JP6654893B2 - Confocal displacement meter - Google Patents

Description

  The present invention relates to a confocal displacement meter using light in a wide wavelength band.

  2. Description of the Related Art A confocal displacement meter is known as a device for measuring a displacement of a surface of a measurement object by a non-contact method. For example, Patent Literature 1 describes a chromatic point sensor (CPS) system that measures a distance from a predetermined reference position to a measurement target as a displacement of a surface of the measurement target. The CPS of Patent Document 1 has two confocal optical paths. Light of a plurality of wavelengths is input to each optical path, and light that has passed through any one of the optical paths is selectively output to a measurement target.

  The first optical path is configured such that light of different wavelengths is focused at different distances near the surface position of the measurement object in the optical axis direction. Light that has passed through the first optical path is reflected on the surface of the measurement target. Of the reflected light, only light focused at the position of the opening disposed on the first path as a spatial filter passes through the opening and is guided to the wavelength detector. The spectrum profile (first output spectrum profile) of the light detected by the wavelength detector includes a component indicating the measurement distance (distance-dependent profile component) and also includes a distance-independent profile component.

  The second optical path is configured such that lights of different wavelengths are focused at substantially the same distance near the surface position of the measurement target. Light that has passed through the second optical path is reflected on the surface of the measurement target. Of the reflected light, only light focused at the position of the opening disposed in the second path as a spatial filter passes through the opening and is guided to the wavelength detector. The spectrum profile (second output spectrum profile) of the light detected by the wavelength detector does not include a distance-dependent profile component, but includes only a distance-independent profile component. The second output spectral profile is used to correct the first output spectral profile for potential measurement errors associated with distance-independent profile components.

JP 2013-130581 A

  In the CPS system described in Patent Literature 1, reliability is improved by performing the above-described correction on the first output spectrum profile. Specifically, measurement errors due to the material component of the measurement target, the spectral profile component of the light source associated with the light source, or the component associated with the wavelength detector are reduced as the distance-independent profile components. However, in the confocal displacement meter, a measurement error having a degree larger than the surface roughness occurs due to the influence of irregular reflection on the surface of the measurement object. In the CPS system of Patent Document 1, such a measurement error cannot be reduced.

  An object of the present invention is to provide a confocal displacement meter capable of reducing a measurement error.

(1) A confocal displacement meter according to the present invention is a confocal displacement meter that measures a displacement of an object to be measured using a confocal optical system, and includes a light projecting unit that emits light having a plurality of wavelengths. An optical axis of light emitted from the light projecting unit , which is provided on a first optical path of the light , and irradiating the object to be measured by sequentially shifting the optical axis of the light emitted by the light projecting unit ; A light irradiating section that sequentially shifts in a direction perpendicular to the direction of irradiation and sequentially irradiates a plurality of continuous or intermittent portions of the measurement object, and a light irradiation section that irradiates the measurement object with light along the optical axis direction. A first optical member that generates chromatic aberration and converges light having chromatic aberration, and a first pinhole that sequentially passes light of a wavelength reflected while being focused on a plurality of portions of the measurement object. a first pinhole member, sequentially passes through the first pinhole And a displacement measuring unit for calculating a displacement of the measurement object based on the signal strength of each wavelength of the average signal corresponding to the average of the intensity of each wavelength for a plurality of light corresponding to the number of parts.

In this confocal displacement meter, light having a plurality of wavelengths is emitted by the light projecting unit. The optical axis of the light emitted by the light projecting unit is sequentially shifted by the light irradiating unit provided on the first optical path of the light, so that the light irradiated on the measurement target is aligned with the optical axis of the light. It is sequentially shifted in the orthogonal direction, and is sequentially irradiated on a plurality of continuous or intermittent portions of the measurement object. Chromatic aberration along the optical axis direction is generated by the first optical member in the light irradiated to the measurement target by the light irradiation unit. Light having chromatic aberration is converged by the first optical member. Light of a wavelength reflected while being focused on a plurality of portions of the measurement object sequentially passes through the first pinholes of the first pinhole member. The displacement of the measurement object is determined by the displacement measuring unit based on the signal intensity for each wavelength of the average signal corresponding to the average of the intensity for each wavelength of the plurality of lights corresponding to the plurality of portions sequentially passing through the first pinhole. Is calculated.

Due to irregular reflection on the surface of the measurement object, light focused at a position different from the position of the surface of the measurement object may pass through the first pinhole. Even in such a case, according to the above configuration, intensities of the plurality of lights corresponding to the plurality of portions that have passed through the first pinholes in the average signal for each wavelength are averaged. This cancels out light components that cause random measurement errors due to diffuse reflection. As a result, it is possible to reduce an error in displacement of the measurement object measured by the confocal displacement meter.

(2) The displacement measuring unit is configured to sequentially disperse a plurality of lights corresponding to a plurality of portions sequentially passing through the first pinhole, and a plurality of lights corresponding to the plurality of portions sequentially separated by the dispersing unit. And a light receiving unit that outputs an electric light receiving signal indicating an amount of received light for each wavelength as an average signal with respect to the received light, and calculates a displacement of the measurement target based on the average signal. And a calculating unit.

In this case, a plurality of lights corresponding to a plurality of portions sequentially passing through the first pinhole are received by the light receiving section within a single exposure period. Therefore, the electrical light receiving signal indicating the amount of light received for each wavelength output from the light receiving unit is an average signal in which the intensities of the plurality of lights corresponding to the plurality of portions for each wavelength are integrated. According to this configuration, there is no need to perform an operation for generating an average signal. Thus, the displacement of the measurement target can be calculated efficiently.

(3) The displacement measuring unit sequentially splits the plurality of lights sequentially passing through the first pinhole, and sequentially receives the plurality of lights sequentially split by the splitting unit, and the plurality of lights sequentially received. A light receiving unit that outputs an electric light receiving signal indicating the amount of light received for each wavelength, and an average signal as a signal intensity for each wavelength by averaging or integrating a plurality of light receiving signals output from the light receiving unit for each wavelength. And a calculator for calculating the displacement of the measurement target based on the average signal.

  In this case, a plurality of light receiving signals respectively corresponding to a plurality of lights sequentially passing through the first pinhole are output by the light receiving unit. The average signal is calculated by averaging or integrating a plurality of light receiving signals output from the light receiving unit for each wavelength by the calculating unit. According to this configuration, in the calculation of the average signal, a desired average or integration can be performed in consideration of the intensities of a plurality of lights. Thereby, the displacement of the measurement object can be calculated more accurately.

(4) The displacement measuring unit sequentially splits a plurality of lights corresponding to a plurality of portions sequentially passing through the first pinhole, and a plurality of lights corresponding to the plurality of portions sequentially split by the splitting unit. the received within a plurality of exposure periods, and a light receiving section for outputting an electrical light reception signal indicating the received light amount for each wavelength for light received at a plurality of exposure periods, corresponding to a plurality of exposure periods output from the light receiving portion And calculating a mean signal as a signal intensity for each wavelength by averaging or integrating a plurality of received light signals for each wavelength, and calculating a displacement of the measurement object based on the mean signal.

In this case, a plurality of light beams corresponding to a plurality of portions sequentially passing through the first pinhole are received by the light receiving unit within a plurality of exposure periods, so that a plurality of light reception signals corresponding to the plurality of exposure periods are output. Is done. An average signal is calculated by averaging or integrating a plurality of light receiving signals corresponding to a plurality of exposure periods output from the light receiving unit for each wavelength by the calculating unit. According to this configuration, in calculating the average signal, desired averaging or integration can be performed in consideration of the intensities of a plurality of lights corresponding to a plurality of portions . Thereby, the displacement of the measurement object can be calculated more accurately.

  (5) The light irradiating unit sets the optical axis of the light emitted by the light projecting unit on the surface of the measurement target so that the light irradiates a plurality of portions on the annular region on the surface of the measurement target. It may be shifted along. According to this configuration, the burden on the physically operating portion of the light irradiation section is smaller than when a plurality of portions on the linear region on the surface of the measurement target are irradiated with light. Thereby, the life of the light irradiation part can be prolonged.

  (6) The outer diameter of the annular region may be 100 μm or more. In this case, light is reflected at a plurality of portions of a sufficiently large area on the surface of the measurement object. Therefore, in the average signal, a light component that generates a random measurement error due to diffuse reflection is sufficiently canceled. Thereby, the error of the displacement of the measurement object measured by the confocal displacement meter can be further reduced.

  (7) The outer diameter of the annular region may be 500 μm or less. In this case, the light irradiated to the measurement target by the light irradiation unit does not spread excessively large, and thus can pass near the center of the first optical member. Therefore, almost no aberration such as coma which lowers the measurement accuracy occurs. Thus, the displacement of the measurement target can be measured with higher accuracy.

