JP2002250622A - Shape-measuring method and device for optical element, and its type - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simultaneously measure an edge or a mark with a noncontact optical probe, and to determine the absolute shape of an optical element by converting the measured value into coordinates determined by the edge or the like. SOLUTION: In this shape-measuring method and this device for the optical element and its type, a three-dimensional coordinate measuring means 30 for measuring the three-dimensional coordinates of the optical element which is an inspection object or its type O is used, and processing for applying measurement data acquired by the three-dimensional coordinate measuring means 30 to a function for expressing the shape is carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring the shape of an optical element and its mold, and more particularly, to measuring the absolute shape of an optical element or a mold used for manufacturing them by plastic molding, glass molding or the like. And a method and apparatus for doing so.

[0002]

2. Description of the Related Art Since the surface shape of an optical element such as a lens or a prism greatly affects the performance of an optical system, measurement of an absolute surface shape is an important issue in quality control in a manufacturing process of the element. As a method for measuring the surface shape of an optical element, an interferometer is conventionally used, but the interferometer is a relative comparison with a reference surface and cannot measure an absolute shape.

[0003] As a method of measuring the absolute shape,
A stylus-type shape measuring instrument is commercially available, but it mainly measures the shape of the cross section perpendicular to the optical axis. Since it is difficult to measure the surface shape in two dimensions, the asymmetric surface shape of the optical element is used. Cannot be measured correctly. Also, the mold had the same problem.

On the other hand, there is a three-dimensional measuring device as a device capable of measuring the three-dimensional coordinates of a sample surface with high accuracy. However, since the device generally does not have an absolute coordinate system, an absolute shape cannot be measured. There is.

Under such circumstances, the present applicant has filed Japanese Patent Application No.
In No. 230398, in order to determine the absolute shape of an optical element to be inspected, a part serving as a coordinate reference of a three-dimensional measuring machine is provided in a part of a member for holding an optical element as an object to be inspected, It is proposed to measure the surface shape of the optical element by measuring at the same time as the shape of the optical element, converting the obtained measured value into coordinates with respect to the reference, and applying the converted value to a predetermined function. In this application, it is also proposed that the coordinates of the outer periphery of the optical element or the mold are measured so as to omit providing a coordinate reference for the holder.

[0006]

Problems to be Solved by the Invention Japanese Patent Application No. Hei 11-2
In the case of No. 30398, since a contact type three-dimensional measuring machine in which the probe is brought into contact with the surface of the optical element to be measured was conceived, a coordinate reference for determining the absolute shape was provided on the holder, or the coordinates of the outer periphery of the optical element or the like were used. Is measured. This is because when the probe is brought into contact with the surface to be measured, the position of the edge of the surface cannot be measured accurately.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to provide an optical element to be inspected or a surface shape of the mold together with an edge of the surface or an edge of the surface. An object of the present invention is to provide a shape measuring method and apparatus for simultaneously measuring a provided mark with a non-contact optical probe, converting the measured value into coordinates obtained from the edge or mark position, and obtaining the absolute shape of the optical element.

[0008]

According to the present invention, there is provided an optical element and a method for measuring the shape of a mold of the present invention, which include a three-dimensional coordinate measuring means for measuring three-dimensional coordinates of an optical element or a mold of the object. A method of applying measurement data obtained by the three-dimensional coordinate measuring means to a function representing a shape.

According to another aspect of the present invention, there is provided a method of measuring the shape of an optical element or a mold thereof, the method comprising: From the data, a plurality of edges of the outer peripheral portion or the inner peripheral portion of the test object, or a plurality of optically detectable marks provided on the test object, or coordinates of a position determined based on the edge or the mark. Detect the value,
This method is characterized in that a coordinate reference position is calculated from detected coordinate values, and a process of applying the function to a function representing a shape based on the coordinate reference position is performed.

Another aspect of the present invention is a method of measuring the shape of an optical element and its mold by measuring three-dimensional coordinates obtained by a three-dimensional coordinate measuring means for measuring the three-dimensional coordinates of an optical element or its mold as a test object. This is a method characterized by determining the eccentricity of an optical element or its type from data.

In this case, it is desirable to use three-dimensional coordinate measuring means for measuring three-dimensional coordinates in a non-contact manner with the optical element or the mold as the test object.

It is desirable to use a three-dimensional coordinate measuring means for measuring three-dimensional coordinates with a non-contact optical probe for an optical element or a mold as a test object.

In the present invention, three-dimensional coordinate measuring means for measuring the three-dimensional coordinates of the optical element or the type of the test object is used, and the measurement data obtained by the three-dimensional coordinate measuring means is converted into a function representing a shape. In the process of performing the fitting process, the coordinate reference position of the surface can be calculated from the measurement data of the coordinate reference position of the optical element to be inspected, and the obtained measurement data is converted into coordinates with respect to the reference to obtain the absolute value of the optical element. The shape can be determined.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The principles and embodiments of an optical element and a method and an apparatus for measuring the shape of a mold according to the present invention will be described below with reference to the drawings.

As the three-dimensional measuring machine used in the measuring method of the present invention, a non-contact three-dimensional measuring machine of an autofocus type for measuring the position of a test object with a non-contact optical probe and a non-contact three-dimensional measuring machine of a confocal microscope type There is a measuring machine. First, these principles will be described.

