel volume) and preferably surface points from the volume data set for the dimensional measurement of the workpiece ( 109 ), characterized in that the turntable ( 104 ) an exchange interface ( 110 ), on the manually or automatically interchangeable optionally the workpiece holder ( 111 ) or an intermediate piece ( 106 ) containing one or more calibration bodies ( 108 ) and / or one or more drift bodies ( 108 ), can be coupled. Method for drift correction for a computer tomography measurement, in particular using the arrangement according to claim 1, wherein a workpiece to be measured is arranged between an X-ray emitting X-ray source and an X-ray receiving X-ray detector in a workpiece holder and transmissive images in several rotational positions (measuring rotational positions) of the workpiece, whereby relative movements (drift) occurring between the X-ray source, in particular the X-ray emitting focal spot of the X-ray source, and the X-ray detector and / or the workpiece with respect to a calibration state occur before the actual measurement and / or occurring during the actual measurement be corrected by the position of a drift body is detected in one or more radiographic images, wherein the workpiece detecting radiographic images or portions of this radiographic Reconstructs images to a volume data set (voxel volume) and preferably surface points from the volume data set for dimensional measurement of the workpiece to be extracted, characterized in that a drift body is detected, which is contained in an intermediate piece, wherein before the computed tomography measurement, the intermediate piece, the drift body in recorded in one or more selected rotational positions and the adapter is replaced again, and / or either - before the computed tomography measurement an adapter connected to the workpiece holder adapter is changed, which remains switched during the computed tomography measurement, or - during the computed tomography measurement in selected rotational positions Replaced before the measurement substitute workpiece holder and temporarily replaced the intermediate piece and then the workpiece age is replaced again. A method for checking the specification, in particular probing deviation on a test ball, a computer tomography sensor preferably with the device according to claim 1, wherein as calibrated body a calibrated test ball is used, which is arranged between an X-ray emitting X-ray source and an X-ray receiving X-ray detector and of the Transmitted radiographs in several rotational positions (measurement rotational positions) of the Prüfkugel are recorded, the radiographic images to a volume data set (voxel volume) reconstructed and surface points from the volume data set for dimensional measurement of the test ball, in particular the diameter and the shape of the test ball, extracted, characterized that the test ball is arranged in an intermediate piece, which is exchanged via an exchange interface, wherein preferably the Intermediate piece is connected to the workpiece holder and for computer tomographic measurement of the workpiece, the test ball is moved out by positioning the turntable in a direction along the axis of rotation from the area detected by the X-ray detector radiation emitted by the X-ray source (measuring radiation). A method for measuring, in particular the geometry of the position of the components of the computed tomography sensors to each other and / or the magnification, a computed tomography sensor preferably with the device according to claim 1, wherein a calibration ball, in particular uncalibrated calibration ball is used as the calibration body between an X-ray emitting X-ray source and an X-ray receiving X-ray detector is arranged and are recorded by the transmission images in a plurality of rotational positions and / or a plurality of translational relative positions to the unit of X-ray source and X-ray detector, wherein in each of the radiographic images determines the position and / or diameter of the calibration ball is, characterized in that the Einmesskugel is arranged in an intermediate piece, which is exchanged via an exchange interface, wherein preferably the intermediate piece with the Werkstückha For the computertomographic measurement of the workpiece, the test ball is moved out of the area of the radiation emitted by the X-ray source (measuring radiation) by positioning the turntable in one direction along the axis of rotation. Method for correcting temperature effects on dimensional measurements on a test object with a computer tomograph, preferably X-ray computer tomographs, particularly preferably in a coordinate measuring machine integrated CT, at least one radiation source, preferably X-ray tube, a mechanical axis of rotation for rotation of a measured object, and a detector, preferably X-ray detector , wherein the measurement object is irradiated in several rotational positions of the radiation of the radiation source and respectively associated 2D radiographic images are taken, from which by means of reconstruction three-dimensional volume information in voxel format (so-called voxel volume) are calculated, in this voxel volume data (voxel data, for example in shape gray values) for local beam absorption, and where surface dots are generated from the voxel data, preferably in the region of material transitions are characterized in that the size (voxel size or voxel edge length), preferably size and position (voxel position), of the voxel volume voxel is corrected as a function of the particular temperature and the coefficient of linear expansion associated with the respective voxel to produce a corrected voxel volume, wherein this correction of the voxel sizes, and preferably the voxel positions, is alternatively implemented by adjusting the voxel data of the voxel and the adjacent voxels. Device for recording a plurality of radiographic images of a measured object ( 303 ) for performing a computed tomography, wherein radiographic images in a plurality of rotational positions, adjustable by a rotating device such as mechanical axis of rotation ( 305 ), in which the measuring object ( 303 ) and a computed tomography sensor ( 301 . 