  (8) The light irradiating section is formed of a member having a light transmitting property, includes a first light transmitting section having first and second surfaces, and a driving section, and includes a driving section. At least one of the first and second surfaces is disposed on the first optical path in a state of being inclined with respect to a plane orthogonal to the first optical path of the light emitted by the light projecting unit, and the driving unit includes: The first and second surfaces of the first light transmitting portion may be configured to rotate in a plane intersecting the first optical path.

  In this case, the optical axis of the light applied to the surface of the measurement object shifts from the optical axis of the light applied to the surface of the measurement object when the first light transmitting unit is not disposed. Therefore, by rotating the first light transmitting unit by the driving unit, it is possible to irradiate a plurality of portions on the annular region on the surface of the measurement target with a simple configuration.

  (9) The confocal displacement meter further includes a processing device and a first head unit, and the processing device includes a light projecting unit and a displacement measuring unit, and a first device that houses the light projecting unit and the displacement measuring unit. And the first head unit may include a light irradiation unit and a first optical member, and may further include a second housing that houses the light irradiation unit and the first optical member.

  In this case, a processing device including the light projecting unit and the displacement measuring unit and a head unit including the light irradiating unit and the first optical member are separately provided. Therefore, it is easy to use the first head member including the first optical member that generates appropriate chromatic aberration or the first optical member having an appropriate focal length according to the shape or arrangement of the measurement target. . Thereby, the displacement of the measurement object can be more easily measured.

  (10) The processing apparatus further includes a power supply unit housed in the first housing, and the power supply unit is connected to the light irradiation unit so that power can be supplied to the driving unit of the first head unit. Good. In this case, it is not necessary to house a device for supplying power to the drive unit in the second housing. Thereby, the first head portion can be reduced in size and weight.

  (11) The confocal displacement meter further includes a second head section and a second pinhole member having a second pinhole, and the second head section controls the light emitted by the light projecting section. A second optical member that generates chromatic aberration along the optical axis direction, converges light having chromatic aberration, and irradiates the object to be measured, and a third member and a fourth member that are formed of a light-transmitting member. A second light-transmitting part having a second light-transmitting part, and a third housing that houses the second optical member and the second light-transmitting part, and the third and fourth surfaces of the second light-transmitting part At least one of the surfaces is disposed on the second optical path in a state of being inclined with respect to a surface orthogonal to the second optical path of the light emitted by the light projecting unit, and the second pinhole is provided on the second optical path. Passes light of wavelength reflected while being focused on the surface of the measurement object by the second optical member of the head unit The displacement measurement unit calculates the displacement of the measurement target based on the signal intensity of the light passing through the second pinhole for each wavelength, and outputs the light emitted by the light projection unit to the first head unit. And the second head unit may be selectively guided.

  In this case, in the measurement using the second head unit, it is not necessary to irradiate a plurality of portions of the measurement target with light. Therefore, when the shape of the surface of the object to be measured is sufficiently smooth and the degree of irregular reflection is small, the object to be measured can be measured with sufficiently high accuracy and in a short time by using the second head unit. Can be.

  In the second head section, a second light transmitting section similar to the first light transmitting section in the first head section is arranged on the second optical path. According to this configuration, the length of the second optical path in the second head unit can be easily matched with the length of the first optical path in the first head unit. Therefore, it is easy to independently configure the confocal optical system using the first head unit and the confocal optical system using the second head unit.

  (12) The confocal displacement meter further includes an optical fiber. The optical fiber guides the light emitted by the light projecting unit to the first optical member, and is reflected by a plurality of portions of the measurement target. A plurality of lights sequentially passing through the first pinhole may be provided to the displacement measurement unit. In this case, the degree of freedom in the configuration of an optical path for guiding the light emitted by the light projecting unit to the first optical member and guiding the plurality of lights passing through the first pinhole to the light splitting unit is improved.

  (13) The end of the optical fiber may be a first pinhole. In this case, there is no need to separately arrange the first pinhole. Thereby, the configuration of the confocal displacement meter can be made compact.

  (14) The light projecting unit includes a light source that emits light of a single wavelength and a phosphor that absorbs light emitted by the light source and emits light of a wavelength different from the wavelength of light emitted by the light source. May be included. In this case, light having a plurality of wavelengths can be easily generated.

  According to the present invention, a measurement error of a measurement target can be reduced.

FIG. 1 is a schematic diagram illustrating a configuration of a confocal displacement meter according to an embodiment of the present invention. It is an example of a display of a value of a measurement result in a display. 6 is a display example of a light receiving signal waveform on a display device. FIG. 9 is a diagram for explaining the operation principle of a confocal displacement meter using a second measurement head. FIG. 4 is a diagram for explaining the operation principle of a confocal displacement meter using a first measurement head. FIG. 4 is a diagram illustrating an optical path of light when a driving unit rotates. It is a figure showing the field of the measurement object irradiated with light. FIG. 5 is a diagram illustrating a relationship between a wavelength of light received by a light receiving unit and an intensity of a light receiving signal. It is the top view and sectional drawing which show the structure of a light projection part. It is a schematic diagram which shows an example of the light reflected by a part different from a measurement object. FIG. 6 is a diagram illustrating a light reception waveform including an unnecessary component. It is a figure showing the base waveform of a light-receiving waveform. FIG. 7 is a diagram showing a received light waveform from which a base waveform has been removed. FIG. 4 is a diagram illustrating a path of light guided to a light receiving unit. FIG. 15 is a diagram illustrating a light reception waveform of light guided to the light receiving unit in FIG. 14. FIG. 9 is a partial longitudinal sectional view showing a first modification of the driving unit. FIG. 9 is a partial longitudinal sectional view illustrating a second modification of the driving unit. It is a figure showing the 1st-the 4th modification of a lens unit. It is a figure which shows the modification of a light projection part. It is a figure showing the modification of a spectrum part. FIG. 9 is a schematic diagram illustrating a configuration of a confocal displacement meter according to another embodiment.

(1) Basic Configuration of Confocal Displacement Meter Hereinafter, a confocal displacement meter according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing a configuration of a confocal displacement meter according to one embodiment of the present invention. As shown in FIG. 1, the confocal displacement meter 500 includes a processing device 100, a plurality of (two in this example) measurement heads 200, a light guide unit 300, and a control device 400. The light guide unit 300 includes a plurality of optical fibers, and optically connects the processing apparatus 100 and any one of the measurement heads 200. Hereinafter, when distinguishing the two measurement heads 200, one measurement head 200 is called a first measurement head 200A, and the other measurement head 200 is called a second measurement head 200B.

  The processing device 100 includes a housing 110, a light projecting unit 120, a spectral unit 130, a light receiving unit 140, an arithmetic processing unit 150, a power supply unit 160, and a display unit 170. The housing 110 houses the light emitting unit 120, the light splitting unit 130, the light receiving unit 140, the arithmetic processing unit 150, and the power supply unit 160. The light projecting unit 120 is configured to emit light in a wide wavelength band (for example, 500 nm to 700 nm), that is, light having a plurality of wavelengths. The detailed configuration of the light projecting unit 120 will be described later. The light emitted by the light projecting unit 120 is input to an optical fiber 311 of the light guide unit 300 described later.

  The light splitting unit 130 includes a diffraction grating 131 and a plurality of (two in this example) lenses 132 and 133. As described later, a part of the light emitted by the light projecting unit 120 and reflected on the surface of the measurement target S is output from the optical fiber 312 of the light guide unit 300. The light output from the optical fiber 312 is substantially collimated by passing through the lens 132, and is incident on the diffraction grating 131. In the present embodiment, the diffraction grating 131 is a reflection type diffraction grating. The light incident on the diffraction grating 131 is split so as to be reflected at different angles for each wavelength, and is focused on a one-dimensional position different for each wavelength by passing through the lens 133.

  The light receiving unit 140 includes an image sensor (one-dimensional line sensor) in which a plurality of pixels are arranged one-dimensionally. The imaging device may be a multi-segment PD (photodiode), a CCD (charge coupled device) camera or a CMOS (complementary metal oxide semiconductor) image sensor, or may be another device. The light receiving unit 140 is arranged such that a plurality of pixels of the image sensor receive light at a plurality of focusing positions different for each wavelength formed by the lens 133 of the spectral unit 130. Each pixel of the light receiving unit 140 outputs an analog electric signal (hereinafter, referred to as a light receiving signal) corresponding to the amount of received light.

  The arithmetic processing unit 150 includes a storage unit 151 and a control unit 152. The storage unit 151 includes, for example, a ROM (Read Only Memory), a RAM (Random Access Memory), or a hard disk. The storage unit 151 stores a displacement measurement program and various data used for displacement measurement. The control unit 152 includes, for example, a CPU (Central Processing Unit). The control unit 152 acquires a light receiving signal output by the light receiving unit 140 and executes a displacement measuring process of the measurement target S based on the displacement measuring program and data stored in the storage unit 151.

