JPH01250008A - Aspherical shape measuring instrument - Google Patents

Abstract

PURPOSE:To measure the shape of an objective surface by holding the body to be measured and rotating a theta stage and inputting the current angle of rotation, the output of an optical displacement sensor, and the output of an X- directional movement quantity detecting means. CONSTITUTION:The body 21 held by a holding mechanism 20 on the theta stage 10 is set so that the center of curvature of the surface 21a to be measured meets the center of rotation of the theta stage 10; while the theta stage 10 is rotated in this state, the current angle of rotation the current position thetar of the theta stage 10 from the rotation angle detecting means 33 composed of a rotary encoder 18 and an angle detecting circuit 43, the output l1 of the optical displacement sensor 31, and the output l1s of an (x)-directional movement quantity detection body 33b are inputted to a signal processing means 46 at the same time. A series of processes are carried on until the theta stage 10 is rotated by a specific angle. When the signal processing means 46 performs arithmetic (l1+l2) at intervals of an angle thetar of rotation to obtain shape data on the surface 21a to be measured.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an aspherical surface shape measuring device used in the surface shape inspection process of concave lenses, convex lenses, molds, etc. This invention relates to an improvement of an aspherical surface shape measuring device that non-contactly measures the spherical and aspherical shapes of the surface of an object.

(Problems to be Solved by the Prior Art and the Invention) Conventionally, as means for measuring the spherical or aspherical shape of objects to be measured such as lenses, there have been two methods: ■ interferometry; There are two methods: (1) a measurement method that utilizes interference between the reflected light from the object to be measured and a reference surface; and (2) a measurement method that utilizes the straightness of light and the law of reflection.

In the interferometer n1 method described in (2) above, light from a light source is irradiated onto the prototype and the measured object, and the reflected light waves from the reference surface of the prototype at that time and the reflected light waves from the measured surface of the measured object are interfered. This method measures the shape of the surface to be measured by analyzing the interference fringes obtained.

Next, it is a combination of the Jarring interferometry and the fringe scanning interferometry mentioned above. Among these, the Jarring interferometry divides the wavefront to be measured into two, shifts one wavefront laterally with respect to the optical axis, and the other wavefront This is a method of interfering with On the other hand, the fringe scanning interferometry is a method in which a piezo element is attached to a reference mirror, and the phase of the reference light wave of the reference mirror is changed using the light wave of the surface to be measured. The measuring method (2) above measures the shape of the surface to be measured using the above two measuring methods.

In addition, in the measurement method (2) above, the shape of the surface to be measured is determined by dividing the laser beam into two, irradiating one side on the surface to be measured, and irradiating the other on the reference surface, and making the reflected lights from each interfere. It is a method of measurement.

Furthermore, the method using the straightness of light and the law of reflection (2) takes advantage of the properties of specular reflection of a light beam, in which the light beam is incident on the surface to be measured, and the direction of incidence and the surface to be measured at the point of incidence are This measurement method is based on the property that when the normal directions of the reflected light beam and the incident light beam match, the reflected light beam returns along the same optical path as the incident light beam. That is, the shape of the surface to be measured is measured by moving the surface to be measured so that the incident light beam and the reflected light beam are on the same optical path and detecting the amount of movement.

(Problems to be Solved by the Invention) However, among the above measurement methods, the interferometric measurement method (2) not only requires a prototype as a reference surface, but also requires a high-precision reference surface with an aspherical shape. It is very difficult to manufacture it and it is also expensive. Furthermore, when the deviation between the wavefront generated from the reference surface and the wavefront generated from the measured surface becomes large, a large number of interference fringes occur, making shape analysis difficult. In addition, only mirror surfaces can be measured, and it is impossible to measure optically rough surfaces.

In this regard, the measurement method described in ■■■ does not require a prototype as a reference surface, but it does require a highly accurate movement mechanism and alignment mechanism, although high accuracy cannot be expected in principle. The entire optical system is complex.

It becomes expensive.

In addition, if the surface to be measured is optically rough, there is a problem in that measurement method (■) above cannot be used because interference fringes cannot be obtained. High precision measurements are not possible.

The present invention was made to solve the above-mentioned problems, and enables high-accuracy, high-speed measurement of spherical and aspherical shapes with a simple measurement method, and can be easily measured even when the surface to be measured is rough. An object of the present invention is to provide an aspherical shape measuring device that can measure the shape of an aspherical surface.

