JPH074929A - Measuring apparatus of face shape - Google Patents

Abstract

PURPOSE:To measure a face shape quickly and precisely by providing the apparatus with a displacement-amount detection means which detects the relative displacement amount of a probe, an angle detection means which detects the angle of rotation of a rotating scanning operation and a latch means which latches detected data by the displacement-amount detection means. CONSTITUTION:A swiveling shaft 21 is constant-speed-driven at a speed V0 by the instruction of a control computer, and the edge line of an object 30 to be measured is scanned at a definite speed by an optical probe for an autofocus microscope 20. At this time, a measured swiveling angle theta0 is output, and it is input to A of a comparator 68. In addition, the output of a swiveling-angle detector 57 is input to B of the comparator 68. When the measured swiveling angle theta0 which has been set at this time coincides with the present value of the swiveling angle theta0, an A=B signal is output from the comparator 68. In addition, by the A=B signal, a focused-state signal as the output of a focused-state detector 50, a fine-adjustment slide movement amount as the output of a fine-adjustment movement-amount detector 53 and an angle of inclination as the output of an angle-of-inclination detector 51 are latched by latches 65, 66, 67, they are sent to a computer, and data on one cross section of the object 30 to be measured is acquired.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface profile measuring apparatus, and more particularly to a surface profile measuring apparatus for measuring an aspherical surface such as an aspherical lens at high speed and with high accuracy.

In particular, the present invention is suitable for projecting an optical probe or the like onto a surface to be measured and measuring the shape of the surface to be measured based on the state of projection of reflected light from the surface onto the detection sensor. .

[0003]

2. Description of the Related Art Conventionally, as a method of measuring the surface shape of an aspherical lens or the like, an object to be measured is moved in an XY coordinate system, the surface of the object to be measured is scanned by a contact probe, and the amount of movement of the probe measures the object. The direction of finding the shape of an object is generally used. On the other hand, as a surface shape measuring method using a non-contact type probe, there are JP-A-61-1907 and JP-A-61-1.
As disclosed in Japanese Patent No. 7908, a focusing state determination optical system and a moving means for focusing the optical system on a surface to be measured of the object to be measured are provided, and the surface shape of the object to be measured is determined from the amount of movement of the moving means. There is a way to measure.

[0004]

In such an apparatus, it is required to accurately obtain both the position to be scanned and the measurement result at that position, and perform an accurate surface shape based on this. However, there is a limit to relying solely on accurate scan driving to make the measured position particularly accurate, and the accuracy of surface shape measurement is insufficient.
However, in order to make the measurement more accurate, it is not practical if the measurement is performed after the positioning of the measurement position is accurately performed in order to make the measurement position accurate.

The present invention has been made in view of the above conventional problems, and an object of the present invention is to provide a surface profile measuring device capable of more rapidly and more accurately measuring a surface profile.

[0006]

In order to achieve the above object, a surface shape measuring apparatus according to the present invention is a relative displacement of a probe which is relatively displaced according to the shape of a curved surface to be measured when the curved surface to be measured is scanned by a probe. A device for measuring the surface shape of an inspected curved surface by detecting an amount, the displacement mechanism for relatively displacing the probe according to the shape of the inspected curved surface, and detecting the relative displacement amount of the probe by the displacement mechanism. A displacement amount detecting means, a scanning means for relatively rotating and scanning the probe with respect to a curved surface to be inspected, with two axes passing through a center of curvature of a curved surface serving as a reference of the curved surface to be inspected as rotation axes, and rotation by the scanning means. The angle detection means for detecting the rotation angle of scanning and the detection data of the displacement amount detection means are sequentially latched when the current detection angle by the angle detection means and a preset setting angle match. That has a latch means is characterized by measuring the surface shape of the curved surface on the basis of the data from the latch means.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a measuring apparatus according to the present invention, and is a schematic configuration diagram showing a shape measuring apparatus for spherical and aspherical lenses.