  The first measurement head 200A includes a housing 210 having a substantially axially symmetric shape (for example, a cylindrical shape), a lens unit 220, a flat plate member 230, and a driving unit 240. The housing 210 houses the lens unit 220, the flat plate member 230, and the driving unit 240. The flat plate member 230 is formed of a flat plate member having transparency. The flat member 230, for example, a flat glass, a lens element, or another element may be used.

  Power is supplied to the drive unit 240 from the power supply unit 160 of the processing apparatus 100 via a power cable (not shown). Therefore, it is not necessary to house a device for supplying power to the drive unit 240 in the housing 210. Thereby, the first measuring head 200A can be reduced in size and weight. The second measuring head 200B has the same configuration as the first measuring head 200A, except that the second measuring head 200B does not have the driving unit 240. The light irradiation unit 1 for shifting the optical axis of the light emitted from the first measurement head 200A is configured by the flat plate member 230 and the driving unit 240. Details of the light irradiation unit 1 will be described later.

  An optical fiber 314 of the light guide unit 300 described later is arranged in the housing 210. The light from the processing device 100 output from the optical fiber 314 passes through the flat plate member 230 and is guided to the lens unit 220. The lens unit 220 includes a refractive lens 221, a diffraction lens 222, and an objective lens 223. The light guided through the flat plate member 230 passes through the refraction lens 221 and the diffraction lens 222 in order. Thereby, chromatic aberration occurs in the light along the optical axis direction. Here, the optical axis means not only the optical axis when the optical axes of the refraction lens 221, the diffraction lens 222, and the objective lens 223 substantially coincide with each other, but also the refraction lens 221, the diffraction lens 222, and the It may mean any one or more optical axes of the objective lens 223. The objective lens 223 is arranged so that light having chromatic aberration can be focused at a position near the surface of the measurement target S.

  The light guide unit 300 includes a plurality (four in this example) of optical fibers 311 to 314, a fiber coupler 320, and a fiber connector 330. In the example of FIG. 1, the fiber coupler 320 is provided on the housing 110 of the processing device 100, and the fiber connector 330 is provided on the housing 210 of the measurement head 200. The present invention is not limited to this. The fiber coupler 320 may be provided in a portion other than the housing 110 of the processing device 100, and the fiber connector 330 may be provided in a portion other than the housing 210 of the measurement head 200. Good.

  The fiber coupler 320 has a so-called 1 × 2 configuration, and includes three ports 321 to 323 and a main body 324. The ports 321 and 322 and the port 323 are connected to the main body 324 so as to face each other with the main body 324 interposed therebetween. Light input to at least one of the ports 321 and 322 is output from the port 323. The light input to the port 323 is output from each of the ports 321 and 322.

  The fiber connector 330 includes two ports 331 and 332 and a main body 333. The port 331 and the port 332 are connected to the main body 333 so as to face each other with the main body 333 interposed therebetween. Light input to the port 331 is output from the port 332, and light input to the port 332 is output from the port 331.

  Optical fibers 311 and 312 are connected to ports 321 and 322 of the fiber coupler 320, respectively. An optical fiber 314 is connected to the port 332 of the fiber connector 330. The port 323 of the fiber coupler 320 and the port 331 of the fiber connector 330 are connected by an optical fiber 313.

  According to this configuration, the light emitted by the light projecting unit 120 of the processing device 100 is input to the port 321 of the fiber coupler 320 through the optical fiber 311. The light input to the port 321 is output from the port 323 and input to the port 331 of the fiber connector 330 through the optical fiber 313. The light input to the port 331 is output from the port 332 and is applied to the measurement target S through the optical fiber 314, the flat plate member 230, and the lens unit 220.

  Part of the light reflected on the surface of the measurement target S is input to the port 332 of the fiber connector 330 through the lens unit 220, the flat plate member 230, and the optical fiber 314. The light input to the port 332 is output from the port 331 and input to the port 323 of the fiber coupler 320 through the optical fiber 313. The light input to the port 323 is output from the ports 321 and 322. The light output from the port 322 is guided to the light splitting unit 130 through the optical fiber 312. Thereby, the displacement measurement processing is performed.

  The display unit 170 includes a display such as a 7-segment display or a dot matrix display. The display unit 170 is provided on the housing 110 of the processing device 100 and is connected to the arithmetic processing unit 150. On the display unit 170, numerical values such as a measured distance calculated by the displacement measurement processing of the arithmetic processing unit 150 are displayed.

  The control device 400 is configured by, for example, a personal computer, and is connected to the arithmetic processing unit 150 of the processing device 100. The control device 400 includes a display device 401, an operation unit 402, a CPU (Central Processing Unit) 403, and a memory 404. The display device 401 includes, for example, a liquid crystal display panel or an organic EL (electroluminescence) panel. The operation unit 402 includes a pointing device such as a mouse and a keyboard. The memory 404 stores a displacement measurement program and various data used for displacement measurement.

  The CPU 403 acquires the light receiving signal provided from the control unit 152, measures the displacement of the measurement target S based on the displacement measurement program and the data stored in the memory 404, and performs various processes related to the measurement result. . For example, the CPU 403 displays the value of the measurement result on the display device 401. Further, the CPU 403 displays the waveform of the light receiving signal provided from the control unit 152 on the display device 401. Further, the CPU 403 displays, on the display device 401, statistics on a plurality of measurement results obtained at a plurality of time points before the current time point.

  FIG. 2 is a display example of the value of the measurement result on the display device 401. FIG. 3 is a display example of the waveform of the light receiving signal on the display device 401. In the example of FIG. 2, a numerical value indicating the measurement result of the displacement is displayed on the display device 401 and a switch button 491 is displayed. In the example of FIG. 3, the display device 401 displays the waveform of the light reception signal acquired at the current time, and also displays the switch button 491. In the graph of FIG. 3 showing the waveform of the received light signal, the horizontal axis indicates the wavelength of the received light, and the vertical axis indicates the intensity of the received light signal.

  The user can switch the display state of the display device 401 to the display state of the received light waveform in FIG. 3 by operating the switching button 491 in FIG. 2 using the operation unit 402 in FIG. Further, the user operates the switching button 491 in FIG. 3 using the operation unit 402 in FIG. 1 to switch the display state of the display device 401 to the display state of the numerical measurement result values in FIG. it can.

  Further, the CPU 403 may set a reference range for determining whether or not the measurement target S is good or bad with respect to the measurement distance. In this case, when the measurement distance is within the reference range, a determination result (for example, “OK”) indicating that the measurement target S is a good product is displayed on the display device 401. On the other hand, when the measurement distance is out of the reference range, the determination result (for example, “NG”) indicating that the measurement target S is defective is displayed on the display device 401.

(2) Operation Principle of Confocal Displacement Meter FIG. 4 is a diagram for explaining the operation principle of the confocal displacement meter 500 using the second measurement head 200B. As shown in FIG. 4, the optical fiber 314 includes a core 310a and a clad 310b. The core 310a is covered with a cladding 310b. Light input to one end of the core 310a is output from the other end of the core 310a. The optical fibers 311 to 312 in FIG. 1 also have the same configuration as the optical fiber 314. The diameter of the core 310a is preferably 200 μm or less, more preferably 50 μm or less.

  The plate member 230 has two substantially parallel surfaces. One surface of the flat plate member 230 is called an entrance surface 231, and the other surface is called an exit surface 232. The flat plate member 230 is arranged in a state where the entrance surface 231 and the exit surface 232 are inclined with respect to a plane orthogonal to the optical axis of the optical fiber 314. In the second measuring head 200B, the length of the optical path in the second measuring head 200B is set to the length of the optical path in the first measuring head 200A by disposing the flat plate member 230 on the optical path of the light output from the optical fiber 314. Can be matched. Accordingly, the aberration can be minimized in the second measurement head 200B without the driving unit 240, similarly to the first measurement head 200A.

  The light output from the optical fiber 314 passes through the flat plate member 230 and then passes through the refraction lens 221 and the diffraction lens 222. This causes chromatic aberration in the light. The light in which chromatic aberration has occurred passes through the objective lens 223 and is focused at different positions for each wavelength. For example, light with a long wavelength is focused at a position near the objective lens 223, and light with a short wavelength is focused at a position far from the objective lens 223. The range between the focus position P1 closest to the objective lens 223 and the focus position P2 farthest from the objective lens 223 is the measurement range MR. In this example, the refractive lens 221 has a convex shape, and the diffractive lens 222 has a concave shape. In this case, chromatic aberration generated in light increases. Thereby, the measurement range MR can be enlarged.

  When the surface of the measurement target S exists in the measurement range MR, the light that has passed through the objective lens 223 irradiates the surface of the measurement target S, and is then reflected by the surface in a wide range. Here, in the present embodiment, the distal end portion of the optical fiber 314 functions as a spatial filter having minute pinholes. Therefore, most of the light reflected on the surface of the measurement target S is not input to the optical fiber 314.