Another object of the present invention is to eliminate the influence of periodic fluctuations in the rotational axis of the θ stage that holds and rotates the object to be measured, even if the rotational axis changes periodically depending on the rotation angle. An object of the present invention is to provide an aspherical surface shape measuring device that can accurately measure the shape of an object to be measured.

Furthermore, another object of the present invention is that even when the surface to be measured deviates significantly from the design value and becomes uneven, or when the center of curvature of the surface to be measured and the center of rotation of the θ stage are set to be misaligned, To provide an aspherical surface shape measuring device that measures the optical displacement sensor scanning route of the surface to be measured without deviating from the detection point of the optical displacement sensor, and reliably measures the shape of the surface to be measured. There is a particular thing.

(Means for Solving the Problems) In order to achieve the above object, an aspherical surface shape measuring device according to the present invention includes a θ stage that holds an object to be measured and rotates around the center of curvature at the center of the surface to be measured. , an angle detection means for detecting the rotation angle of the θ stage, an optical displacement sensor disposed opposite to the surface to be measured of the object to be measured and detecting the displacement of the surface to be measured, and the optical displacement sensor for detecting the displacement of the surface to be measured. An X stage to be moved in a direction facing the measurement surface, a movement amount detection means for detecting the movement amount of the X stage, an output of the angle detection means, an output of the optical displacement sensor, and an output of the movement amount detection means. and signal processing means that simultaneously receives the signals and determines the shape of the surface to be measured.

In addition to the above-mentioned means, the apparatus of the present invention also includes rotational axis fluctuation amount detection means for detecting periodic fluctuations in the rotational axis of the θ stage by setting a prototype on the θ stage, and A rotation axis center fluctuation amount correction means is added for correcting the measured amount of the object to be measured using the amount of rotation axis fluctuation amount obtained by the amount detection means.

In addition, the θ stage is provided with an X'X stage that moves the object to be measured in a direction facing the optical displacement sensor, and the X'X stage is moved to align the center of curvature of the object to be measured with the center of rotation of the θ stage. It is equipped with the following.

Further, the θ stage is provided with an α stage that rotates the object to be measured about a line connecting the center of curvature of the object to be measured and the center of the surface to be measured as the rotation axis.

Furthermore, by providing an autofocus circuit for the output of the optical displacement sensor and moving the optical displacement sensor via the X stage according to the output state of the optical displacement sensor, the optical displacement sensor is always kept at a predetermined distance from the surface to be measured. It has a configuration to set it.

(Function) Therefore, by using the above-described means, the device of the present invention, after holding the object to be measured on the θ stage, detects the angle while rotating the surface to be measured from the reference angle position via the rotation stage. The rotation angle is sequentially detected by the means. on the other hand,
An unevenness signal of the surface to be measured is taken out from the optical displacement sensor, and a sensor position signal is taken out from the movement amount detection means. Then, based on the rotation angle obtained by the angle detection means, the output of the optical displacement sensor and the output of the movement amount detection means are taken in to determine the shape of the surface to be measured.

In addition, when there is a periodic fluctuation in the rotation axis of the θ stage depending on the rotation angle, this device holds the prototype on the θ stage and detects the output of the optical displacement sensor and the movement amount detection means for each rotation angle. By taking in the output and storing it in a memory table as a correction value, and subsequently correcting the measurement data of the object to be measured, the influence of the amount of variation in the rotation axis of the θ stage is removed.

(Example) Hereinafter, FIGS. 1 to 5 will explain an example of the apparatus of the present invention.
This will be explained with reference to the figures. Fig. 1 is an overall configuration diagram of the aspherical surface shape measuring device schematically showing the mechanical part, Fig. 2 is a sectional view showing the holding mechanism of the object to be measured, and Fig. 3 (a) shows a closer view of the mechanical part of the device. A detailed front view, Figure (b) is a top view, Figure 4 is a diagram of the relationship between changes in the surface to be measured and the light receiving position of the luminous intensity position sensor, and Figure 5 is a diagram of the optical displacement sensor and movement amount detection. It is a figure explaining the relationship with a means.

In these figures, 10 is a θ stage with a built-in air bearing that is rotatably mounted on a frame 11.