In FIG. 1, a slewing bearing 2, an encoder 3, and a slewing motor (not shown) are fixed to a surface plate 1.
The orbiting bearing 2 and the orbiting shaft 21 fixed to the R alignment guide 6 for matching the center of curvature of the lens with the orbiting shaft 21.
The area between and is constituted by an aerostatic bearing system. Further, the space between the swivel slide 5 fixed to the surface plate 1 is also constructed by the aerostatic pressure guide system. The swing shaft 21 is connected to a swing motor (not shown) by a steel belt (not shown). With the above, a turning shaft drive mechanism for rotating the R alignment guide 6 around the turning shaft 21 is configured.

The indexing bearing 8 and the indexing motor 9 are fixed to the R-matching slide 7, and the space between the indexing bearing 8 and the indexing shaft 22 is constructed by an aerostatic bearing system. An object to be measured 30 such as an aspherical lens is fixed by a chuck indexing shaft 22 (not shown) so that its optical axis coincides with the indexing shaft 22. With the above, an indexing mechanism of the DUT 30 for rotating the DUT 30 around its optical axis is configured.

An air static pressure guide system is provided between the R alignment guide 6 and the R alignment slide 7.
On the other hand, by sliding the R matching slide 7,
An R alignment mechanism for aligning the center of curvature of the DUT 30 with the swivel axis 21 is configured. An aerostatic pressure guide system is provided between the coarse movement guide 10 and the coarse movement slide 11 fixed to the surface plate 1. The coarse movement motor 12 and the coarse movement slide 11 fixed to the coarse movement guide 10 are a screw 1 formed by a ball screw or a trapezoidal screw, which is a rotation / linear movement converting mechanism.
It is connected by 2 '. The amount of movement of the coarse movement slide 11 is measured by the coarse movement lattice scale 13 fixed to the coarse movement slide 11 and the lattice pitch reading device 14 fixed to the coarse movement guide 10.

The space between the fine movement guide 15 and the fine movement slide 16 fixed to the coarse movement slide 11 is constructed by an aerostatic pressure guide system. A fine movement motor 17 composed of a linear motor is fixed to the coarse movement slide 11, and the slide portion is fixed to the fine movement slide 16 by inserting the fine movement guide 15.

The autofocus microscope 20 is fixed to the fine movement slide 16, and the fine movement grating scale 18 fixed to the autofocus microscope 20 and the grating pitch reading device 19 fixed to the coarse movement slide 11 allow the autofocus microscope 20 to move. Measure the amount of movement. Further, the surface plate 1 is fixed to a vibration isolation table (not shown) to remove the influence of external vibration.

FIG. 2 is a schematic configuration diagram showing the internal configuration of the autofocus microscope 20, which is disclosed in Japanese Patent Laid-Open No. 61-17907.
This is the same as the three-dimensional shape measuring system disclosed by the applicant of the present application in the publication. Therefore, a detailed description is omitted here, and the function of this optical system will be briefly described.

In the autofocus microscope shown in FIG. 2,
The focus state determination optical system 42 detects the focus state of the object 30 to be measured with respect to the objective lens 41, drives the fine movement motor 17 according to the focus state, and causes the autofocus microscope 20 to move.
An automatic focusing mechanism that locks the focal position of the objective lens 41 at a point where the surface of the object to be measured 30 and the optical axis of the objective lens 41 intersect, that is, a point to be measured, is always provided by moving. At the same time, the tilt angle measuring optical system 43 measures the tilt angle of the surface of the DUT 30 at the measured point. The tilt angle at this time is measured as a tilt angle around the turning axis 21 in the turning direction indicated by an arrow (θ).

According to this embodiment, the focus state determining optical system 4 is used.
The projection of the optical probe onto the surface to be measured of the object to be measured 30 by 2 is made incident such that the central ray of the optical probe is inclined with respect to the optical axis, that is, obliquely incident to the surface to be measured. This inclination occurs within the paper surface of FIG. 2, and the direction of deviation of the reflected beam from the surface to be inspected lies within the paper surface.

On the other hand, since the object 30 to be measured is swiveled around the swivel axis 21, the optical probe scans the surface of the object 30 to be measured in a direction orthogonal to the paper surface.

Object under test 30 such as a spherical or aspherical lens
Has a constant shape along the circumferential direction, and the inclination angle in the direction orthogonal to the turning direction shown in FIG.