FIG. 1 shows an auto-focus type non-contact three-dimensional measuring machine (for example, Japanese Patent Application Laid-Open No. 2000-146532).
FIG. 2 is a diagram schematically showing the configuration of FIG. 1. Laser light emitted from a laser 11 is incident on an objective lens 15 via mirrors 13 and 12, travels toward the focal plane of the objective lens 15 at the center of the optical axis, and The light enters the surface 1 to be measured of the specimen O, is reflected, passes through the objective lens 15, passes through the mirrors 12, 13, and 14 again, and forms an image on the optical position detecting device 17. When the focus of the objective lens 15 is not in focus on the surface 1 to be measured, the imaging position of the optical position detecting device 17 changes. Therefore, this position change is captured by the optical position detecting device 17, and the objective lens 15 is moved by the moving mechanism 16. It is moved in the focusing direction, and the measurement target surface 1 is determined by the position of the objective lens 15 at the time of focusing.
Can be measured in the Z-axis direction, and the position of the XY plane can be known from the position of the XY stage 18 on which the test object O is mounted with respect to the optical axis of the objective lens 15. In this way,
The three-dimensional shape of the measurement surface 1 of the test object O can be measured.

FIG. 2 is a view schematically showing the configuration of a non-contact three-dimensional measuring device of the confocal microscope type. Light emitted from a light source 21 irradiates a first pinhole 22 and a first pinhole 22. Is reflected by the half mirror 23, enters the objective lens 24, proceeds toward the image point position of the objective lens 24 at the center of the optical axis, enters the measurement surface 1 of the test object O, and is reflected. Then, the light passes through the objective lens 24 again, passes through the half mirror 23, is disposed at a position conjugate with the first pinhole 22, passes through the second pinhole 25, and enters the photodetector 26. When the surface 1 to be measured is not at a position conjugate with the first pinhole 22, light emitted from the first pinhole 22 cannot pass through the second pinhole 25, so that the light detector 26 does not detect light. The entire system is moved in the optical axis direction by the moving mechanism 27, and the height of the surface 1 to be measured in the Z-axis direction can be measured based on the position at which the light detector 26 detects light. The position on the XY plane can be determined from the position of the XY stage 28 on which O is mounted with respect to the optical axis of the objective lens 24. In this way, the three-dimensional shape of the measurement surface 1 of the test object O can be measured.

The light beam for detecting the position of the non-contact three-dimensional measuring machine as described above is called an optical probe 2.

By scanning the measured surface 1 of the test object O using the non-contact optical probe 2, measurement data representing the surface shape is obtained. 1 is a schematic enlarged cross-sectional view near the end of No. 1; The test object O has a measured surface 1 and a peripheral side surface 3, and a boundary surface 4 between the measured surface 1 and the side surface 3 is a rounded surface. This boundary surface 4 is not to be called an edge of the surface 1 to be measured.
The position 5 where the is rounded and connected to the boundary surface 4 can be defined as an edge 5. Specifically, a position that changes from the measured surface 1 by a predetermined minute set value (for example, 1 μm) is defined as an edge 5. The edge 5 can be easily detected by scanning the measurement surface 1 of the test object O with the optical probe 2 and measuring its three-dimensional position.

Also, the mark 6 provided at a position different from the edge 5 can be read by the optical probe 2. As the mark 6, a mark such as a crosshair having a different reflectivity or absorptance from the surface to be measured 1 or an engraved mark can be used.
These marks 6 can be read by the optical probe 2. In addition, the boundary of the object O with the frame on which the optical element is mounted, the mark provided on the frame, the outer shape of the optical element of the object O, the reflective layer provided on the surface 1 to be measured, the opening, and the like. The boundary can also be used as the mark 6.

In the present invention, for example, the reference coordinates of the test object O are obtained from the position of the edge 5 or the mark 6 measured by the optical probe 2, and the obtained measured values are converted into coordinates with respect to the reference. Then, the converted measurement data is converted into a surface shape error which is a difference from the design surface shape, and the surface shape of the optical element is measured by applying the converted data to a function representing the surface shape error. Based on the outer shape of the lens or the position of the mark, the lens surface S (x _s ,
y _s, describes an example of determining a reference origin _{O s (x s0, y s0} ) of z _s).

FIG. 4A is a perspective view, and FIG. 4A is a plan view.
As shown in the figure, XYZ is the optical probe 2 as described above.
Is the coordinate system of a non-contact three-dimensional measuring machine using_s-Y_s
-Z _sIs the coordinate system of the lens surface S that is the surface to be measured. surface
Shape S (x_s, Y_s, Z_s) Reference coordinates to define
System X_s-Y_s-Z_sOrigin O_s(X_s0, Y_s0Ask for)
In this case, as shown in FIG. 4, a point A on the X and Y axes of the measuring machine
(X_a, Y_a, Z_a), B (x_b, Y_b, Z_b), C
(X_c, Y_c, Z_c), D (x_d, Y_d, Z_d) 4 points
Is measured by the optical probe 2. All four points are above
This is a point on the edge 5 described above. From the measured coordinate values, x_s0= (X_b-X_a) / 2, y_s0= (Y_d-Y_c) / 2 ... (1) as the reference origin O_s(X_s0, Y_s0) Is required, light
The measured value of the lens surface S obtained using the lobe 2 is used as the basis.
Converted to values for quasi-coordinates and the converted measurement data
Is converted to a surface shape error that is the difference from the design surface shape,
By fitting to a function representing the shape error,
The surface shape S is measured.

Also, without being limited to the points on the coordinate axes of the measuring machine, assuming that the edge 5 of the lens surface S is a circle, a plurality of points on an arbitrary edge 5 are measured, and the equation of the circle is expressed as x seeking f, and g by ^{2 + y 2 + 2fx + 2gy} + h = 0 ··· (2) using the method of least squares to fit the measured value _{(fitting), x s0 = -f, y} s0 = -g · .. (3), the reference origin O _s (x _s0 , y _s0 ) may be obtained.

In the above description, the reference origin O _s (x _s0 , y _s0 ) is obtained by using a point on the edge 5 of the lens surface S, but the mark 6 (see FIG. When the position of 3) is detected and the reference origin O _s (x _s0 , y _s0 ) is obtained, it can be calculated in the same manner as above.