When the pulse motor 12 attached to the lower part of the frame 11 rotates, the θ stage 10 rotates.
The frame 1 passes from the pulley 13 directly connected to the rotating shaft of the
The transmission is transmitted to a pulley 16 that is directly connected to a rotating shaft 15 that penetrates through the inside of the frame and extends to the lower side of the frame, and rotates at a predetermined angle or continuously. A rotary encoder 18, which constitutes a part of rotation angle detection means, is provided on the rotation shaft 15 via a coupling 17. 1
9 is an output shaft system of the θ stage 10.

Reference numeral 20 denotes an object holding mechanism for mounting the object 21 on the output shaft system 19 of the θ stage 10.

That is, the object to be measured 21 is held by the holding mechanism 20 so as to rotate about the center of curvature at the center of the surface to be measured by the holding mechanism 20 when the θ stage 10 rotates. In this holding mechanism 20, for example, as shown in FIG. 2, a holding base 22 having a threaded portion 22a provided on the outer periphery is attached to one side of the output shaft system 19. A pair of mounts 23 and 24 are disposed on the front side of the holding base 22 and are screwed together, sandwiching the outer peripheral edge of the object to be measured 21, and are engaged with the mount 23 located inside. The annular outer body 25 in the state is attached to the threaded portion 22' of the holding base 22.
By screwing the object to be measured 21 to the output shaft system 19
are fixed in a predetermined positional relationship. Note that the holding base 22. The shape, size, etc. of the mounts 23, 24 are varied depending on the outer diameter, size, etc. of the object 21 to be measured.

Reference numeral 30 denotes an X stage that is located on the frame 11 and moves in a direction facing the surface to be measured of the object to be measured 21, and an optical displacement sensor 31 is mounted on the X stage 30 so as to face the surface to be measured. is installed. 32 is X stage 3
This is a motor that moves 0.

As shown in FIG. 3(a), the optical displacement sensor 31 has a front side forming a V-shaped surface in the vertical direction, and a laser beam is irradiated from one side 31a of the V-shaped surface to
The reflected light and scattered light from the surface to be measured are transferred to the other surface portion 31b.
It is a non-contact sensor that uses, for example, a laser beam as a probe, and has the function of detecting the distance due to the unevenness of the surface to be measured 21a based on the principle of triangulation, as shown in FIG. . That is, when the reference distance between the surface to be measured 21a and the end surface of the optical displacement sensor 31 is a predetermined distance of 0, the optical displacement sensor 31 outputs zero, for example, the surface to be measured 21
It has a function of linearly outputting +M to -M when the position of a is changed by the distance indicator no to -no as shown by the dotted line in the figure.

Reference numeral 33 denotes a movement amount detection means for detecting the amount of movement of the X stage 30 in the X direction. It is composed of a movement signal generator 33a and an X-direction movement amount detector 33b that is provided separately from the X stage 30 and detects the amount of movement in the X direction.

The positional relationship between the optical displacement sensor 31 and the movement amount detection means 33 is as follows. The θ stage 10 is placed on a plane formed by the irradiation optical axis and the light receiving axis of the laser beam of the optical displacement sensor 31.
The output shaft system 19 is positioned such that the optical displacement sensor 31 is located at the reference distance.

The locus of point aO where the output displacement becomes zero is output shaft system 1.
9(z). In addition, two-axis 19
Since there is a distance is between the point aO and the point aO, if the distance equivalent to this distance is set in advance on the movement amount detection means 33 side as the movement distance, the output of the optical displacement sensor 31 and the movement amount detection means 3 can be set in advance.
By adding the outputs of 3 and 3, the shape of the object to be measured 21 can be expressed.

In FIG. 1, 41 is a controller, 42 is a driver that receives a drive command from the controller 41 and drives the pulse motor 12, 43 is an angle detection circuit that converts the output of the row encoder 18 into a required angle signal, and 44
The driver 45 operates manually or receives an external signal.
This is a controller that drives the X-direction movement motor 32 via the X-direction moving motor 32. 46 is a signal processing means that simultaneously takes in the output of the angle detection circuit 43, the output 1 of the optical displacement sensor 31, and the output 12 of the X-direction movement amount detector 33b, and for each rotation angle ()1+J! 2) performs the calculation process, and
A calculation process is performed to obtain a shape deviation from this calculation result and the radius of curvature R, and the calculated shape deviation is output to an output device.

Next, the operation of the apparatus configured as above will be explained. First, after fixing the holding base 22 to the output shaft system 19 of the θ stage 10, the mount 23 is attached to this holding base 22.
．． The object to be measured 21 is held by an outer body 24, an outer body 25, and the like. At this time.