Therefore, as shown in FIG. 2, the deviation direction of the reflected beam of the focusing state determination optical system 42 and the turning direction of the object 30 to be measured are substantially orthogonal to each other, preferably 90 ± 20 °. With this configuration, it is possible to eliminate a slight deviation of the reflected beam due to the inclination of the surface to be measured of the DUT 30 and interference with the beam for measuring the inclination angle, and the focusing state determination optical system 4 can be eliminated.
2 can accurately detect the height (position) of the surface to be inspected in the optical axis direction. Therefore, the accuracy of the in-focus state determination can be significantly improved.

In the focusing state determination optical system 42 shown in FIG. 2, 80 is a light source, 100 is a collimator lens, 120 is a knife edge, and 140 is a knife edge.
Is a polarized beam splitter, 160 is a half mirror, 180 is a quarter-wave plate, 241 is an objective lens, 220 is a bandpass filter,
Reference numeral 240 is a lens, and 244 is an optical sensor.

In the tilt angle measuring optical system 43, 280 is a light source, 300 and 320 are lenses, and 340.
Is a polarized beam splitter, 360 is a bandpass filter, and 45 is an optical sensor. In this optical system 43, the half mirror 160, the quarter-wave plate 180, and the objective lens 41 are shared with the optical system 42.

FIG. 3 shows a block diagram of a control system of the measuring apparatus shown in FIGS. The output signal of the sensor 44 of the focus state determination optical system 42 installed inside the autofocus microscope 20 is input to the focus state detector 50 and processed into the focus state signal and the light amount signal shown in FIG. (JP-A-61
-17907). That is, the in-focus state signal when the measured surface-shaped measured point of the measured object 30 is at the focal position of the objective lens 41 in FIG. 2 is point a in FIG. As the objective lens 41 deviates from the focus position, the focus state signal changes linearly near point a. At that time, the light amount signal indicating the total amount of light received by the sensor 44 exhibits a change as shown in the lower side of FIG. Therefore, as can be seen from FIG. 4, the focus state detectable region is determined by the light amount level of the light received by the sensor 44 being a certain value or more.

The focus state signal and the light amount signal generated by the focus state detector 50 are input to the servo driver 52 and the control computer 60. Further servo driver 52
Output is connected to the fine movement motor 17, and the fine movement slide 1
6, auto focus microscope 20, DUT 30, focus state detector 50, servo driver 52, fine movement motor 17
Forms an autofocusing servomechanism loop.

The output signal of the sensor 45 of the tilt angle measuring optical system 43 installed inside the autofocus microscope 20 is input to the tilt angle detector 51 and processed as the tilt angle of the measured point in the turning direction ( See Japanese Patent Laid-Open No. 61-17907). Further, the tilt angle signal processed by the tilt angle detector 51 is input to the control computer 60.

The output signal of the grating pitch reading device 19 is input to the fine movement slide movement amount detector 53 and the fine movement slide 1 is detected.
The signal is processed as a movement amount of 6. Further, the movement amount of the fine movement slide 16 is input to the servo driver 52 and the control computer 60. At this time, the fine movement slide 16, the fine movement lattice scale 18, the lattice pitch reading device 19, the fine movement slide movement amount detector 53, the servo driver 52, and the fine movement motor 17 form a positioning servo mechanism loop of the autofocus microscope 20.

By a command from the control computer 60,
The coarse movement motor driver 54 is driven and the coarse movement motor 12 connected to the coarse movement motor driver 54 rotates, so that the coarse movement slide 11 connected by the screw 12 ′ moves.

The output signal obtained by reading the scale of the coarse movement lattice scale 13 of the lattice pitch reading device 14 fixed to the coarse movement guide 10 is input to the coarse movement slide movement amount detector 55, and the movement amount of the coarse movement slide 11 is inputted. Is processed and input to the control computer 60.

By a command from the control computer 60,
The swing shaft motor driver 56 is driven, and a swing motor (not shown) connected to the swing shaft motor driver 56 rotates. At this time, the turning shaft 21 connected to the turning motor is rotated by a steel belt (not shown), and the DUT 30 is turned about the turning shaft 21.