If the measured data representing the surface shape is not converted into a value with respect to the correct reference coordinates as described above, or if it is applied to a predetermined function while having an error with respect to the reference coordinates, the surface to be measured is obtained. Even if S has a surface shape as designed, it is determined that there is an error in the surface shape, or when the measured surface S is, for example, a rotationally symmetric aspherical surface,
A coma aberration component appears in the error function, and it is impossible to determine whether the coma aberration component of the measured surface is due to a deviation of the reference coordinates, and the coma aberration component cannot be measured accurately. Therefore, in the case of measuring the shape of an optical element and its mold, the surface to be measured S
It is extremely important to determine the reference origin of the.

Next, an example of measuring the eccentricity of the lens surface S will be described.
explain. As shown in FIG.
Y of the round surface S_sShaft eccentricity α_yIf you want to
Coordinate system XY- of non-contact 3D measuring machine using lobe 2
Z and the coordinate system X of the lens surface S that is the surface to be measured_s-Y_s−
Z_sOne coordinate axis X and X_sAre matched, and in FIG.
Thus, for example, point A (x_a, Y_a, Z_a), B (x_b, Y
_b, Z_b), X_a= X _bIs measured. The place for this eccentricity measurement
In this case, the points A and B are selected on the edge 5 above,
A point within a certain minute distance from the edge 5, or
Is, if the lens surface S is a rotationally symmetric aspherical surface, the surface shape S (x
_s, Y_s, Z_s) / Sx_s= ∂S / ∂y
_s= ∂S / ∂z_s= Const. Select points that become
You. Here, the point on the edge 5 is not used in the eccentricity measurement.
The reason is that the edge 5 has the surface shape S (x_s, Y_s, Z_s)
This is because they are not always sufficiently reflected. Also,
When using the optical probe 6, the mark 6 is used with the optical probe 2.
And the coordinate value is measured in the same manner. As above
From the coordinate values of points A and B measured by_y= Arctan ｛(z_a-Z_b) / (Y_a-Y_b)｝ (4) Some pairs measured in this way
Ra α_yAnd calculate the average value as true α_yYou may decide
No. α_xThe same is true for

Next, FIG. 6 shows a basic configuration of an apparatus for obtaining the two-dimensional absolute shape of the optical element O to be measured by using the non-contact three-dimensional measuring device using the optical probe 2 as described above. This device uses the optical probe 2 as described above in a non-contact
A three-dimensional measuring machine 30 for measuring dimensional coordinates, and optical elements to be measured O such as lenses, aspheric lenses, mirrors, and aspheric mirrors
And a data processing unit 31 for obtaining a shape from measurement data.

FIG. 7 is a flowchart showing a procedure for measuring the shape of the surface 1 to be measured of the optical element O to be measured by the apparatus having the structure shown in FIG. First, in step 41, as shown in FIG. 4, the position of the edge 5 or the mark 6 of the optical element O to be detected is detected using the optical probe 2, and the next step 4
In step 2, the reference coordinate position of the test optical element O is detected based on, for example, equation (1).

Before, after, or simultaneously with step 41, in step 43, the surface of the measured surface 1 of the optical element 2 to be measured is moved while the optical probe 2 is moved along the surface 1 to be measured of the optical element O to be measured. Measure the shape.

Further, before, after or at the same time as steps 41 and 43, at step 44, as shown in FIG. The position of a point or the like that has entered inside is detected, and the next step 45
Then, the amount of eccentricity of the measured surface 1 of the optical element O to be measured is calculated based on, for example, Expression (4).

In step 46, the measured surface 1 of the optical element 2 to be measured obtained in step 43 is determined with respect to the reference coordinate position obtained in steps 41 and 42 while taking into account the eccentricity obtained in steps 44 and 45. Is converted. The surface shape data thus obtained may be a surface shape as it is as a point sequence, or may be a surface shape by applying a point sequence to a certain function.
Such functions include polynomials, freeform polynomials, anamorphic polynomials, power series, Zernike polynomials,
There are spline functions, interpolation of point sequences, and the like.

The measurement data thus obtained is converted into a difference from the design surface shape, that is, a surface shape error. In step 47, fitting to a function representing a surface shape error is performed. As the function, for example, a Zernike polynomial may be used. In other cases, a spline function, or interpolation of a polynomial or point sequence data may be used. . Here, the reason why the function is applied to the function by taking an error from the design surface shape instead of the measurement data itself is to make it easier to cope with the wavefront aberration component of the interference measurement.

Then, in step 48, a fitting error (fitting error), which is an error resulting from fitting the function to the surface shape error data, is confirmed.

Finally, in step 49, the absolute surface shape is evaluated from the above results.

The above method is not limited to the optical element O to be inspected.
Applicable to that type.

The eccentricity between both surfaces of the lens can be measured by using the measurement of the amount of eccentricity of the lens surface as described with reference to FIG. The embodiment will be described.

FIG. 8 shows a test lens L having such a shape that the outer peripheral center axis of the test lens L can be held with good reproducibility by holding the peripheral surface of the test lens L at three points. FIG. 9 is a diagram for explaining a method of measuring eccentricity between both surfaces in the case, and such a test lens L is held by a three-point holder 51 as shown in FIG. After holding the test lens L with the three-point holder 51, one surface 1A of the test lens L is directed to the non-contact three-dimensional measuring machine as shown in FIG. The eccentricity of the surface 1A is measured according to such a principle, and then, while the non-contact three-dimensional measuring machine is fixed, FIG.
As shown in FIG. 8B, the lens L to be inspected is rotated together with the three-point holder 51 in an arrangement rotated by 180 ° in the plane of FIG. 8B, and the other surface 1B of the lens to be inspected L is non-contact three-dimensionally. The eccentricity of the surface 1B is measured in the same manner toward the measuring machine. Surface 1A
By determining the difference between the inclinations of the axes of the respective surfaces 1A and 1B in consideration of the positional relationship between the respective surfaces 1A and 1B when measuring the respective surfaces 1B, the eccentricity between the surfaces of the test lens L can be obtained.