  On the other hand, light having a specific wavelength focused at the position of the surface of the measurement target S is reflected by the surface, passes through the lens unit 220, and is input to the tip of the core 310a of the optical fiber 314. . The wavelength of the light input to the optical fiber 314 indicates the measurement distance. Here, the measurement distance is a distance from a predetermined reference position RP to a position on the surface of the measurement target S. In this example, the reference position RP is the position of the end of the housing 210 closest to the measurement target S.

  The light input to the optical fiber 314 is guided to the processing device 100 in FIG. 1, is separated by the diffraction grating 131, and is focused by the lens 133 at a different position for each wavelength. The plurality of pixels of the light receiving unit 140 are respectively arranged at in-focus positions of a plurality of light beams different for each wavelength. Therefore, each pixel of the light receiving unit 140 receives light having a wavelength corresponding to the pixel, and outputs a light receiving signal.

  According to this configuration, the wavelength of the received light can be specified by specifying the position of the pixel of the light receiving unit 140 that outputs the light receiving signal. Further, the measurement distance can be specified by specifying the wavelength of the received light. However, light that is focused at a position different from the position of the surface of the measurement target S may be input to the optical fiber 314 due to irregular reflection of light on the surface of the measurement target S. In this case, a measurement error having a degree greater than the surface roughness of the measurement target S occurs in the measurement distance specified by the processing device 100. Therefore, the second measuring head 200B is used for measuring the measuring object S having a small degree of irregular reflection (for example, the measuring object S having a smooth surface such as glass) with high accuracy and in a short time.

  On the other hand, when measuring the measurement target S having a rough surface, the first measurement head 200A is used. FIG. 5 is a diagram for explaining the operation principle of the confocal displacement meter 500 using the first measurement head 200A. As described above, the first measuring head 200A has the same configuration as the second measuring head 200B, except that the first measuring head 200A further includes the driving unit 240. The light irradiation unit 1 is configured by the flat plate member 230 and the driving unit 240. As shown in FIG. 5, the driving unit 240 is, for example, a hollow motor, and includes a cylindrical fixed unit 241 and a cylindrical rotating shaft 242. The rotation shaft 242 is provided in a hollow part of the fixed part 241 so as to be concentric with the fixed part 241.

  The end of the optical fiber 314 is fixed to a hollow portion of the rotating shaft 242, for example, while being inserted into a ferrule (not shown). The flat plate member 230 is attached to the rotating shaft 242 in a state where the entrance surface 231 and the exit surface 232 are inclined with respect to a plane orthogonal to the optical axis of the optical fiber 314. In the present embodiment, the rotating shaft 242 rotates in a state where light is emitted from the optical fiber 314. The rotation speed of the driving section 240 is preferably 100 rpm or more, and more preferably 6000 rpm or more. In the present embodiment, the driving section 240 continuously rotates, but the present invention is not limited to this. The drive unit 240 may rotate intermittently.

  FIG. 6 is a diagram illustrating an optical path of light when the drive unit 240 rotates. FIG. 6A shows an optical path of light at an initial time point. FIG. 6B shows an optical path of light at a time when a certain time has elapsed from the initial time (when the driving unit 240 has rotated 90 degrees from the initial time). FIG. 6C shows the optical path of the light at a point in time when a certain period of time has passed further from the point in time in FIG. 6B (at a point in time when the drive unit 240 has been further rotated by 90 degrees from the point in time in FIG.

  As shown in FIGS. 6A to 6C, the light output from the optical fiber 314 is incident on the incident surface 231 of the flat plate member 230 substantially in parallel with the optical axis of the optical fiber 314. Since the incident surface 231 of the flat member 230 is inclined with respect to the surface orthogonal to the optical axis of the optical fiber 314, the light incident on the incident surface 231 of the flat member 230 is inclined at an angle to the incident angle. The light passes through the flat plate member 230. Thereafter, the light is emitted from the emission surface 232 of the flat plate member 230 at an angle substantially equal to the incident angle. Thereby, it is possible to irradiate the measurement target S with light through the lens unit 220 of FIG. 1 while shifting the optical axis of the light.

  FIG. 7 is a diagram illustrating an area of the measurement target S to which light is irradiated. As shown in FIG. 7, in the present embodiment, light is applied to an annular region IR (hereinafter, referred to as an irradiation region IR) on the surface of the measurement target S. According to this configuration, the load on the physically operating portion of the light irradiation unit 1 is smaller than when light is irradiated on a linear region on the surface of the measurement target S. Thereby, the life of the light irradiation unit 1 can be prolonged. The outer diameter OD of the irradiation region IR can be determined by selecting the inclination angle, the thickness, the refractive index, and the like of the flat plate member 230. In this example, the outer diameter OD is, for example, 250 μm. As described above, since the outer diameter OD is very small, the user recognizes the irradiation region IR as a single point instead of an annular shape.

  Of the light reflected from the irradiation region IR of the measurement target S, light focused at the position of the irradiation region IR is input to the optical fiber 314 through the lens unit 220 and the flat plate member 230, and is received by the light receiving unit 140. Is done. FIG. 8 is a diagram illustrating a relationship between the wavelength of the light received by the light receiving unit 140 and the intensity of the light receiving signal. The horizontal axis in FIG. 8 indicates the wavelength of the received light, and the vertical axis indicates the intensity of the received light signal. The same applies to FIGS. 11 to 13 described later. The horizontal axis in FIG. 8 and FIGS. 11 to 13 described below correspond to the positions of the pixels of the light receiving unit 140.

  The light receiving unit 140 receives the light input to the optical fiber 314 at each point in time during which the driving unit 240 makes one rotation. In FIG. 8, the waveforms of light reception signals (hereinafter, referred to as light reception waveforms) W1 to W4 of light input to the optical fiber 314 at any four points are indicated by dotted lines and dashed lines in a virtually separated state. , Two-dot chain line and broken line, respectively. The peak wavelengths of the light receiving waveforms W1 to W4 (hereinafter, referred to as peak wavelengths) are λ1 to λ4, respectively. The peak wavelengths λ1 to λ4 of the plurality of light reception waveforms W1 to W4 are different from each other due to irregular reflection on the surface of the measurement target S.

  Therefore, when the first measurement head 200A is used, the light receiving unit 140 performs exposure during a period in which the driving unit 240 makes one rotation. In the present embodiment, light receiving section 140 continuously performs exposure, but the present invention is not limited to this. The light receiving section 140 may perform exposure intermittently.

  Each pixel of the light receiving section 140 outputs a light receiving signal integrated during the exposure period. Accordingly, the light receiving signal output from the light receiving unit 140 is subjected to intensity averaging processing. The averaging process means a process of generating an average signal corresponding to the average of the intensity for each wavelength of a plurality of lights reflected by a plurality of portions of the irradiation region IR of the measurement target S and sequentially passing through the pinhole. I do. In this example, the averaging process is an integrating process. In FIG. 8, the light receiving waveform W0 after the averaging process output by the light receiving unit 140 is indicated by a solid line. The peak wavelength of the light reception waveform W0 is λ0.

  As described above, by optically averaging the received light waveform W0, light components that generate random measurement errors due to irregular reflection are canceled. Therefore, the peak wavelength λ0 is closer to the peak wavelength corresponding to the true measurement distance than the peak wavelengths λ1 to λ4 at each time point. Here, the true measurement distance is a measurement distance to be specified when diffused reflection of light does not occur. Therefore, by specifying the peak wavelength λ0 of the received light waveform W0, the measurement distance can be specified more accurately.

  The outer diameter OD of the irradiation area IR is preferably 100 μm or more. In this case, light is reflected at a plurality of portions of a sufficiently large area on the surface of the measurement target S. Therefore, in the average signal, a light component that generates a random measurement error due to diffuse reflection is sufficiently canceled. Thereby, the error of the displacement of the measurement object S measured by the confocal displacement meter 500 can be further reduced.

  Further, the outer diameter OD of the irradiation region IR is preferably 500 μm or less. In this case, since the light irradiated on the measurement target S by the light irradiation unit 1 does not spread excessively large, it can pass near the center of the lens unit 220. Therefore, almost no aberration such as coma which lowers the measurement accuracy occurs. Thus, the displacement of the measurement target S can be measured with higher accuracy.

(3) Light Projecting Unit FIGS. 9A and 9B are a plan view and a cross-sectional view illustrating the configuration of the light projecting unit 120, respectively. As shown in FIG. 9, the light projecting unit 120 includes a light source 121, a phosphor 122, a ferrule 123, a lens 124, a holder 125, a filter element 126, and an element holder 127. The element holder 127 includes a light source fixing part 127A, a ferrule fixing part 127B, and a lens fixing part 127C. The light source 121, the ferrule 123, and the lens 124 are fixed to the light source fixing portion 127A, the ferrule fixing portion 127B, and the lens fixing portion 127C of the element holder 127, respectively.