A signal from the encoder 3 is a turning angle detector 5
7, the rotation angle of the rotary shaft 21, that is, the DUT 3
The signal is processed as a turning angle θ around the a priori axis 21 of 0 and input to the control computer 60.

By a command from the control computer 60,
Indexing axis motor 9 connected to indexing axis motor driver 58
Rotates. As a result, the DUT 30 rotates about the indexing shaft by a certain angle, and the cross section to be measured is indexed.

A focus state display (not shown) is displayed on the operation plate 59.
Light quantity display, tilt angle display, fine movement slide movement amount display, coarse movement slide movement amount display, swivel angle display, etc., switch for switching between autofocusing servo mechanism and autofocus microscope positioning servo mechanism, fine movement slide drive switch, Coarse slide drive switches, swivel axis drive switches, indexing axis drive switches, measurement start / stop switches, and other control switches are provided, and by connecting to the control computer 60, a man-machine interface is performed.

The control computer 60 is connected to the data processing computer 61, and outputs the focus state, the tilt angle and the fine movement slide movement amount, the coarse movement slide movement amount, and the turning angle of the object to be measured 30 output from the control computer 60. The data is input to the data processing computer 61. Further, the measurement condition data for the DUT 30, such as the measurement turning range, the number of measurement points, and the turning speed, output from the data processing computer 61 is input to the control computer 60.

Each of the above-mentioned measurement data input by the data processing computer 61 is processed and converted into shape data of the surface to be measured of the object 30 to be measured, and the disk 62 and the plotter 6 are processed.
3, output to the printer 64 and the like.

Next, the method for measuring the shape of the aspherical lens in this embodiment will be described below.

FIG. 5 is an explanatory view showing the measuring method in the apparatus of one embodiment of the present invention, and shows the measuring mechanism section and the control section in the form of a block diagram.

The measuring mechanism section of FIG. 6 is a top view of FIG. 1 seen from above. As shown in FIG. 5, this measuring device locks the focus position of the objective lens 41 to the measured point of the measured object 30 by the above-mentioned autofocusing servo mechanism, and the center of curvature of the measured object 30 (swivel axis 21). To be measured 30 around
And a ridge line of the DUT 30 are scanned to measure the cross-sectional shape of the DUT 30 by the turning angle θ and the distance r from the turning axis 21 to the measured point. Is. Furthermore, the measured object 30 is rotated around the indexing shaft 22 to perform multi-section measurement, and the surface shape of the measured object 30 is measured.

First, the fine movement guide 15 and the fine movement slide 16
The fine movement slide 16 is placed at the operating position of a proximity sensor (not shown) provided between
The output of is reset to 0. Further, the coarse movement slide 11 is placed at the operation position of the proximity sensor (not shown) provided between the coarse movement guide 10 and the coarse movement slide 11 shown in FIG. 1, and the focus position and the turning of the objective lens 41 in this state. The output of the coarse motion slide movement amount detector 55 is preset so that the distance from the shaft 21 becomes equal to the sum of the output of the fine motion slide movement amount detector 53 and the output of the coarse motion slide movement amount detector 55. That is, the calibration is performed so that the sum of the output of the fine movement slide movement amount detector 53 and the output of the coarse movement slide detector 55 becomes 0 when the focal position of the objective lens 41 coincides with the turning axis 21. Become.

Next, the object 30 to be measured is fixed to the indexing shaft 22 by a chuck mechanism (not shown) so that the axis of the object 30 to be measured, that is, the optical axis of the lens and the indexing axis 22 coincide with each other.

Next, the coarse movement slide is adjusted so that the sum of the output of the fine movement slide movement amount detector 53 and the output of the coarse movement slide movement amount detector 55 becomes the radius of curvature R (design value) of the object 30 to be measured. 11 and the fine movement slide 16 are driven. At this time, the fine movement slide 16 is assumed to be driven by the positioning servo mechanism. Next, the R alignment slide 7 is driven to
The measured surface of the object 30 to be measured is brought close to the autofocus microscope 20 up to the focus state detectable region of the autofocus microscope 20 shown in FIG. In this state, the positioning servomechanism loop is switched to the autofocusing servomechanism loop. As a result, the measured point is locked at the substantially focal position of the objective lens 41. Here, the sum of the output of the fine movement slide movement amount detector 53 and the output of the coarse movement slide movement amount detector 55 is the measured object 30.
The R adjustment slide 7 is finely adjusted and driven so that the radius of curvature R becomes.