FIG. 9 shows that the peripheral surface of the lens L to be inspected is held at three points, so that the central axis of the outer diameter of the lens L to be inspected is difficult to hold with good reproducibility. 9 is a diagram for explaining a method of measuring the eccentricity between the two surfaces in the case where the method of measuring the eccentricity between the surfaces in FIG. 8 is performed with high accuracy. In this case, the holder 52 holding the lens L to be measured is attached to the shaft 53. A mechanism is provided to enable accurate 180 ° rotation around the. During the rotation, the holder 52 is moved to the stage 1.
8 (28) and the objective lens 1 of the non-contact three-dimensional measuring machine 30
The holder 52 may be provided sufficiently above the stage 18 (28) so as not to interfere with the stage 5 (24), and the objective lens 15 (24) may be retracted upward while the holder 52 is rotating. Then, in the same manner as in the case of FIG. 8, the eccentricity of the surface 1A and the surface 1B is measured, and the difference between the inclinations of the axes of the surfaces 1A and 1B is obtained, thereby obtaining the eccentricity between the surfaces of the lens L to be measured. Can be.

FIG. 10 is a view for explaining a method of measuring the eccentricity between the two surfaces when the eccentricity between the surfaces of the lens L to be inspected is performed with higher accuracy. In this case, the holder 52 is fixed and the test is performed. While holding the lens L in the air, the two non-contact three-dimensional measuring machines 30 and 30 ′ arranged on both sides of the lens L respectively face the objective lens 15 with respect to each of the surfaces 1 A and 1 B of the test lens L
What is necessary is just to scan (24).

Next, an example of a method of measuring a positional shift between lenses of an optical system including a plurality of lenses using a non-contact three-dimensional measuring device using the above-described optical probe 2 will be described. As shown in FIG. 11A, the side surface of the test object (optical system) O including the lenses L1 to L3 is scanned by the optical probe 2 in two different directions A and B along the optical axis, and each lens L1 is scanned.
When the side surface positions of L3 are determined, a measurement signal as shown in FIG. 11B is obtained. In FIG. 11B, a solid line indicates a side position when scanning is performed in the direction A, and a broken line indicates a direction B.
2 shows the side position when scanning is performed. With reference to the lens L1, it can be seen that the lens L2 is displaced by d toward the scanning position B side, has a misalignment of d / 2, and the lens L3 has relatively no misalignment.

Next, FIG. 12 shows an example of measuring the mutual positional deviation of two prisms P1 and P2 each having, for example, a free-form surface, and the positional deviation between the surfaces of the prisms P1 and P2. In this case, as shown in FIG. 12A, the edges of the side surfaces (outer peripheral surfaces) of the prisms P1 and P2 are detected by the optical probe 2 and applied to design values, thereby obtaining the results shown in FIG. 12B. In this way, the local coordinates of each effective surface intersecting the side surface are calculated. Then, by calculating the relative position between the local coordinates, the positional deviation between the effective surfaces of the prisms P1 and P2 can be measured. Further, the relative position between the prism P1 and the prism P2 can be measured. Each prism may be provided with positioning marks, unevenness, holes, lines, and the like.

Next, using a white interferometer, a micro-interferometer, or an interferometer, the fine irregularities, undulations, and roughness of the surface to be measured of a test optical element such as a deformable mirror (variable mirror) are measured. An example will be described. As shown schematically in FIG. 13, the white light interferometer is configured such that light emitted from a light source 61 that emits short-coherence light such as a halogen lamp, an LED, and a superluminescent diode is reflected by a half mirror 62. Incident on the objective lens 63,
Proceeding toward the image point position of the objective lens 63, a part of the light is reflected by the half mirror 64 disposed therebetween, and reflected by the central mirror 65 disposed at the center of the exit side surface of the objective lens 63, The reflected light is reflected again by the half mirror 64 and returns to the objective lens 63. Objective lens 6
Of the light that has entered the half mirror 64 from 3, the light that has passed through the half mirror 64 is incident on the measurement surface 1 of the test object O, is reflected, enters the half mirror 64 again, and transmits it. The light reflected by the center mirror 65 of the objective lens 63, reflected by the half mirror 64, and returned to the objective lens 63, and the measurement surface 1 of the test object O transmitted through the half mirror 64
Is reflected by the half mirror 64 and passes through the objective lens 63.
Is returned by the objective lens 63, passes through the half mirror 62, and enters the photodetector 66. Only when the distance from the half mirror 64 to the center mirror 65 is equal to the distance from the half mirror 64 to the surface 1 to be measured,
Since the two lights interfere with each other and strengthen each other, the interference signal is detected by the photodetector 66 and the objective lens 6 is detected based on the detected signal.
3. The entirety of the center mirror 65 and the half mirror 64 is moved in the optical axis direction by the moving mechanism 67, and the height of the measured surface 1 in the Z-axis direction can be measured at the position where the detection signal becomes maximum.

Therefore, it is possible to measure the fine unevenness, undulation, and roughness of the measurement surface 1 of the optical element O to be measured such as a deformable mirror using such a white interferometer. Non-contact measurement with a deformable mirror or the like is possible even using a microscopic interferometer or a normal interferometer (Fizeau type or the like). In addition, it is convenient to perform a shape measurement using an interferometer if a reflection coat is applied to the part of the reflecting surface of the deformable mirror, through which the light beam does not pass, or to the frame of the reference deformable mirror. is there. This is because the reflection coat outside those effective light beams serves as a reference surface, and the deformation amount of the mirror can be easily understood by measuring the shape of the deformable mirror with respect to the reference surface.