The object to be measured 21 is mounted so that the center of curvature of the surface to be measured 21a coincides with the center of rotation of the θ stage 10.

Subsequently, the X stage 30 is moved in the X direction by outputting a drive command from the controller 44 and driving the X direction movement motor 32. A point ao where the output of the optical displacement sensor 31 becomes zero due to the movement of the X stage 30 in the X direction.
+That is, the optical displacement sensor 31 is set to the reference position.

Thereafter, by outputting a drive command from the controller 41 and driving the pulse motor 12, the surface to be measured 21 of the object to be measured 21 is moved from the reference angular position via the θ stage 10.
Rotate g. At this time, the laser beam is irradiated onto the surface to be measured 21a from one of the 7-shaped surfaces of the optical displacement sensor 31, that is, from the irradiation surface portion 31a side, and the reflected light or scattered light from the surface to be measured 21a at this time is transferred to the other light receiving surface portion 31b. Receive light from the side.

During this rotation of the θ stage 10, the signal processing means 46 detects the current position θr1 of the θ stage 10 from the rotation angle detection means composed of the row encoder 18 and the angle detection circuit 43.
The output 1 of the optical displacement sensor 31 and the outputs S and S of the X-direction movement amount detector 33b are simultaneously received and stored in a memory (not shown), and this series of processing is performed until the θ stage 10 rotates by a predetermined angle. I can continue. This signal processing means 4
6, for each rotation angle θr of the θ stage 10 ()
1+12) is performed to obtain shape data of the surface to be measured 21a. Thereafter, the shape deviation is determined based on (), +2) for each position θr and the radius of curvature (reference value) R, and is output to the output device.

Therefore, according to the configuration of the embodiment described above, the object to be measured 21 held by the holding mechanism 20 on the θ stage 10 is held such that the center of curvature of the surface to be measured 21a coincides with the center of rotation of the θ stage 10. and set the optical displacement sensor 31 to the reference position, and while rotating the θ stage 10 in this state, simultaneously capture the rotation angle, the output of the optical displacement sensor 31, and the output of the X-direction movement amount detection means. As a result, the shape of the surface to be measured 21a can be easily measured from these signals, and can be measured without using a prototype.

Furthermore, the shape of the surface to be measured 21a can be obtained using the output of the optical displacement sensor 31 or the like as is, which greatly simplifies signal processing. Furthermore, since the only moving mechanisms are the θ stage 10 and the X stage 30, and there are fewer optical elements, the mechanism and optical system can be significantly simplified compared to conventional devices without prototypes. In addition, since measurement is performed using the principle of triangulation using the optical displacement sensor 31 while rotating the surface 21a to be measured, it is possible to measure the shape of the entire circumference of not only a convex lens but also a concave lens. Even if the object 21 has an uneven shape, its shape can be easily measured by receiving the scattered light.

In the above embodiment, the output shaft system 19 on the θ stage 10 is provided with the holding mechanism 20 that holds the object to be measured 21;

Depending on the size, etc., the center of curvature of the object to be measured 21 and the center of rotation of the θ stage 10 may not coincide with each other. In such a case, as shown in FIG. 6, an X'X stage 40 that moves in the direction X' facing the optical displacement sensor 31 is provided on the θ stage 10, and an output shaft system 19' is mounted on this X' stage 40. If the configuration is such that the center of curvature and the center of rotation can be made to coincide with each other. Specifically, an elongated concave member 42 is placed on the θ stage 10 via an intermediate member 41, and a block 44 is engaged with a screw body 43 hooked between both sides of the concave member 42. Furthermore, an output shaft system 19 is installed on this block 44.

Therefore, with this configuration, if the screw body 43 is rotated clockwise or counterclockwise by a motor or the like from the outside, the output shaft system 19 will move in the X' direction via the block 44. Even if the shape, size, etc. of the object to be measured 21 changes, it is possible to make the center of curvature of the object to be measured 21 coincide with the center of rotation of the θ stage 10.

Further, an X'X stage 40 is provided on the θ stage 10 to move the object to be measured 21 in the X' direction, but for example, as shown in FIG. If the α stage 50 is provided and the object to be measured 21 is rotated with the line connecting the center of curvature of the object to be measured 21 and the center of the object to be measured 21 as the rotation center, the object to be measured 21 can be driven in the direction of the arrow shown in FIG. 7(a). On the other hand, the surface to be measured 21 is scanned with scanning lines as shown in FIG.
a can be scanned, and the measurement range can be expanded accordingly.