304 . 308 . 309 . 310 . 311 ) are arranged rotated relative to each other, preferably the measuring object ( 303 ), are receivable, wherein the computed tomography sensor at least consists of a radiation source such as x-ray tube ( 301 ), at least one areal scintillator ( 304 ) and at least one planar optical detector ( 310 ), wherein the transmission images of at least one optical detector ( 310 ) and are reconstructable into a voxel volume from which preferably surface points can be determined at material transitions, wherein the light emitted by the scintillator ( 304 ) emitted optical radiation ( 307 ) at least partially from the at least one optical detector ( 310 ), and wherein the computer tomography sensor is preferably integrated in a coordinate measuring machine, wherein preferably means for adjusting the size and / or position of the optical detector ( 310 ), the optical radiation ( 307 ) donating first area and / or other areas of the scintillator ( 304 ), preferably means by which the optical detector ( 310 ) and the scintillator ( 304 ) are displaceable relative to each other, characterized in that between the scintillator ( 304 ) and the optical detector ( 310 ) one or more optical components ( 308 . 309 . 311 ) arranged by the scintillator ( 304 ) emitted optical radiation ( 307 ) on the optical detector ( 310 ), wherein at least one of the optical components ( 308 . 309 . 311 ) is optimized to maximize light output relative to that of the scintillator ( 304 ) emitted optical radiation ( 307 ), this or these optical components ( 308 . 309 . 311 ) in particular have or may have aberrations. Computed tomography method for dimensional measurements on a measurement object with a device according to at least claim 6, characterized in that the image errors occurring due to the properties of the optical components used are at least partially corrected, preferably by at least one distortion correction and / or distortion correction and / or light correction. Dark correction is performed. Computed tomography method for dimensional measurements on a measurement object with a computed tomography sensor system, comprising at least one radiation source such as X-ray source and a radiation detector, wherein the measurement object is rotatably arranged on a mechanical axis of rotation between the X-ray source and the radiation detector and wherein received and combined radiographic images in different rotational positions of the workpiece be reconstructed in particular, wherein - X-ray source and / or radiation detector relative to the measurement object, and preferably the mechanical axis of rotation, wherein the measurement object is fixedly disposed on the mechanical axis of rotation, are positionable, and wherein the rotation of the workpiece by means of a combination of rotational and translational relative movement between Workpiece and detector takes place about a different axis of rotation from the physical axis of rotation, and / or - only a limited perpendicular to the axis of rotation of the object to be measured detected in all rotational positions by the detector, characterized in that in that a line detector or a line of a flat detector or a plurality of adjacent lines of a flat detector is used as a radiation detector, but in a restricted number with respect to all lines, preferably a maximum of one quarter, more preferably one hundredth of all lines or preferably not more than ten Lines, wherein preferably a helical tomography is performed or wherein the detector or the detector area used are piecewise offset in the direction of the axis of rotation to receive two-dimensional radiographic images. Method for measuring workpieces consisting of at least two different materials with X-ray computed tomography, wherein volume elements (voxels) having voxel volume is generated by the local X-ray absorption (local attenuation coefficients), preferably in the form of gray values, associated with the voxels, characterized in that the material boundaries between the materials and / or between the materials and the surrounding medium, such as air, are determined and from this the geometric description of the surfaces, in particular point cloud of existing of the respective materials components of the workpiece are determined completely or partially. Apparatus for generating X-ray radiation (X-ray tube), at least consisting of an electron beam source, a deflection device for deflecting and focusing the electron beam onto a target, and a target, wherein the target consists of a substrate layer, for example a diamond layer, and one applied thereto, when irradiated with electron beams X-ray generating layer such as tungsten layer is, characterized in that the X-ray generating layer is structured, wherein the structuring of a limited area or a plurality of separate limited areas (focal spots) has, more preferably circular limited area or areas whose diameter < 5 microns, preferably <1 .mu.m, more preferably <0.5 .mu.m, wherein the optionally present multiple regions have or may have different diameters or areas, and wherein the electron trahl and the target are perpendicular to the propagation direction of the electron beam to each other adjustable to direct the electron beam to the area or at least one of the areas. Method using at least the