Here, an example of the variable mirror will be described. The deformable mirror is also called a deformable mirror, and FIG. 14 is a diagram showing a configuration of an example of this deformable mirror, and is a diagram relating to an electrostatically driven deformable mirror 302. The deformable mirror 302 is driven by an electrostatic force, and a reflective film 303 serving also as an electrode is provided on a deformable plate 304 made of an organic material.
Several divided electrodes 307 are provided on the substrate 306 separated by the spacer 305, and the reflective film 303 can be deformed into a desired shape by adjusting the variable resistor 308. When the reflective film 303 is provided also in the portion 302B adjacent to the spacer 305 that does not deform, it is convenient when performing interference measurement or shape measurement of the reflective film 303 by the Shack-Hartmann method or the like. This undeformed part 3
It is not necessary to provide the reflective film 303 on 02B.

FIG. 15 shows the deformable mirror 302 of FIG.
Is a view from above, and the inside of an octagon is a reflection film 303.
It is the part to be deformed. The outer cross mark is a positioning mark provided on the reflective film 303, the deformable plate 304, the spacer 305, the substrate 306, or the like by a method such as lithography, printing, or cutting. The positioning mark of the cross mark is formed by the deformable mirror 302.
When the camera is incorporated into a digital camera, a TV camera, an endoscope, or the like, it is used for assembling the deformable mirror 302 by approaching a designed position. This positioning mark is convenient for high-precision assembly.

The shape of such a variable mirror can be measured by using the Shack-Hartmann method.
Before explaining the example, the Shack-Hartmann method will be briefly described. The Shack-Hartmann method is a representative example of a wavefront measurement sensor (Matsuo Tsuruta, "4th Pencil of Light-Applied Optics for Optical Engineers", pp. 209-210 (1997).
"The Review of LaserEngineering" Vol. 27, No. 2,
pp.78-83), which makes it possible to measure the Hartmann aberration measurement method, which has been known for a long time, in real time. As shown in FIG.
The wavefront 71 incident on the microlens array 70
Is divided into small zones, and the average traveling direction of a thin light beam incident on each microlens of the microlens array 70 is detected by a two-dimensional sensor placed on the focal plane 72 of the microlens array 70. Output the data of two orthogonal components indicating the directions of the light rays, and calculate the wavefront from a total of 2N (N is the number of microlenses) light ray data. FIG. 16A shows a case where the wavefront 71 is a plane wave, and FIG. 16B shows a case where the wavefront 71 is deformed. The direction of each light beam incident on the focal plane 72 is equivalent to the deformation of the wavefront 71. Is a plane wave (in the direction of the broken line; FIG. 16)
(A)).

FIG. 17 is a diagram showing an example in which the shape of the variable mirror 302 as shown in FIG. 14 is measured using the Shack-Hartmann method. According to the Shack-Hartmann method described above, there is an advantage that measurement can be performed even with a variable mirror 302 having a large deformation that cannot be measured by interference measurement.

In FIG. 17, the xenon lamp 310 is driven by a power supply 311 and
The light from 10 passes through the lens 312 to the light guide 31.
3 and further narrowed down by a pinhole 314. The light exiting from the pinhole 314 is converted into parallel light through a lens group 315, the direction is changed by a half mirror 316, and the light enters the variable mirror 302, which is a test object, from the front. The light reflected by the variable mirror 302 passes through a half mirror 316, the thickness of the light beam is changed by an afocal variable power optical system 317, and the wavefront is divided into a plurality of zones by a microlens array 318 in the Shack-Hartmann method. Corresponding to the number of converging points, and forms an image on the solid-state imaging device 319. The output from the solid-state imaging device 319 is digitized by the signal processing circuit 320 and is output to the computer 32.
1 and the reflection film 303 of the variable mirror 302
Is obtained.

Here, the afocal variable magnification optical system 317
Is an optical system for changing the magnification so that the imaging area of the solid-state imaging device 319 can be fully utilized when the size or the like of the variable mirror 302 as a test object changes. Lens group 31
Similarly, reference numeral 5 denotes a variable power optical system for enabling the light emitted from the pinhole 314 to cover the size of the variable mirror 302. The light guide 313 may be an optical fiber bundle or a single optical fiber. In the latter case, the pinhole 314 becomes unnecessary.

In addition to the electrostatically driven variable mirror 302, the measuring apparatus shown in FIG. 17 can also measure an electromagnetically driven variable mirror, a variable mirror using a piezoelectric effect, or a variable focus lens having a variable surface shape.

FIG. 18 is a view showing an example of a variable focus lens, in which the shape of a variable focus lens 334 whose deformable thin film 333 changes its shape when a fluid 332 is taken in and out is shown. In the figure, 3
Reference numeral 35 denotes a transparent substrate, and 336, a pump for taking in and out the fluid 332. If a micropump or the like made by a micromachine technique is used as the pump 336, the varifocal lens 334 may be reduced in size.

When measuring the shape of the variable mirror 302 with the Shack-Hartmann measuring apparatus shown in FIG. 17, it is desirable to also measure the flat portion 302B around the variable mirror 302 that does not change its shape. Then, the variable mirror 30
The shape of the reflective film 303 can be measured, including the eccentricity of the deformed portion of the reflective film 303 with respect to the shape around 2, and the reference coordinates of the variable mirror 302 as the test object.

For example, as shown in FIG. 19, the periphery of the microlens array 323 is a transmission plane, and the shape of the plane portion 324 that does not change the shape of the periphery of the variable mirror 302 is directly reflected in the imaging area of the solid-state imaging device 319. By doing so, the eccentricity of the deformable portion of the reflective film 303 can be measured more accurately. Alternatively, the reference coordinates of the variable mirror 302 can be accurately measured.