  The light source 121 is a laser light source that emits light of a single wavelength. In the present embodiment, the light source 121 emits light in a blue region or an ultraviolet region having a wavelength of 450 nm or less. The phosphor 122 absorbs excitation light in a blue region or an ultraviolet region and emits fluorescence in a wavelength region different from the wavelength region of the excitation light. The phosphor 122 may emit fluorescent light in a yellow region, may emit fluorescent light in a green region, or may emit fluorescent light in a red region. Further, the phosphor 122 may be composed of a plurality of fluorescent members.

  The ferrule 123 holds the end of the optical fiber 311 of the light guide 300 of FIG. The lens 124 is disposed between the light source 121 and the ferrule 123. One end surface of an annular holder 125 is attached to an end of the ferrule 123 (optical fiber 311). The phosphor 122 is accommodated in the inner periphery of the holder 125. A filter element 126 is attached to the other end surface of the holder 125 so as to cover the phosphor 122 in the holder 125. The filter element 126 is a reflection filter that reflects light in a yellow region, a green region, or a red region and transmits light in a blue region or an ultraviolet region.

  According to this configuration, the light emitted by the light source 121 passes through the lens 124 and is condensed on the phosphor 122 as excitation light. The phosphor 122 absorbs the excitation light and emits fluorescence. Here, the excitation light transmitted without being absorbed by the phosphor 122 and the fluorescence from the phosphor 122 are mixed to generate light in a wide wavelength band. In the present example, the thickness of the phosphor 122 in the optical path direction is, for example, 10 μm to 200 μm in order to generate light in which excitation light and fluorescence are mixed at a desired ratio. Further, the concentration of the phosphor 122 in the holder 125 is formed, for example, to 30% to 60%.

  The light generated in the light projecting unit 120 is input to the optical fiber 311 by passing through the ferrule 123. The fluorescent light emitted by the phosphor 122 in the direction opposite to the optical fiber 311 is reflected by the filter element 126 in the direction of the optical fiber 311. Thus, the fluorescent light can be efficiently input to the optical fiber 311.

  In this example, the phosphor 122 is accommodated in the holder 125, but the present invention is not limited to this. The phosphor 122 may be applied to the end surface of the ferrule 123. In this case, the light projecting unit 120 does not include the holder 125. Further, the light projecting unit 120 includes the filter element 126, but the present invention is not limited to this. When sufficient fluorescent light is input to the optical fiber 311, the light projecting unit 120 may not include the filter element 126.

(4) Arithmetic Processing Unit The storage unit 151 of the arithmetic processing unit 150 in FIG. 1 stores in advance a conversion formula for the pixel position of the light receiving unit 140, the peak wavelength λ0 of the output light receiving waveform W0, and the measurement distance. Have been. The control unit 152 of the arithmetic processing unit 150 specifies the position of the pixel that outputs the light-receiving signal, and based on the specified position of the pixel and the conversion formula stored in the storage unit 151, determines the peak wavelength λ0 and the peak wavelength λ0 of the light-receiving waveform W0. The measurement distance is calculated sequentially. Thereby, the thickness, distance, or displacement of the measurement target S can be measured. In addition, the control unit 152 removes a base waveform and corrects a temperature characteristic of the light receiving unit 140, which will be described below, in order to more accurately calculate the measurement distance.

(A) Removal of Base Waveform Light reflected by a portion different from the measurement target S may be received by the light receiving unit 140. FIG. 10 is a schematic diagram illustrating an example of light reflected by a portion different from the measurement target S. In the example of FIG. 10, light (light indicated by an arrow) directly reflected by the refractive lens 221 of the lens unit 220 is input to the optical fiber 314. Such light includes an unnecessary component without including a component indicating the measurement distance.

  FIG. 11 is a diagram showing a received light waveform W0 including an unnecessary component. As shown in FIG. 11, the received light waveform W0 includes three peaks P0, Px, and Py. The peak P0 is generated by light reflected on the surface of the measurement target S. The peak P0 has a steep shape, and the peak wavelength is λ0. The peak Px is generated by light reflected by a portion different from the measurement target S. The peak Px has a smooth shape, and the peak wavelength is λx.

  The peak Py is generated by the light of the light source 121 (FIG. 9) having the oscillation wavelength λy reflected by a portion different from the measurement target S. The peak Py has a steep shape, and the peak wavelength is λy. In this example, since the intensity of the excitation light emitted from the light source 121, which is a laser light source, is large, light having a wavelength component corresponding to the excitation light is not used as measurement light.

  The peak wavelength λx is relatively close to the peak wavelength λ0, and the width of the peak Px is wide. Therefore, the peak P0 is buried in the peak Px. In this case, it is difficult to accurately specify the peak wavelength λ0. Therefore, a correction for removing a portion (hereinafter, referred to as a base waveform BL) caused by the peak Px from the received light waveform W0 is performed.

  FIG. 12 is a diagram showing a base waveform BL of the received light waveform W0. In the present embodiment, control unit 152 obtains base waveform BL in FIG. 12 by applying low-pass filter processing for identifying peak Px and peak P0 to received light waveform W0. The method of acquiring the base waveform BL is not limited to the above method, and data indicating the base waveform BL may be stored in the storage unit 151 of FIG. 1 in advance. In this case, the control unit 152 corrects the received light waveform W0 based on the acquired base waveform BL in FIG. 12 so as to remove the base waveform BL from the received light waveform W0 in FIG.

  FIG. 13 is a diagram showing the received light waveform W0 from which the base waveform BL has been removed. In the example of FIG. 13, the peak wavelength λ0 is slightly shifted to a shorter wavelength side than the peak wavelength λ0 of FIG. As described above, by removing the base waveform BL from the received light waveform W0, the peak wavelength λ0 can be specified more accurately. As a result, the measurement distance can be calculated more accurately. Note that the portion of the received light waveform W0 caused by the peak Py does not affect the accurate specification of the peak wavelength λ0, and is not removed from the received light waveform W0. The present invention is not limited to this, and a process for removing a portion caused by the peak Py from the received light waveform W0 may be performed.

(B) Correction of Temperature Characteristics of Light Receiving Unit As described above, light having a specific wavelength is received by a pixel of the light receiving unit 140 associated with the wavelength. However, due to a change in the position of the light receiving surface of the light receiving unit 140 or a change in the inclination of the light receiving surface of the light receiving unit 140 due to a change in ambient temperature, light having a specific wavelength may be received by a pixel different from the pixel associated with the light. . In this case, the measurement distance cannot be calculated accurately. Therefore, correction of the temperature characteristic of the light receiving unit 140 described below is performed.

  FIG. 14 is a diagram illustrating a path of light guided to the light receiving unit 140. As shown in FIG. 14, to the light receiving section 140, in addition to the primary light separated by the diffraction grating 131, the zero-order light regularly reflected by the diffraction grating 131 is guided. In FIG. 14, the first-order light is indicated by a solid line, and the zero-order light is indicated by a chain line. The zero-order light is not used for calculating the measurement distance.

  FIG. 15 is a diagram illustrating a light receiving waveform W0 of light guided to the light receiving unit 140 in FIG. The horizontal axis in FIG. 15 indicates the position of the pixel of the light receiving unit 140, and the vertical axis indicates the intensity of the light receiving signal. As shown in FIG. 15, the received light waveform W0 includes a portion corresponding to the primary light and a portion corresponding to the zero-order light. Similar to the received light waveform W0 in FIG. 11, the portion of the received light waveform W0 corresponding to the primary light includes three peaks P0, Px, and Py. The portion of the received light waveform W0 corresponding to the zero-order light includes one peak Pz.

  The position of the pixel where at least one of the peaks Px, Py, and Pz should appear in the storage unit 151 in FIG. 1 is stored in advance as a reference position. The control unit 152 specifies the positions of the peaks Px to Pz corresponding to the reference positions stored in the storage unit 151. The control unit 152 calculates the displacement of the pixel position by comparing the positions of the specified peaks Px to Pz with the reference position, and corrects the position of the light receiving waveform W0 based on the calculated displacement of the pixel position. In FIG. 15, the light-receiving waveform W0 after the position is corrected is indicated by a dotted line.

  In addition, in the storage unit 151, the interval between pixels at which the centers of at least two peaks of the peaks Px, Py, and Pz should appear is stored in advance as a reference interval. The control unit 152 specifies the intervals between the peaks Px to Pz corresponding to the reference intervals stored in the storage unit 151. The control unit 152 calculates the shift in the pixel interval by comparing the specified interval between the peaks Px to Pz with the reference interval, and corrects the shape of the light receiving waveform W0 based on the calculated shift in the pixel interval.

  As the correction of the temperature characteristic of the light receiving unit 140, only one of the correction of the position of the light receiving waveform W0 based on the shift of the pixel position and the correction of the shape of the light receiving waveform W0 based on the shift of the pixel interval may be performed. Both may be performed. The correction of the temperature characteristic of the light receiving unit 140 is performed before the removal of the base waveform BL. By specifying the peak P0 of the light reception waveform W0 after the correction has been performed, the measurement distance can be calculated more accurately.