device mentioned in the preceding claim 10, characterized in that for generating an X-ray generating area (focal spot), in particular a particularly small or variable focal spot, particularly preferably circular focal spot diameter <5 microns, preferably <1 micron, especially preferably <0.5 μm, electron beam and target are displaced relative to each other at least perpendicular to the direction of the electron beam, preferably additionally in the direction of the electron beam, so that the electron beam impinges on the structured region or alternatively on one of the structured regions or several of the structured regions, preferably by the target is displaced, wherein particularly preferably the target is arranged displaceably outside a closed by an exit window vacuum chamber. Method for compressing volume data of a body, in particular volume data such as voxel data (voxel volume), which were preferably determined in a computed tomography, characterized in that the volume data are segmented in a first step in - in-volume data, - external volume data, - volume data near the surface the body - and preferably volume data near in-lying features such as voids, inclusions, bubbles, fibers or the like and in a second step the inner and / or outer volume data and the volume data near the surface, and preferably also the volume data near in-lying features, are compressed separately in that the inner and / or outer volume data are compressed more strongly, in particular more heavily lossy, than the volume data near the surface, and preferably also as the volume data near inlying features. Method for determining material transitions, in particular contour points at material transitions in volume data, which were determined with the aid of computer tomography, the volume data having voxel information (voxel data) in a three-dimensional voxel volume, wherein the individual voxels contain the local material properties, in particular x-ray absorption, preferably in shape of grayscale values, characterized in that the voxel volume is examined in layers in one or more predetermined directions, wherein material transitions are detected in each layer and contour points are defined at the material transitions, wherein adjacent contour points are assigned to one another within the layer or across layers. Method for determining the size of the focal spot of an X-ray source, and / or for adjusting the size of the focal spot, by means of Focusing the electron beam of the X-ray source which forms the X-ray emitting focal point when striking a target on a target, whereby a mask having one or more features is interposed between the X-ray source and the X-ray detector, preferably planar X-ray detector, by moving it, and at least one X-ray image is taken with the X-ray detector , wherein the geometrical features are evaluated in the radiographic image, in particular with regard to their image sharpness or contrast, and from the evaluation to the size of the focal spot is concluded and / or the focusing of the electron beam of the X-ray source is set, characterized in that the measuring workpiece, which is arranged on a turntable between the X-ray source or X-ray detector, during the recording of the image of the mask on the X-ray detector, from the beam path, that is detected by the X-ray detector Berei the radiation of the X-ray source, is moved out, and wherein the mask is moved out during the measurement of the workpiece from the beam path. Method for examining, in particular dimensionally measuring, at least one workpiece with a computer tomography device, comprising at least a first x-ray tube, a first x-ray detector, a first turntable for receiving and rotating the workpiece to be examined (first components) and at least one movement axis, preferably measuring axis, particularly preferred measuring axis of a coordinate measuring machine, in which the computed tomography device is integrated, characterized in that the computed tomography device further comprises a second, preferably identical to the first x-ray tube, x-ray tube and / or a second, preferably identical to the first x-ray detector, x-ray detector and / or a second, preferably identical to the first turntable, turntable comprises (second components), wherein if necessary, in particular failure of the respective first component, each second component by one of the axes of motion manually, especially rs preferably automatically, is moved to the position of the respective first component, preferably by each emanating first and second component, each of a common axis of movement. Computed tomography device comprising at least a first x-ray tube, a first x-ray detector, a first turntable for receiving and rotating the workpiece to be examined (first components) and at least one axis of movement, preferably measuring axis, particularly preferably measuring axis of a coordinate measuring machine, in which the computed tomography device is integrated , characterized in that the computed tomography device further comprises a second, preferably identical to the first X-ray tube, X-ray tube and / or a second, preferably identical to the first X-ray detector, X-ray detector and / or a second, preferably identical to the first turntable, turntable (second Components), wherein each second component is displaceable by a respective one of the axes of movement to the position of the respective first component, preferably by each first and second component emanate from a respective common axis of movement, preferably in case of failure of the respective first component manually, more preferably automatically, each second component is displaceable to the position of the respective first component.

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