Alternatively, the shape of the microlens array 326 used in place of the microlens array 323 is shown in FIG.
As shown in the figure, the focal length is reduced only in the peripheral portion, and the outer edge 327 of the variable mirror 302 and the solid-state image sensor 319
The edge 32 is made conjugate with the imaging surface of
7 may be imaged on the imaging surface of the solid-state imaging device 319 to measure the eccentricity of the deformable portion of the reflective film 303. Alternatively, the reference coordinates of the variable mirror 302 may be measured.

19 and 20 have the merit that the shape and the eccentricity or the reference coordinates can be measured at the same time. The peripheral portion 30 of the variable mirror 302 that is not deformed
The reflective film 303 may not be provided on 2B.

FIG. 21 shows laser length measuring devices 350 and 351.
FIG. 9 is a diagram for explaining a method of measuring the surface shape of the variable mirror 302 using the method. The laser length measuring device 350 measures the deformed portion of the reflective film 303, and the laser length measuring device 351 measures the non-deformed portion 352 of the reflective film 303, and obtains a difference between the measured values to obtain a deformed portion of the reflective film 303. Can be measured based on the peripheral portion. Here, laser measuring device 3
Both 50 and 351 may not be provided, and each part of the reflective film 303 and its undeformed part 352 may be separately measured twice. In addition, the laser length measuring device 350, 3
Reference numeral 51 denotes a device for measuring the distance to the reflection point of the laser light by measuring the distance that the laser light reciprocates.

Here, specific examples of the optical element to be measured O to be measured according to the present invention include a normal axisymmetric spherical lens,
There are aspherical lenses, double-sided aspherical lenses, and lens systems combining them. Also, prisms that constitute catadioptric optical systems, free-form surface prisms whose one of the surfaces is a rotationally asymmetric surface such as a free-form surface, deformation It is also possible to measure the surface shape, displacement, eccentricity, and the like of possible deformable mirrors, deformable lenses, and deformable prisms. Furthermore, it is possible to measure the surface shape, positional deviation, eccentricity, and the like of a device in which these optical elements are integrally attached to a frame or a unitized device. The deformable lens includes a lens made of an elastically deformable material such as synthetic rubber, a soft contact lens, and a variable focus lens. Note that the deformable mirror includes a type driven by electrostatic force, a type driven by electromagnetic force, and a type that changes its shape using a piezoelectric material, an electrostrictive material, or a magnetostrictive material. They can also be measured individually, in intermediate products, or in assembled final products.

Of course, the measuring method and measuring apparatus of the present invention can be used not only for measuring optical elements such as lenses and prisms, but also for measuring a mold for integrally molding the optical elements.

As a non-contact three-dimensional measuring device for measuring the surface shape, position, etc. of the optical element to be tested or its mold, those using an optical probe as described with reference to FIGS. 17, the Shack-Hartmann method measuring apparatus described with reference to FIG. 20 and the laser length measuring apparatus described with reference to FIG. 21 can be used as well as those using ultrasonic waves.

The method and apparatus for measuring the shape of the optical element and its mold according to the present invention described above can be constituted, for example, as follows.

[1] Using three-dimensional coordinate measuring means for measuring the three-dimensional coordinates of the optical element or the type of the test object,
An optical element and a method and apparatus for measuring the shape of an optical element, wherein the processing is performed by applying measurement data obtained by the three-dimensional coordinate measuring means to a function representing a shape.

[2] From the measurement data of the three-dimensional coordinates obtained by the three-dimensional coordinate measuring means for measuring the three-dimensional coordinates of the optical element or the type of the test object, a plurality of outer peripheral portions or inner peripheral portions of the test object are obtained. Of the edge, or a plurality of optically detectable marks provided on the test object, or a coordinate value of a position determined based on the edge or the mark is detected, and a coordinate reference position is determined from the detected coordinate value. And calculating the shape of the optical element based on the coordinate reference position and applying the function to a function representing the shape.

[3] Obtaining the eccentricity of the optical element or its type from the measurement data of the three-dimensional coordinates obtained by the three-dimensional coordinate measuring means for measuring the three-dimensional coordinates of the optical element or its type as the test object. Characteristic optical element and method and apparatus for measuring shape of mold.

[4] The optical device as described in any one of [1] to [3] above, wherein a three-dimensional coordinate measuring means for measuring three-dimensional coordinates in a non-contact manner with the optical element or the mold as a test object is used. Method and apparatus for measuring shape of element and its mold.

[5] The method as described in any one of [1] to [3] above, wherein a three-dimensional coordinate measuring means for measuring three-dimensional coordinates with a non-contact optical probe is used for the optical element or the mold as a test object. And a method and apparatus for measuring the shape of the optical element.

[6] The three-dimensional coordinate measuring means for measuring three-dimensional coordinates in a non-contact manner is used for an optical element or a mold as a test object made of an elastically deformable material. A method and an apparatus for measuring the shape of the optical element and its mold according to any one of the preceding claims.

[7] The method according to the above-mentioned item 1, wherein a three-dimensional coordinate measuring means for measuring three-dimensional coordinates with a non-contact optical probe is used for an optical element or a mold as an object made of an elastically deformable material. 4. An optical element according to claim 3, and a method and an apparatus for measuring the shape of the mold.

[8] The optical element according to any one of the above items 1 to 7, wherein the optical element or the type of the test object is an aspherical lens or the type, and the shape measuring method of the type and the type. apparatus.

[0069]

[9] The optical element as described in 1 above, wherein the optical element or the mold thereof has a free-form surface.
8. An optical element according to any one of claims 1 to 7, and a method and an apparatus for measuring a shape of the optical element.

[10] The optical element and the method and apparatus for measuring the shape of the optical element according to any one of the above items 1 to 7, wherein the optical element to be inspected is a variable mirror.