By the method as described above, the origin of measurement is set as the center of curvature of the object to be measured 30 such as a lens, and the object to be measured 30 and the object to be measured 30 are automatically set to form an R-θ coordinate system with respect to the origin on the center of curvature. By presetting the focus microscope 20, the center of curvature of the object to be measured 30 and the swivel axis 21 can be easily provided without considering the thickness of the object to be measured 30 unlike the conventional measuring method based on the XY coordinate system. Can match.

Further, since the optical probe of the autofocus microscope 20 detects the unevenness of the surface to be inspected by swirling and scanning the surface to be inspected of the object to be measured 30, the stroke of the optical probe has an aspherical base curved surface (curvature radius It is only the amount of deviation from R), and the length measurement stroke can be shortened.

Further, each mechanism of the measuring device has a simple structure and the moving amount of the driving mechanism is small, so that the measuring device is small.

The process of switching the positioning servo mechanism loop of the autofocus microscope 20 to the autofocusing servo mechanism loop will be described in detail. When the measured surface-shaped measured point of the measured object 30 is at the focal position of the objective lens 41, the reflected beam from the measured point is focused on the center of the sensor 44 including the CCD of the focusing state determination optical system 42. Spot images are formed (see Japanese Patent Laid-Open No. 61-17907). Therefore, by observing the video signal of the sensor 44 with an oscilloscope monitor (not shown), the measured point can be moved to the focus state detectable region. That is, the focus state detectable region is detected in the state where the video signal of the sensor 44 exists near the center of the sensor 44. In this state, the switching switch switches from the positioning servo mechanism loop to the autofocusing servo mechanism loop, so that the measured point is automatically locked at the focal position of the objective lens 41.

Next, a swing motor (not shown) is driven to rotate the swing shaft to swing the object 30 to be measured. As a result, the optical probe by the autofocus microscope 20 becomes
The cross-sectional shape including the apex of the lens is measured by scanning the ridge line and detecting the reflected beam from the surface to be inspected. Further, the indexing shaft 22 is driven to rotate the DUT 30 about the axis,
By changing the scanning ridge line and performing the same measurement, the surface shape of the DUT 30 is measured radially.

Now, during the measurement as described above, or in any other case, when the fine movement slide 16 is driven by the autofocusing servomechanism loop, there are scratches, dust, etc. at the measured point and the focus state is reached. When the reflected beam from the measured point of the discrimination optical system 42 is scattered,
The amount of light incident on the objective lens 41 is extremely reduced, and the amount of light reaching the sensor 44 is reduced. Therefore, the operation of the focus state determination optical system 42 falls into an inoperable state, the autofocusing servo mechanism loop is cut, and the fine movement slide 16 cannot be controlled. Therefore, a dangerous situation such as the collision of the autofocus microscope 20 with the measured object 30 is expected. Therefore, during the measurement, even if there is no scratch or dust on the measured point due to the rotational scanning, the measurement cannot be continued and the measurement is interrupted. In order to deal with these abnormal situations, the following safety measures are taken in the device of this embodiment. That is, when the fine slide 16 is driven by the autofocusing servo mechanism loop, due to some influence including scratches, dust, etc.,
When the focus state discriminable region shown in FIG. 4 is deviated, the positioning servo mechanism loop is automatically switched to lock the autofocus microscope 20 at that position. This allows
The danger that the autofocus microscope 20 collides with the object 30 to be measured is prevented. Further, considering a case where the measured point passes through scratches, dust, etc. during measurement, as shown in FIG. 6, while passing through the scratches, dust, etc. by swivel scanning, the focus position of the objective lens 41 is scratched, dust, etc. The vehicle is locked at the position b immediately before passing through. Here, in the minute scanning range Δθ, it can be said that the displacement Δr of the measured point in the direction of the index axis 22 is minute. Therefore, even if the control of the auto-focusing servo mechanism becomes impossible due to minute scratches or dust, and the loop is switched to the positioning servo mechanism loop, the surface to be inspected will be in focus again when the scratches, dust, etc. pass by scanning. The focus position of the objective lens 41 is displaced from c to d by returning to the discriminable region and automatically returning to the autofocusing servo mechanism loop by detecting this, and the measurement is continued. The above flowchart is shown in FIG. 7 for reference.