(5) Effect In the confocal displacement meter 500 according to the present embodiment, light having a plurality of wavelengths is emitted by the light projecting unit 120. The light emitted by the light projecting unit 120 is sequentially irradiated on the irradiation region IR of the measurement target S by the light irradiation unit 1 in the first measurement head 200A. Chromatic aberration along the optical axis direction is generated by the lens unit 220 in the light irradiated on the measurement target S by the light irradiation unit 1. Light having chromatic aberration is converged by the lens unit 220. Light having a wavelength reflected while being focused at a plurality of portions of the irradiation region IR of the measurement target S sequentially passes through the optical fiber 314.

  The plurality of lights that have passed through the optical fiber 314 are sequentially guided to the light splitting unit 130 through the fiber connector 330, the optical fiber 313, the fiber coupler 320, and the optical fiber 312, and are split. The plurality of lights split by the light splitting unit 130 are received by the light receiving unit 140 within a single exposure period. Therefore, the electric light reception signal indicating the amount of light received for each wavelength output from the light receiving unit 140 is an average signal obtained by integrating the intensities of a plurality of lights for each wavelength. Thereby, the averaging process of a plurality of lights can be easily performed. The displacement of the measurement target S is calculated by the control unit 152 based on the light intensity after the averaging process.

  Light focused at a position different from the position of the surface of the measurement target S may pass through the optical fiber 314 due to irregular reflection on the surface of the measurement target S. Even in such a case, according to the above configuration, intensities of a plurality of lights passing through the optical fiber 314 for each wavelength are averaged in the averaging process. This cancels out light components that cause random measurement errors due to diffuse reflection. As a result, it is possible to reduce the error of the displacement of the measurement target S measured by the confocal displacement meter 500. Further, in this configuration, there is no need to perform an operation for performing the averaging process. Thereby, the displacement of the measurement target S can be calculated efficiently.

  Further, in the present embodiment, the tip portion of the optical fiber 314 functions as a pinhole. In this case, there is no need to separately arrange pinholes. Thus, the configuration of the confocal displacement meter 500 can be made compact.

  As described above, it is preferable that the clad 310b of the optical fiber 314 be a light shielding portion (pinhole member) and the core 310a be a pinhole. Thus, a confocal optical system can be realized with a simple configuration. On the other hand, if light loss can be tolerated, a light-shielding member provided with a plurality of pinholes in a light-shielding plate may be arranged at the end of the optical fiber 314 on the measurement head 200 side.

  Further, in the present embodiment, the processing device 100 and the first measuring head 200A are provided separately, and are optically connected by the light guide unit 300. Therefore, it becomes easy to use the first measurement head 200A including the lens unit 220 that generates appropriate chromatic aberration or the lens unit 220 having an appropriate focal length according to the shape or arrangement of the measurement target S. This makes it possible to more easily measure the displacement of the measurement target S.

  Further, a flat plate member 230 similar to the flat plate member 230 of the first measurement head 200A is disposed on the optical path of the second measurement head 200B. According to this configuration, the length of the optical path in the second measurement head 200B can be easily matched with the length of the optical path in the first measurement head 200A. Therefore, it is easy to configure the confocal optical system using the first measuring head 200A and the confocal optical system using the second measuring head 200B independently.

  In addition, since the light guide unit 300 includes an optical fiber, the processing device 100 and the measurement head 200 can be disposed separately. The second measuring head 200B is not provided with a mechanically driven component, and has no heat source. Therefore, the second measuring head 200B can be arranged in various environments. Further, as described later, by forming the exposed portion of the measurement head 200 with glass, the measurement head 200 can be arranged in more various environments.

  When a laser light source is used as the light source 121, it is preferable that the light guide unit 300 includes an optical fiber. For example, as shown in FIG. 9, when the phosphor 122 is excited by the laser light emitted from the light source 121 to generate light having a plurality of wavelengths, the light generated by using the optical fiber is efficiently used. Can be extracted well. Further, by using an optical fiber, the extracted light can be efficiently supplied to the measuring head 200.

(6) Modification Example (a) Modification Example of Driving Unit In the present embodiment, the driving unit 240 is realized by a hollow motor, but the present invention is not limited to this. The driving unit 240 may be realized by another actuator capable of moving the flat plate member 230, or may be realized by another configuration. FIG. 16 is a partial longitudinal sectional view showing a first modification of the driving section 240. As shown in FIG. 16, the driving section 240 according to the first modification includes a motor 243 and two rotors 244 and 245.

  The rotor 244 has a columnar shape, and is attached to the motor 243. A magnet 244M is provided on the outer peripheral surface of the rotor 244. The rotor 245 has a cylindrical shape, and a magnet 245M is provided on the inner peripheral surface of the rotor 245. The rotor 245 is arranged on a common axis with the rotor 244 such that the magnet 245M and the magnet 244M are separated from each other and oppose each other while exerting an attractive force, and held by a bearing (not shown). As a result, the rotor 245 is magnetically coupled to the rotor 244 so as to be rotatable while being separated from the rotor 244.

  The end of the optical fiber 314 is fixed to a hollow portion of the rotor 245 through a space between the rotor 244 and the rotor 245, for example, while being inserted into a ferrule (not shown). The flat plate member 230 is attached to the end of the rotor 245 in a state where the entrance surface 231 and the exit surface 232 are inclined with respect to a plane orthogonal to the optical axis of the optical fiber 314. According to this configuration, when the motor 243 rotates, the rotors 244 and 245 and the flat plate member 230 rotate. Thereby, the optical axis of the light emitted from the first measurement head 200A can be shifted.

  In the first modified example of the driving section 240, the rotor 244 and the rotor 245 are magnetically coupled, but the present invention is not limited to this. The rotor 244 and the rotor 245 may be electrically coupled, or may be coupled by another force in a non-contact manner.

  FIG. 17 is a partial vertical sectional view showing a second modification of the driving section 240. The difference between the driving unit 240 according to the second modification and the driving unit 240 according to the first modification will be described. As shown in FIG. 17, the drive unit 240 according to the second modification includes a power transmission member 246 instead of the magnets 244M and 245M. The rotor 244 and the rotor 245 are arranged on different axes that are substantially parallel. The power transmission member 246 is, for example, a belt and is stretched over the rotors 244 and 245. As a result, the rotor 245 is mechanically coupled to the rotor 244.

  According to this configuration, when the motor 243 rotates, the rotors 244 and 245 and the flat plate member 230 rotate. Thereby, the optical axis of the light emitted from the first measurement head 200A can be shifted. In the second modification of the driving section 240, the power transmission member 246 is realized by a belt, but the present invention is not limited to this. The power transmission member 246 may be realized by a chain, may be one or a plurality of gears arranged to transmit the rotational force of the rotor 244 to the rotor 245, or may be another member. Good.

(B) Modification of Lens Unit In the present embodiment, the lens unit 220 includes the refractive lens 221 and the diffractive lens 222, but the present invention is not limited to this. The lens unit 220 may not include one or both of the refractive lens 221 and the diffractive lens 222. FIGS. 18A to 18D are views showing first to fourth modified examples of the lens unit 220.

  As shown in FIG. 18A, the lens unit 220 in the first modification includes a diffraction lens 222 and an objective lens 223 without including the refractive lens 221 in FIG. As shown in FIG. 18B, the lens unit 220 according to the second modification includes a diffraction lens 222 and an objective lens 223 without including the refractive lens 221 in FIG. 1, as in the first modification. In the second modification, the positions of the diffraction lens 222 and the objective lens 223 in the first modification are opposite to those of the diffraction lens 222 and the objective lens 223 in the first modification.

  As shown in FIG. 18C, a lens unit 220 according to the third modification includes a doublet lens 224 instead of the diffraction lens 222 according to the first modification. As shown in FIG. 18D, the lens unit 220 according to the fourth modification includes a doublet lens 224 instead of the diffraction lens 222 according to the second modification.

  As described above, the lens unit 220 may be configured by, for example, a diffractive lens, a doublet lens, a GRIN (graded index) lens or a prism, or a combination thereof. According to the configuration of these lens units 220, it is possible to generate chromatic aberration along the optical axis direction in the light emitted by the light projecting unit 120 and converge the light having chromatic aberration to irradiate the measurement target S. it can.

  The above-described lens may be a glass lens, a resin lens, or a lens in which glass is processed with resin. Glass lenses have high heat resistance. The resin lens can be manufactured at low cost. Lenses in which glass is processed with resin can be manufactured relatively inexpensively and have relatively high heat resistance.

  Further, it is preferable that the lens of the lens unit 220 which is closest to the measurement target S is formed of glass. The measuring head 200 is arranged in an environment where moisture, oil, or the like exists in a manufacturing line such as a factory. By forming the optical system, such as a lens, of the portion exposed to the outside of the measurement head 200 from glass, the oil resistance, water resistance, and contamination resistance of the measurement head 200 can be improved.