Furthermore, as another embodiment, when the θ stage 10 reaches a predetermined rotation angle using an angle detection means consisting of the rotary encoder 18 and the angle detection circuit 43, the α stage 50 is adjusted based on the embodiment of FIG. By rotating the object 21, the object 21 can be scanned with scanning lines as shown in FIG. 8, and the scanning range of the object 21 can be expanded as in the embodiment shown in FIG. Note that at this time, it is necessary to detect the rotation angle of the α stage 50 with the rotation detector 51 and send this angle detection signal to the signal processing means 46.

Next, as another embodiment, an example in which an autofocus function is provided will be described. Generally, the surface shape of the object to be measured 21 is relatively close to a perfect circle as shown in FIG. 9, and
When the radius of curvature of the object to be measured 21 and the center of rotation of the θ stage 10 match, there is little variation in the object to be measured 21 even when the θ stage 10 is rotated, so autofocus is not necessary.

However, if the surface shape of the object to be measured 21 deviates significantly from the design value and becomes uneven, or if the center of curvature of the surface to be measured and θ
If the center of rotation of the stage is set out of alignment,
As shown in Figure 10, the position of the measurement point shifts in the circumferential direction,
Also, it jumps out of the 4-1 fixed range of the highly sensitive displacement sensor.

Therefore, when measuring the shape of the object to be measured 21, an autofocus function is required, as described below.

This will be explained with reference to FIGS. 11 and 12. In FIG. 12, the same parts as in FIG. 1 are given the same reference numerals, and detailed explanation thereof will be omitted. That is, this autofocus means includes an autofocus circuit 60 between the output side of the optical displacement sensor 31 and the controller 44, and when the surface shape of the object to be measured 21 changes from the solid line to the dotted line in FIG. Output of displacement sensor 31 and predetermined setting value S
The deviation signal is sent to the controller 44, the X stage 30 is moved backward, and the laser beam is irradiated to the dotted line position in FIG. 11 to adjust the sensor output to the set value Sv. This configuration eliminates positional deviation.

Therefore, according to the configuration of this embodiment, an autofocus circuit 60 is provided, and by controlling the movement of the X stage 3° so that the output of the optical displacement sensor 3°1 always becomes a predetermined value, the optical displacement sensor 31 The condition of the surface to be measured 21a can be measured by always setting it at a predetermined position from the surface to be measured 21a, especially when there are large changes in the unevenness of the surface shape or when the center of curvature of the object to be measured and the center of rotation of the θ stage are misaligned. The shape of the object to be measured 21 can be accurately measured even when the object 21 is present.

Next, another embodiment of the present invention will be described with reference to FIGS. 12 to 15. usually.

Periodic fluctuations depending on the rotation angle of the rotation axis of the θ stage 10 are generally negligible when the mounting height H of the object to be measured 21 is low, but as H becomes higher, the amount of fluctuation decreases. When d becomes large, a so-called scratching phenomenon occurs, which cannot be ignored when submicron precision is required by actual users.

Therefore, in this embodiment, the output shaft system 19 of the θ stage lO is
It is possible to attach a prototype 70 that shows roundness to the signal processing means 46, and a memory table 71 for storing data collected when the prototype 70 is attached is connected to the signal processing means 46. Functionally, the output of the angle detection means when the prototype 70 is mounted on the θ stage 10, the output of the optical displacement sensor 31, and the output of the X-direction movement amount detector 33b are stored in the memory table 46. 71 , a measuring surface displacement amount obtaining means 73 which attaches the object 21 to the θ stage 10 and similarly obtains the required signal, and stores the data stored in the memory table 71 . The rotary shaft center fluctuation amount correcting means 75 is used to correct the fluctuation amount.

Therefore, with the above configuration, first, after attaching the prototype 70 to the output shaft system 19 of the θ stage 10, the θ stage 10 is rotated in the same manner as described above, and the rotation angle at that time is determined by the rotary encoder 18. The angle detection circuit 43 converts the signal into a desired angle signal, and then sends it to the signal processing means 46.