Next, the surface shape data processing method in this embodiment will be described.

In FIG. 5, the swivel shaft 21 is driven at a constant speed V ₀ according to a command from the control computer 60, and the ridgeline of the object 30 to be measured is scanned at a constant speed by the optical probe of the autofocus microscope 20. At this time, the measured turning angle θ ₀ is output by the control computer 60, and the comparator 6
8 is input to A. Further, the output of the turning angle detector 57 is input to B of the comparator 68. Here, when the measured turning angle θ ₀ set by the control computer 60 and the present turning angle θ ₀ value match, the comparator 68 outputs an A = B signal. Further, the focus state detector 5
The latches 65, 66 and 67 respectively latch the focus state signal, which is an output of 0, the fine movement slide movement amount, which is the output of the fine movement slide movement detector 53, and the inclination angle, which is the output of the inclination angle detector 51. Each latched data is sent to the data processing computer 6 via the control computer 60.
1 is transmitted. By sequentially performing this for a large number of measured turning angles, one cross-section data of the DUT 30 is acquired. These data are processed by the data processing computer 61 and processed into one cross-section shape data.

Next, a method of processing measurement data into shape data will be described. As described above, in the initial state, the objective lens 41
The sum of the output of the fine movement slide movement amount detector 53 and the output of the coarse movement slide movement amount detector 55 in a state where the focus position of the position A and the turning axis 21 coincide with each other is calibrated to zero. The output of the focus state detector 50 is the amount of deviation of the measured point from the focus of the objective lens 41. Therefore, the sum of the output of the focus state detector 50, the output of the fine movement slide movement amount detector 53, and the output of the coarse movement slide movement amount detector 55 is the swivel axis 21 (center of curvature of the DUT 30) in FIG.
Is nothing but the distance r from the measured point. Further, the radius of curvature of the object to be measured 30 is R (generally r at the apex of the object to be measured 30), and data processing of δ = R−r is performed to obtain the aspherical surface amount δ. However, since the coarse slide 11 is locked by the air-down method during the measurement, the actual value of r is the sum of the output of the focus state detector 50 and the output of the fine slide movement amount detector 53. The quantity δ is calculated. At the same time, the inclination angle α of the measured point is measured as the output of the inclination angle detector 51. This is the angle α shown in FIG. 5, and the tangent line of the measured point in the turning direction is the same as the measured object 30. Is an angle formed with a tangent plane at a point intersecting the optical axis of the spherical objective lens 44 having the center of curvature of.

As described above, the indexing angle (rotational angle of the object 30 to be measured around the indexing shaft 22) and the turning angle θ as position information of the measured point and the aspherical surface amount δ as the measured point information. The inclination angle α constitutes surface shape data of the object 30 to be measured. Further, the data is processed by the data processing computer 61 to the disk 62 and the plotter 6
3 and the output to the printer 64, the surface shape of the DUT 30 is output and the man-machine interface is established.

As described above, when the measurement data is converted into the surface shape data, by using both the output of the focus state detector 50 and the output of the fine movement slide movement amount detector 53,
Even when the mechanism for focusing the optical probe on the surface to be inspected as in the apparatus shown in FIG. 1 is large and the autofocus servo cannot follow it, the shape data of the surface to be inspected can always be obtained accurately.

Further, by obtaining the inclination angle data via the inclination angle measuring system as described above, the position and inclination of the measured point on the surface to be inspected can be known, and a more detailed surface shape can be expressed.

Now, the scanning mode of the optical probe in this measuring apparatus will be described. Since this measuring device is provided with the turning means for turning the object 30 to be measured and the indexing means for rotating the object 30 to be rotated, the scanning modes shown in FIGS. 8, 9 and 10 are possible. Is. In addition, FIG.
9 and 10 are views of the object to be measured 30 viewed from its apex side, and the center of the circle in each figure is the apex of the object to be measured 30.