  Similarly, it is preferable that a portion of the optical system of the lens unit 220 that is exposed to the outside air is formed of glass. Alternatively, the refractive lens 221, the diffraction lens 222, the objective lens 223, or the doublet lens 224 may be formed of resin instead of glass, and a portion of the lens unit 220 exposed to the outside may be formed of glass. For example, in the example of FIG. 18B, a cover glass may be provided below the diffraction lens 222 (on the measurement target S side).

(C) Modified Example of Light Projecting Unit In the present embodiment, the optical axis of light emitted from light source 121 and the central axis of ferrule 123 are arranged on a straight line, but the present invention is not limited to this. FIG. 19 is a diagram illustrating a modified example of the light projecting unit 120. As shown in FIG. 19, the light projecting unit 120 according to the modification includes a light source 121, a phosphor 122, a ferrule 123, lenses 124 and 128, and a reflecting member 129. The lens 124 is disposed between the light source 121 and the reflection member 129. The lens 128 is disposed between the reflection member 129 and the ferrule 123. The phosphor 122 is applied to the reflection surface of the reflection member 129.

  The light emitted by the light source 121 passes through the lens 124 and is condensed on the phosphor 122 applied to the reflecting member 129 as excitation light. The phosphor 122 absorbs the excitation light and emits fluorescence. Here, the excitation light transmitted without being absorbed by the phosphor 122 and the fluorescence from the phosphor 122 are mixed to generate light in a wide wavelength band. The generated light is reflected by the reflection surface of the reflection member 129, and is guided to the ferrule 123 through the lens 128. Thus, light is input to the optical fiber 311. In this configuration, the degree of freedom in arranging the optical elements is increased. Therefore, it is easy to reduce the size of the light projecting unit 120.

  In order to increase the intensity of light generated by the light projecting unit 120, it is preferable to increase the amount of light emitted by the light source 121. On the other hand, when the light amount of the light from the light source 121 is increased, the heat generated by the phosphor 122 is increased, so that the reflection efficiency of the reflecting member 129 is reduced and the emission of the fluorescence from the phosphor 122 is easily saturated. Therefore, the reflecting member 129 may be configured to be rotatable or movable. Thereby, the phosphor 122 is cooled, and heat generation can be suppressed. As a result, the intensity of the light generated by the light projecting unit 120 can be further increased.

(D) Modified Example of Dispersing Unit In the present embodiment, the diffraction grating 131 of the dispersing unit 130 has a reflection type, but the present invention is not limited to this. FIG. 20 is a diagram illustrating a modified example of the spectroscopy unit 130. As shown in FIG. 20, in a modified example of the light splitting unit 130, the diffraction grating 131 has a transmission type. The light incident on the diffraction grating 131 is split so as to be transmitted at different angles for each wavelength. The light split by the diffraction grating 131 passes through the lens 133 and is focused on a pixel position of the light receiving unit 140 which differs for each wavelength.

(7) Other Embodiments (a) In the above embodiment, the light guide unit 300 includes an optical fiber, and light is transmitted between the processing device 100 and the measurement head 200 using the optical fiber. The present invention is not limited to this. The light guide unit 300 does not include an optical fiber, and light may be transmitted between the processing apparatus 100 and the measurement head 200 using an optical element such as a mirror and a half mirror.

  FIG. 21 is a schematic diagram showing a configuration of a confocal displacement meter according to another embodiment. In FIG. 21, as shown in FIG. 21, the light guide unit 300 includes a half mirror 371 and a plurality (two in this example) instead of the optical fibers 311 to 314, the fiber coupler 320, and the fiber connector 330 of FIG. Are included. Pinholes 372a and 373a are formed in the spatial filters 372 and 373, respectively.

  The light emitted from the light projecting unit 120 passes through the pinhole 372 a of the spatial filter 372 and then passes through the half mirror 371. The light that has passed through the half mirror 371 is applied to the measurement target S through the flat plate member 230 and the lens unit 220. Part of the light reflected on the surface of the measurement target S passes through the flat plate member 230 and the lens unit 220, and is reflected by the half mirror 371. The light reflected by the half mirror 371 passes through the pinhole 373 a of the spatial filter 373 and is guided to the light splitting unit 130. The light receiving unit 140 receives the light separated by the light separating unit 130 and outputs a light receiving signal.

  The arithmetic processing unit 150 acquires the light receiving waveform W0 on which the averaging process has been performed, based on the light receiving signal output by the light receiving unit 140. As described above, by performing the averaging process of the received light waveform W0, a light component that generates a random measurement error due to irregular reflection is canceled. By specifying the peak wavelength λ0 of the light reception waveform W0, the measurement distance can be specified more accurately.

  (B) In the above embodiment, the light projecting unit 120 of FIG. 9 or FIG. 19 emits light in a wide wavelength band by mixing the excitation light from the light source 121 and the fluorescence from the phosphor 122. The invention is not limited to this. The light projecting unit 120 may include a light source that emits light in a wide wavelength band, instead of the light source 121 and the phosphor 122. For example, the light projecting unit 120 may include an LED (light emitting diode) or a halogen lamp that emits white light as a light source.

  (C) In the above embodiment, the light projecting unit 120 emits light having a continuous wavelength of 500 nm to 700 nm, but the present invention is not limited to this. The light projecting unit 120 may emit light of another wavelength band having a continuous wavelength. For example, the light projecting unit 120 may emit light in the infrared region having a continuous wavelength, or may emit light in the ultraviolet region having a continuous wavelength.

  (D) In the above embodiment, the processing apparatus 100 and the measurement head 200 are configured as separate bodies, but the present invention is not limited to this. The processing device 100 and the measurement head 200 may be integrally configured.

  (E) In the above embodiment, light is coupled and branched using the fiber coupler 320, but the present invention is not limited to this. Instead of using the fiber coupler 320, the coupling and branching of light may be performed using a plurality of optical fibers 311 to 313 in which a plurality of cores 310a are fused together.

  (F) In the above embodiment, optical integration processing is performed as averaging processing of the received light waveform W0, but the present invention is not limited to this. As the averaging process of the received light waveform W0, an electrical integration process, an averaging process, or a weighted averaging process may be performed, or another process may be performed.

  For example, the light receiving unit 140 may sequentially receive the plurality of lights sequentially split by the spectroscopic unit 130 and output a light receiving signal for each of the plurality of sequentially received lights. In this case, the control unit 152 calculates an average signal as a signal intensity for each wavelength by averaging or integrating a plurality of light reception signals output from the light receiving unit 140 for each wavelength, and based on the calculated average signal. The displacement of the measurement target S can be calculated.

  Alternatively, the light receiving unit 140 may receive a plurality of lights sequentially split by the spectroscopic unit 130 in a plurality of exposure periods, and output a light reception signal for the light received in each exposure period. In this case, the control unit 152 calculates an average signal as a signal intensity for each wavelength by averaging or integrating a plurality of light reception signals output from the light receiving unit 140 for each wavelength, and based on the calculated average signal. The displacement of the measurement target S can be calculated. According to these configurations, it is possible to perform a desired calculation in consideration of the intensities of a plurality of lights in calculating the average signal. Thereby, the displacement of the measurement target S can be calculated more accurately.

  (G) In the above embodiment, the flat plate member 230 is disposed between the optical fiber 314 and the lens unit 220, but the present invention is not limited to this. The flat plate member 230 may be arranged at any position on the optical path.

  (H) In the above embodiment, the confocal displacement meter 500 includes both the first measurement head 200A and the second measurement head 200B, but the present invention is not limited to this. The confocal displacement meter 500 may include the first measurement head 200A and may not include the second measurement head 200B. Alternatively, when measuring the displacement of the measurement target S having a small degree of irregular reflection, the first measurement head 200A may be used in a state where the rotation of the driving unit 240 of the light irradiation unit 1 is stopped. In this case, the principle of displacement measurement using the first measurement head 200A is the same as the principle of displacement measurement using the second measurement head 200B.

(8) Correspondence relationship between each component of the claims and each unit of the embodiment Hereinafter, an example of correspondence between each component of the claims and each unit of the embodiment will be described. Not limited.

  In the above embodiment, the measurement object S is an example of the measurement object, the confocal displacement meter 500 is an example of the confocal displacement meter, the light projecting unit 120 is an example of the light projecting unit, 1 is an example of a light irradiation unit. The spectral unit 130, the light receiving unit 140, and the arithmetic processing unit 150 are examples of a displacement measuring unit, the spectral unit 130 is an example of a spectral unit, the light receiving unit 140 is an example of a light receiving unit, and the arithmetic processing unit 150 is a calculating unit. And the irradiation region IR is an example of the region. The driving unit 240 is an example of a driving unit, the processing device 100 is an example of a processing device, the power supply unit 160 is an example of a power supply unit, the optical fiber 314 is an example of an optical fiber, and the core 310a is a core. The light source 121 is an example of a light source, and the phosphor 122 is an example of a phosphor.