[11] The optical element according to any one of the above items 1 to 7, wherein the optical element or the type of the test object is a double-sided aspherical lens or the type thereof, and the shape measuring method of the type. And equipment.

[12] The optical element and the method and apparatus for measuring the shape of the optical element according to any one of the above items 1 to 7, wherein the optical element to be inspected is a lens integrally attached to the frame. .

[13] The above-mentioned 1 characterized in that the optical element as a test object is a lens assembled in a unit.
8. An optical element according to any one of claims 1 to 7, and a method and an apparatus for measuring a shape of the optical element.

[14] The method for measuring the shape of an optical element and its mold according to any one of the above items 1 to 13, wherein an optical element as an object or a mold thereof is provided with an optically detectable mark. And equipment.

[15] The optical system according to the above item 1 or 2, wherein any one of a polynomial, a free-form surface polynomial, an anamorphic polynomial, a power series, a Zernike polynomial, and a spline function is used as a function representing the surface shape. Method and apparatus for measuring shape of element and its mold.

[16] A surface shape measuring apparatus using the optical element and the shape measuring method of the mold according to any one of the above items 1 to 15.

[17] The inter-plane eccentricity of the plurality of surfaces is obtained from the measurement data of the three-dimensional coordinates obtained by the three-dimensional coordinate measurement means of the plurality of surfaces of the optical element having the plurality of optical surfaces. Method and apparatus for measuring shape of optical element and its mold.

[18] The method and apparatus for measuring the shape of an optical element and a mold thereof according to the above item 17, wherein a rotating jig for rotating the optical element having a plurality of surfaces by a predetermined angle while holding the optical element is used.

[19] The method and apparatus for measuring the shape of an optical element and its mold according to the above item 17, wherein the three-dimensional coordinates of the plurality of surfaces are measured while holding the optical element having a plurality of surfaces.

[20] The mutual position of the optical element or its type is determined from the measurement data of the three-dimensional coordinates obtained by the three-dimensional coordinate measuring means for measuring the three-dimensional coordinates of the optical element or its type as the test object. An optical element and a method and an apparatus for measuring the shape of a mold thereof.

[21] From the measured data of the three-dimensional coordinates obtained by the three-dimensional coordinate measuring means, the coordinate values of a plurality of edges of the outer peripheral portion or the inner peripheral portion of each test object are detected, and from the detected coordinate values. 21. The method and apparatus for measuring the shape of an optical element and its mold according to the above item 20, wherein the mutual position between the test objects is calculated.

[22] The optical system according to the above item 21, wherein the local coordinates are calculated for each surface constituting each test object when calculating the mutual position between the test objects from the coordinate values of each edge. Method and apparatus for measuring shape of element and its mold.

[23] A non-contact optical probe is incident from a direction substantially perpendicular to the optical axis of the optical element or its type as a test object, and the non-contact optical probe is scanned substantially parallel to the optical axis. 23. A method and an apparatus for measuring a shape of an optical element and a mold thereof according to any one of the above items 20 to 22, wherein:

[24] The non-contact optical probe is scanned in at least two different directions.
4. The method and apparatus for measuring the shape of the optical element and the mold according to 3.

[25] The optical element and the method and apparatus for measuring the shape of the optical element according to any one of [20] to [24], wherein the test object comprises a plurality of lenses.

[26] The optical element according to any one of the above items 20 to 25, wherein the test object is an optical element having a surface formed of a free-form surface or a mold thereof, and a method for measuring the shape of the optical element. apparatus.

[27] An optical element characterized by measuring at least one of the shape, undulation, and roughness of a flat or concave or convex surface of an optical element as a test object or its mold using a white light interferometer. A method and apparatus for measuring the shape of the mold.

[28] Measurement of the shape of an optical element and its mold characterized by measuring at least one of the unevenness, undulation and roughness of the surface of the optical element or its mold as a test object using a microinterferometer Methods and apparatus.

[29] An optical element and a method of measuring the shape of the mold, characterized by measuring at least one of the unevenness, undulation, and roughness of the surface of the optical element or the mold as an object using an interferometer And equipment.

[30] Any one of the above items 27 to 29, wherein the optical element to be inspected is a variable mirror.
Item 7. A method and an apparatus for measuring a shape of an optical element and a mold thereof according to the above.

[31] The optical element according to any one of the above items 27 to 29, wherein the optical element as a test object is an optical element made of an elastically deformable material, and a method for measuring the shape of the optical element. apparatus.

[32] An optical element and a method and apparatus for measuring the shape of an optical element characterized by measuring the surface shape of an optical element whose surface shape changes using the Shack-Hartmann method.

[33] An optical element and a method and apparatus for measuring the shape of an optical element characterized by measuring the surface shape of a variable mirror using the Shack-Hartmann method.

[34] An optical element and a method and apparatus for measuring the shape of an optical element characterized by measuring the surface shape of an optical element whose surface shape changes using the Shack-Hartmann method, together with the eccentricity with respect to the outer shape.

[35] A method for measuring the shape of an optical element whose shape changes, together with the eccentricity with respect to the outer shape, using the Shack-Hartmann method having a microlens array, and a method of measuring the shape of the optical element. apparatus.

[36] By using the Shack-Hartmann method having a microlens array to make the focal length at the periphery of the microlens array different from the focal length at the center, the surface shape of the optical element changes. And an optical element and a method and apparatus for measuring the shape of the mold.

[37] The optical element and the method and apparatus for measuring the shape of the optical element according to the above item 36, wherein the test object is a variable mirror whose shape changes.

[38] An optical element characterized by measuring the deformation of a variable mirror using a laser length measuring device, and a method and an apparatus for measuring the shape of the optical element.

[39] Both the undeformed peripheral portion and the deformable portion of the variable mirror are measured using a laser length measuring device, and the displacement of the deformable portion relative to the peripheral portion of the variable mirror is measured. Method and apparatus for measuring shape of optical element and its mold.