In order to realize the radial scanning shown in FIG. 8, the indexing shaft 22 is driven as described above so that the direction of the cross section aa 'in FIG. 8 and the turning direction coincide with each other. Next, the cross section aa ′ is scanned while acquiring data for each measurement turning angle. Similarly, the indexing shaft 22 is driven so that the direction of the section b′-b and the turning direction are aligned with each other, and the section b′-b is scanned while acquiring data for each measured turning angle. In this way, the angular cross sections aa ', b'-b, cc', d'-d,
Data are acquired by scanning 8 cross sections of ee ', f'-f, gg', and h'-h. The number of sampling points at this time is 1000 points / cross section.

Next, the annular scanning shown in FIG. 9 will be described with reference to FIG. The mechanical portion of FIG. 11 is similar to that of FIG.
It is the figure which looked at from above. The turning shaft 21 is driven to match the angle formed by the indexing shaft 22 and the optical axis of the objective lens 41 with nθ. Next, the indexing shaft motor driver 58 is driven by a command from the control computer 60 to drive the indexing shaft motor 9 at a constant speed. At this time, a signal from a rotary encoder (not shown) installed on the indexing shaft 22 is input to the indexing angle detector 69, the indexing angle is output as the output of the indexing angle detector 69, and the input to the comparator 68. Connected to B. Further, the measurement indexing angle is output by the control computer 60 and connected to the input A of the comparator 68. At this time, the A = B signal, that is, the output of the in-focus state detector 50, the output of the fine movement slide movement amount detector 53, and the output of the tilt angle detector 51 at the timing when the measured indexed angle and the indexed angle present value match. Are respectively latched and measured as the aspherical surface amount δ and the inclination angle α at the measurement indexing angle. The same measurement is performed for indexing angles of 0 ° to 360 ° to complete the measurement of one ring zone. Further, by performing the above-described measurement for the turning angles 0, θ, 2θ, ..., Nθ, the measurement for n ring zones is completed, and the surface shape of the DUT 30 is measured.

Next, the spiral scanning shown in FIG. 10 will be described with reference to FIG. The mechanical portion of FIG. 12 is also shown in FIG.
Similarly, it is the figure which looked at FIG. 1 from the upper part. The measurement is the DUT 30
Start from the top of. First, according to a command from the control computer 60, the indexing axis motor driver 58 and the turning axis motor driver 56 are driven, and the indexing axis 22 and the turning axis 21 connected to each driver are driven at a constant speed. At this time, a signal from a rotary encoder (not shown) installed on the indexing shaft 22 is input to the indexing angle detector 69, the indexing angle is output as the output of the indexing angle detector 69, and the input to the comparator 68. Connected to B. Further, the measurement indexing angle is output by the control computer 60 and connected to the input A of the comparator 68.
At this time, the A = B signal, that is, the output of the in-focus state detector 50, the output of the fine movement slide movement amount detector 53, and the output of the tilt angle detector 51 at the timing when the measured indexed angle and the indexed angle present value match. Are respectively latched and measured as the aspherical surface amount δ and the inclination angle α at the measurement indexing angle. By performing the same measurement from the turning angle 0 ° to θ, the measured object 3
The surface shape of 0 is continuously measured in a spiral shape.

As described above, by providing the turning means and the indexing means, the shape of the front zone of the surface to be inspected can be measured with a simple mechanism, and the scanning form of the optical probe can be measured as a desired form. It will be possible. Therefore, not only the measurement speed is increased and the measurement is automated, the degree of freedom of the measurement form is increased, and arbitrary surface shape data can be extracted.

FIG. 13 is a schematic block diagram showing a second embodiment of the aspherical lens shape measuring apparatus of the present invention. This embodiment is different from the first embodiment shown in FIG. 1 in which the object to be measured is swung in that the probe side swivels. In FIG. 13, the swivel slide 5 is fixed to the coarse movement guide 10, and the R alignment guide 6 is fixed to the surface plate 1. The objective lens 41 is provided on the surface of the DUT 30 having the center of curvature on the turning axis 21.
The focus position of the object to be measured is locked, and the entire probe side including the autofocus microscope 20 is swiveled around the swivel axis 21 to scan the surface of the object to be measured 30, and the object to be measured 30 is scanned as in the first embodiment. Measure the surface shape.