  The first measurement head 200A and the second measurement head 200B are examples of first and second head units, respectively, and the lens unit 220 of the first measurement head 200A is an example of a first optical member. The lens unit 220 of the second measurement head 200B is an example of a second optical member, and the optical fiber 314 or the spatial filter 373 of the first measurement head 200A is an example of a first pinhole member. The optical fiber 314 or the spatial filter 373 of the second measuring head 200B is an example of a second pinhole member, and the tip portion or the pinhole 373a of the optical fiber 314 of the first measuring head 200A is an example of a first pinhole. is there.

  The tip portion or the pinhole 373a of the optical fiber 314 of the second measuring head 200B is an example of a second pinhole, the flat plate member 230 of the first measuring head 200A is an example of a first light transmitting portion, and the second The flat plate member 230 of the measuring head 200B is an example of the second light transmitting part. The entrance surface 231 and the exit surface 232 of the flat plate member 230 of the first measurement head 200A are examples of first and second surfaces, respectively, and the entrance surface 231 and the exit surface 232 of the flat plate member 230 of the second measurement head 200B are respectively It is an example of the third and fourth surfaces. The housing 110 is an example of a first housing, the housing 210 of the first measurement head 200A is an example of a second housing, and the housing 210 of the second measurement head 200B is an example of a third housing. It is an example.

  Various other elements having the configuration or function described in the claims may be used as the constituent elements in the claims.

  The present invention can be effectively used for various confocal displacement meters.

Reference Signs List 1 light irradiation unit 100 processing device 110, 210 housing 120 light emitting unit 121 light source 122 phosphor 123 ferrule 124, 128, 132, 133 lens 125 holder 126 filter element 127 element holder 127A light source fixing unit 127B ferrule fixing unit 127C lens Fixed unit 129 Reflecting member 130 Beam splitting unit 131 Diffraction grating 140 Light receiving unit 150 Operation processing unit 151 Storage unit 152 Control unit 160 Power supply unit 170 Display unit 200 Measurement head 200A First measurement head 200B Second measurement head 220 Lens unit 221 Refractive lens 222 Diffractive lens 223 Objective lens 224 Doublet lens 230 Plate member 231 Incident surface 232 Emitting surface 240 Drive unit 241 Fixed unit 242 Rotation axis 243 Motor 244, 245 Rotor 2 4M, 245M Magnet 246 Power transmission member 300 Light guide 310a Core 310b Clad 311 to 314 Optical fiber 320 Fiber coupler 321 to 323, 331, 332 Port 324, 333 Main body 330 Fiber connector 371 Half mirror 372, 373 Spatial filter 372a, 373a Pinhole 400 Control device 401 Display device 402 Operation unit 403 CPU
404 Memory 491 Switching button 500 Confocal displacement meter BL Base waveform IR Irradiation area MR Measurement range OD Outer diameter P0, Px to Pz Peak P1, P2 Focus position RP Reference position S Measurement object W0 to W4 Light reception waveform λ0 to λ4 λx, λy Peak wavelength

Claims (14)

A confocal displacement meter that measures a displacement of a measurement object using a confocal optical system,
A light emitting unit that emits light having a plurality of wavelengths,
The light emitted from the light projecting unit is provided on a first optical path, and the light emitted to the object to be measured is shifted by sequentially shifting the optical axis of the light emitted by the light projecting unit. A light irradiation unit that sequentially shifts in a direction orthogonal to the optical axis to sequentially irradiate a plurality of continuous or intermittent portions of the measurement object,
A first optical member that generates chromatic aberration along the optical axis direction in light irradiated on the measurement object by the light irradiation unit, and converges light having chromatic aberration;
A first pinhole member having a first pinhole that sequentially passes light having a wavelength reflected while being focused on the plurality of portions of the measurement object,
The displacement of the measurement object is calculated based on the signal intensity for each wavelength of the average signal corresponding to the average of the intensity for each wavelength of the plurality of lights corresponding to the plurality of portions sequentially passing through the first pinhole. A confocal displacement meter, comprising: The displacement measuring unit,
A light splitting unit that sequentially splits a plurality of lights corresponding to the plurality of portions that sequentially pass through the first pinhole;
A plurality of light receiving in a single exposure period, electrical receiving signal to the average signal indicating the received light amount for each wavelength for the received light corresponding to said plurality of portions are sequentially split by the spectroscopic unit A light-receiving unit that outputs as
The confocal displacement meter according to claim 1, further comprising: a calculating unit that calculates a displacement of the measurement target based on the average signal. The displacement measuring unit,
A spectroscopy unit for sequentially separating a plurality of lights sequentially passing through the first pinhole;
A light receiving unit that sequentially receives a plurality of lights sequentially split by the splitting unit and outputs an electric light receiving signal indicating a received light amount for each wavelength for each of the plurality of sequentially received lights,
Wherein calculating the average signal a plurality of light receiving signals output from the light receiving unit as a signal strength for each of the wavelengths by averaging or integrating for each wavelength, and calculates the displacement of the measurement object based on the average signal The confocal displacement meter according to claim 1, further comprising a calculating unit. The displacement measuring unit,
A light splitting unit that sequentially splits a plurality of lights corresponding to the plurality of portions that sequentially pass through the first pinhole;
An electrical light receiving signal that receives a plurality of lights corresponding to the plurality of portions sequentially divided by the spectroscopic unit within a plurality of exposure periods , and indicates a light reception amount for each wavelength of the light received in the plurality of exposure periods; A light receiving unit that outputs
Wherein calculating the average signal as the signal strength for each of the wavelengths by averaging or integrating a plurality of light receiving signals corresponding to the plurality of exposure periods output from the light receiving unit for each wavelength, on the basis of the said average signal The confocal displacement meter according to claim 1, further comprising a calculating unit that calculates a displacement of the measurement target. The light irradiation unit is configured to set the optical axis of the light emitted by the light projecting unit to the surface of the measurement object so that the light is applied to a plurality of portions on an annular region on the surface of the measurement object. The confocal displacement meter according to any one of claims 1 to 4, wherein the confocal displacement meter is shifted along. The confocal displacement meter according to claim 5, wherein an outer diameter of the annular region is 100 µm or more. The confocal displacement meter according to claim 5, wherein an outer diameter of the annular region is 500 μm or less. The light irradiation unit,
A first light-transmitting portion formed of a light-transmitting member and having first and second surfaces;
And a driving unit, wherein at least one of the first and second surfaces of the first light transmitting unit is disposed on a surface orthogonal to the first optical path of the light emitted by the light projecting unit. Disposed on the first optical path in a state of being inclined,
The driving unit according to claim 5, wherein the driving unit is configured to rotate the first and second surfaces of the first light transmitting unit in a plane intersecting the first optical path. The confocal displacement meter according to the paragraph. A processing unit;
And a first head unit,
The processing device includes the light emitting unit and the displacement measuring unit, and further includes a first housing that houses the light emitting unit and the displacement measuring unit,
The said 1st head part contains the said light irradiation part and the said 1st optical member, and further includes the 2nd housing | casing which accommodates the said light irradiation part and the said 1st optical member. Confocal displacement meter. The processing device further includes a power supply unit housed in the first housing,
The confocal displacement meter according to claim 9, wherein the power supply unit is connected to the light irradiation unit so as to be able to supply power to the driving unit of the first head unit. A second head portion;
A second pinhole member having a second pinhole,
The second head section includes:
A second optical member that generates chromatic aberration along the optical axis direction in the light emitted by the light projecting unit, and converges the light having chromatic aberration to irradiate the measurement target object,
A second light-transmitting portion formed of a light-transmitting member and having third and fourth surfaces;
A third housing accommodating the second optical member and the second light transmitting unit,
At least one of the third and fourth surfaces of the second light-transmitting portion is inclined with respect to a surface orthogonal to a second optical path of the light emitted by the light projecting portion. Disposed on the second optical path,
The second pinhole allows light of a wavelength reflected by the second optical member of the second head portion while being focused on the surface of the measurement target,
The displacement measuring unit calculates a displacement of the measurement target based on a signal intensity for each wavelength of light that has passed through the second pinhole,
The confocal displacement meter according to claim 9, wherein the light emitted by the light projecting unit is selectively guided to the first head unit and the second head unit. Further comprising an optical fiber,
The optical fiber guides the light emitted by the light projecting unit to the first optical member, and sequentially passes through the first pinhole by being reflected by the plurality of portions of the measurement object. The confocal displacement meter according to claim 1, wherein the confocal displacement meter is provided to guide a plurality of lights to the displacement measurement unit. 13. The confocal displacement meter according to claim 12, wherein an end of the optical fiber is the first pinhole. The light emitting unit is
A light source that emits light of a single wavelength,
14. A confocal according to claim 1, further comprising: a phosphor that absorbs light emitted by the light source and emits light having a wavelength different from the wavelength of the light emitted by the light source. Displacement gauge.

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