On the other hand, the reference surface of the prototype 70 is irradiated with laser light from the optical displacement sensor 31, and the light reflected from the reference surface is received by the sensor light receiving surface. Then, the rotational angle signal outputted from the angle detection means, the output of the optical displacement sensor 31, and the output of the X-direction movement amount detection body 33b are simultaneously captured in the rotational axis fluctuation amount detection means 72 of the signal processing means 46 and sequentially stored. It is stored in table 71. .

As a result, the memory table 71 stores the amount of variation d−f (θ
) is obtained.

Thereafter, the prototype 70 is removed from the θ stage 10, and the object to be measured 21 is attached to the output shaft system 19 of the θ stage 10 via the holding mechanism 20. Thereafter, the measurement surface displacement amount acquisition means 73 acquires the rotation angle of the θ stage 10, the output of the optical displacement sensor 31, and the X-direction movement amount detector 33b in the same manner as described above.
This process is sequentially repeated for each rotation angle to collect the required signals. Then, the calculation (, il' x +12) is performed for each rotation angle.

Thereafter, the data of the prototype 70 stored in the memory table 71 is subtracted from the data of the calculation result in the rotational axis fluctuation amount correction means 74 to remove the fluctuation amount of the rotational axis of the θ stage 10. The shape deviation is obtained from the radius of curvature R of the object 21, and the shape of the surface 21a to be measured of the object 21 to be measured is obtained.

Therefore, according to the configuration of this embodiment, even if the rotational axis of the θ stage 10 fluctuates, the influence of the fluctuation of the axis can be removed and the shape of the surface to be measured 21a of the object to be measured 21 can be accurately determined. can be measured.

In addition, in this embodiment, various other embodiments described above may be used as needed, such as the X' stage 40 on the θ stage 10.
and the shape of the object to be measured 21.

The center of curvature of the object to be measured 21 and the θ stage 1 depending on the size.
The configuration may be such that the X' stage 40 is moved so that the center of rotation of 0 coincides with the center of rotation. In addition, the present invention can be implemented with various modifications without departing from the gist thereof.

(Effects of the Invention) As detailed above, the present invention provides various effects as described below.

In claim 1, the rotation angle signal is obtained while holding the object to be measured and rotating the θ stage about the center of curvature at the center of the surface to be measured.

Since the shape of the surface to be measured is measured by taking in the output of the optical displacement sensor and the output of the X-direction movement amount detection means, the shape of the surface to be measured is measured without the need for a complicated mechanism or optical system, and without using a prototype. The shape of the surface to be measured can be measured, and the shape can be accurately measured even if the surface to be measured is a rough surface.

Further, in a second aspect of the present invention, after the prototype is attached to the θ stage to acquire the required data, the object to be measured is attached to the θ stage and the required data is similarly acquired. After that, the shape of the surface to be measured was obtained by subtracting the data for the prototype installation from the data for the installation of the object to be measured, so even if there were fluctuations in the rotation axis of the θ stage, the data could not be affected. Can measure the shape of the measurement surface.

In addition, in claim 3, since the object to be measured is placed on the θ stage via the X' stage that moves toward the side opposite to the object to be measured, the Even if the center of curvature changes, it is possible to match the center of curvature with the center of rotation of the θ stage, and the shape of the surface to be measured of an object to be measured having an appropriate shape and size can be measured.

Furthermore, in claim 4, by rotating the object to be measured in a direction perpendicular to the rotational direction of the θ stage separately from the θ stage, the surface to be measured of the object to be measured is scanned at various scanning angles. can.

Further, in claim 5, an autofocus means is provided for moving the optical displacement sensor in a predetermined direction so that the output of the optical displacement sensor becomes a predetermined value, so that when the surface to be measured is greatly uneven, Even if the center of curvature of the object to be measured and the center of rotation of the θ stage are misaligned, the shape of the surface to be measured can always be accurately measured without causing positional deviation of the measurement point.