[0100]

As is apparent from the above description, according to the method and apparatus for measuring the shape of the optical element and its mold according to the present invention, the coordinate reference of the surface of the optical element as the test object is obtained from the measurement data of the surface. The position can be calculated, and the obtained measurement data can be converted into coordinates with respect to the reference to accurately determine the absolute shape of the optical element.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a configuration of an auto-focus type non-contact three-dimensional measuring machine usable in the present invention.

FIG. 2 is a diagram schematically showing a configuration of a non-contact three-dimensional measuring device of a confocal microscope type usable in the present invention.

FIG. 3 is a schematic enlarged cross-sectional view of the vicinity of an end of a measurement surface of a test object.

FIG. 4 is a diagram for explaining a method of obtaining a reference origin of a surface to be measured by a non-contact three-dimensional measuring machine using an optical probe.

FIG. 5 is a diagram for explaining how to determine the eccentricity of the surface to be measured by a non-contact three-dimensional measuring machine using an optical probe.

FIG. 6 is a diagram showing a basic configuration of an apparatus for obtaining a two-dimensional absolute shape of a test optical element using a non-contact three-dimensional measuring device using an optical probe.

FIG. 7 is a diagram showing a flow of a procedure when measuring a shape of a surface to be measured of a test optical element.

FIG. 8 is a diagram for explaining a method of measuring eccentricity between both surfaces of a test lens.

FIG. 9 is a diagram for explaining another method of measuring the eccentricity between both surfaces of a test lens.

FIG. 10 is a view for explaining still another method of measuring the eccentricity between both surfaces of a test lens.

FIG. 11 is a diagram for explaining an example of a method for measuring a positional shift between lenses of an optical system including a plurality of lenses using a non-contact three-dimensional measuring device using an optical probe.

FIG. 12 is a diagram for describing an example of measuring a mutual positional deviation of two prisms each having a free-form surface and a positional deviation between surfaces of each prism.

FIG. 13 is a diagram schematically showing a configuration of a white light interferometer usable in the present invention.

FIG. 14 is a diagram illustrating a configuration of an example of a variable mirror.

15 is a view of the variable mirror of FIG. 14 as viewed from above.

FIG. 16 is a diagram for explaining the Shack-Hartmann method that can be used in the present invention.

FIG. 17 is a diagram showing an example in which the shape of a variable mirror is measured using the Shack-Hartmann method.

FIG. 18 is a diagram illustrating a configuration of an example of a variable focus lens.

FIG. 19 is a diagram showing a modification of FIG. 17;

FIG. 20 is a diagram showing a configuration of a microlens array for a modification of FIG. 17;

FIG. 21 is a diagram for explaining a method of measuring the surface shape of a variable mirror using a laser length measuring device.

[Explanation of symbols]

 O: Test object S: Lens surface (measurement surface) L: Test lens L1, L2, L3: Lens P1, P2: Prism 1: Measurement surface 2: Optical probe 3: Side surface 4: Boundary surface 5: Edge 6 Mark 11 Laser 12 13, 14 Mirror 15 Objective Lens 16 Moving Mechanism 17 Optical Position Detector 18 XY Stage 21 Light Source 22 First Pinhole 23 Half Mirror 24 Objective Lens 25 Second pinhole 26 Photodetector 27 Moving mechanism 28 XY stage 30, 30 'Non-contact three-dimensional measuring machine 31 Data processing unit 41-49 Procedure 51 ... Three-point holder 52 ... Holder 53 ... Axis 61 Light source 62 Half mirror 63 Objective lens 64 Half mirror 65 Central mirror 66 Photodetector 67 Moving mechanism 70 Microlens array 71 Wavefront 72 Focus Point surface 302: deformable mirror 302B: undeformed portion (flat portion) 303: reflective film 304: deformable plate 305: spacer 306: substrate 307: split electrode 308: variable resistor 310: xenon lamp 311: power supply 312: lens Reference numeral 313: light guide 314: pinhole 315: lens group 316: half mirror 317: variable power optical system 318: micro lens array 319: solid-state image sensor 320: signal processing circuit 321: computer 323: micro lens array 324: plane portion 326 ... Microlens array 332. Fluid 333. Thin film 334... Variable focus lens 335. Transparent substrate 336. Pump 327.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masato Anagaki 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside Olympus Optical Industrial Co., Ltd. (72) Kimihiko Nishioka 2-43-2 Hatagaya, Shibuya-ku, Tokyo F-term (reference) in Olympus Optical Co., Ltd. GG04 GG07 GG11 GG62 NN05 NN17 NN18 NN19 NN26

Claims (3)

[Claims] 1. An optical element to be inspected or its type 3
Using three-dimensional coordinate measuring means for measuring three-dimensional coordinates,
An optical element and a method for measuring the shape of an optical element, characterized by performing a process of applying measurement data obtained by a dimensional coordinate measuring means to a function representing a shape. 2. An optical element to be inspected or its type 3
From the measurement data of the three-dimensional coordinates obtained by the three-dimensional coordinate measuring means for measuring the three-dimensional coordinates, a plurality of edges of the outer peripheral portion or the inner peripheral portion of the test object or optically detectable provided on the test object can be detected. A process of detecting coordinate values of a plurality of marks or a position determined based on the edges or marks, calculating a coordinate reference position from the detected coordinate values, and applying the calculated coordinate reference position to a function representing a shape based on the coordinate reference position. And a method for measuring the shape of the optical element. 3. An optical element to be inspected or its type 3
An optical element and a shape measuring method of the mold, wherein the eccentricity of the optical element or its type is obtained from the measurement data of the three-dimensional coordinates obtained by the three-dimensional coordinate measuring means for measuring the three-dimensional coordinates.