[Brief explanation of the drawing]

1 to 5 are aspherical shapes related to the present invention? #1
This is shown to explain one embodiment of the
The figure is an overall configuration diagram of the apparatus of the present invention, schematically showing the mechanical parts. Figure 2 is a sectional view of the holding mechanism that holds the object to be measured. Figures 3 (a) and (b) are the mechanical parts of the apparatus. A more detailed front view and a top view, FIG. 4 is a diagram explaining the relationship between changes in the surface to be measured and the light receiving position of the optical displacement sensor, and FIG. 5 is a diagram explaining the relationship between the optical displacement sensor and the movement amount detection means. FIG. 6 is a diagram of the drive mechanism of the object to be measured as another embodiment of the device of the present invention, and FIGS. Figures 9 to 11 are diagrams illustrating an example, and Figures 9 to 11 are diagrams illustrating autofocus means as another embodiment of the device of the present invention, and Figure 12 is a configuration diagram showing still another overall device of the device of the present invention. , and FIGS. 13 to 15 are explanatory diagrams for removing the variation amount of the rotation axis of the θ stage as another embodiment of the apparatus of the present invention. DESCRIPTION OF SYMBOLS 10... θ stage, 12... θ stage rotation motor, 18... Row encoder, 19... Output shaft system, 20... Holding mechanism, 21... Measured object, 21
a... Surface to be measured, 30... X stage, 31...
Optical displacement sensor, 32...X direction movement motor, 33.
...X direction movement amount detection means, 33a...X direction movement signal generator, 33b...X direction movement amount detector, 40...
- X' stage, 43... Screw body, 44... Controller, 46... Signal processing means, 60... Auto focus circuit, 70... Prototype, 71... Memory table, 72... ...Rotation axis center variation detection means, 73...
Measurement surface displacement amount acquisition means, 74...Rotation axis center fluctuation amount correction means. Applicant's representative Patent attorney Takehiko Suzue Figure 2 Figure 7 Figure 8 Figure 9\ Figure 11 Figure 12 Figure 13 Figure 14

Claims (5)

[Claims] (1) A θ stage (10) that holds the object to be measured (21) and rotates around the center of curvature at the center of the surface to be measured, and an angle detection means (18) that detects the rotation angle of this rotation stage. , an optical displacement sensor (31) that is arranged opposite to the surface to be measured of the object to be measured and detects unevenness of the surface that appears as the object to be measured rotates; an x-stage (30) that is perpendicular to the rotation axis to move the object to be measured in the radial direction when viewed from the rotation center;
Movement amount detection means (3
3) and simultaneously receiving the output of the angle detection means, the output of the optical displacement sensor, and the output of the movement amount detection means to obtain the polar coordinate value of the detection point of the optical displacement sensor to determine the shape of the surface to be measured. An aspherical surface shape measuring device characterized by comprising: a signal processing means (46) for determining the shape of an aspherical surface. (2) A θ stage that holds the prototype (70) and the object to be measured (21) separately and rotates around the reference surface of the prototype and the center of curvature at the center of the surface to be measured of the object to be measured (
10), an angle detection means (18) for detecting the rotation angle of the θ stage, and an angle detection means (18) arranged opposite to the reference surface of the prototype or the surface to be measured of the object to be measured, and adapted to the rotation of the prototype or the object to be measured. an optical displacement sensor (31) that detects unevenness that appears as a result;
an x stage that moves the optical displacement sensor in a direction perpendicular to a rotation axis facing the reference surface or the surface to be measured of the prototype;
Movement amount detection means (3
3) and obtaining the periodic fluctuation amount of the rotation axis of the θ stage from the output of the angle detection means, the output of the optical displacement sensor, and the output of the movement amount detection means when the prototype is attached to the θ stage. The measured object is detected from the output of the angle detecting means, the output of the optical displacement sensor, and the output of the movement amount detecting means when the measured object is mounted on the θ stage. Measurement surface displacement amount acquisition means (73) for acquiring the displacement amount of the measurement surface, and rotational axis fluctuation amount obtained by the rotational axis fluctuation amount detection means. An aspherical surface shape measuring device characterized by comprising: a rotation axis center fluctuation amount correcting means (74) for correcting a measurement surface displacement amount. (3) An x' stage is provided on the θ stage (10) to linearly move the prototype (70) or the object to be measured (21), so that the center of curvature of the object to be measured and the center of rotation of the θ stage are aligned. The aspherical shape measuring device according to claim 1 or 2, wherein the aspherical shape measuring device is moved. (4) The means for holding the object to be measured (21) is provided with an α stage (50) that rotates the object to be measured about a line connecting the center of curvature of the object to be measured and the center of the surface to be measured as the rotation axis. The aspherical shape measuring device according to claim 1. (5) An autofocus circuit (60) for driving and controlling the x-stage (30) to move the optical displacement sensor so that the output of the optical displacement sensor (31) becomes a predetermined value is provided. The aspherical shape measuring device according to claim 2.