In the above embodiment, the fine movement slide 16
The grating interference method is used as the length measuring means for measuring each movement amount of the coarse movement slide 11 and the coarse movement slide 11, but a laser interference method can also be used.

According to the surface shape measuring apparatus for the aspherical lens of the embodiment as described above, it is possible to measure in a wide range in a measuring range of curvature, opening angle, aspherical amount, etc., and with high accuracy. Aspherical lens shape measurement with a minute spot can be performed at high speed. At the same time, since the inclination angle of the surface of the object to be measured can be measured, accurate information on the shape of the aspherical lens can be obtained in a short time.

Furthermore, according to the present measuring apparatus, it is possible to consider the adhesion of scratches as seen in the contact probe system to various materials such as glass lenses, plastic lenses, and mold-like molds as objects to be measured. It becomes unnecessary.

[0060]

According to the present invention as described above, the detection data of the displacement amount detecting means are sequentially latched when the current detected angle by the angle detecting means and the preset setting angle coincide with each other. Since the surface shape of the curved surface to be measured is measured based on the data, it is possible to quickly and accurately obtain the measurement result at the measured position without the complicated procedure of positioning the measured position exactly and then starting the measurement. It has become possible to measure the surface shape more quickly and accurately.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a measuring apparatus according to the present invention.

FIG. 2 is a schematic configuration diagram showing the inside of the autofocus microscope shown in FIG.

FIG. 3 is a block diagram of a control system of the measuring device shown in FIG.

FIG. 4 is an explanatory diagram showing a relationship between a focus state signal at a measured position and a light amount level received by a sensor.

FIG. 5 is an explanatory diagram showing a measuring method in one example of the present invention.

FIG. 6 is an explanatory diagram showing a measurement procedure when dust or scratches are present on the surface to be detected.

FIG. 7 is a flowchart showing a method of switching between an auto focusing servo mechanism loop and a positioning servo mechanism loop.

FIG. 8 is a schematic diagram showing one scanning mode of an optical probe that scans a surface to be inspected.

FIG. 9 is a schematic diagram showing one scanning mode of an optical probe that scans a surface to be inspected.

FIG. 10 is a schematic diagram showing one scanning form of an optical probe for scanning the surface to be inspected.

11 is an explanatory diagram showing a scanning method in the case of scanning in the scanning mode shown in FIG.

12 is an explanatory diagram showing a scanning method in the case of scanning in the scanning mode shown in FIG.

FIG. 13 is a schematic configuration diagram showing another embodiment of the measuring apparatus according to the present invention.

[Explanation of symbols]

 1 surface plate 2 slewing bearing 3 encoder 4 slewing guide 5 slewing slide 6 R alignment guide 7 R alignment slide 8 indexing bearing 9 indexing shaft motor 10 coarse movement guide 11 coarse movement slide 12 coarse movement motor 12 'screw 13 fine movement lattice scale 14 Lattice pitch reading device 15 Fine movement guide 16 Fine movement slide 17 Drive motor 18 Fine movement lattice scale 19 Lattice pitch reading device 20 Autofocus microscope 30 Object to be measured 41 Objective lens 42 Focusing state determination optical system 43 Tilt angle measuring optical system 44, 45 Sensor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Makoto Higomura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Hatsunori Yamamoto 3-30-2 Shimomaruko, Ota-ku, Tokyo In Canon Inc. (72) Inventor Satoshi Nose 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Yukichi Niwa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Mitsutoshi Owada 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (1)

[Claims] 1. An apparatus for measuring the surface shape of a test curved surface by detecting the relative displacement amount of the probe, which is relatively displaced according to the shape of the test curved surface when the test curved surface is scanned by the probe. A displacement mechanism for performing relative displacement according to the shape of the curved surface to be measured, a displacement amount detecting means for detecting a relative displacement amount of the probe by the displacement mechanism, and a reference for the curved surface to be measured with respect to the curved surface to be measured. A scanning unit that relatively rotationally scans two axes passing through the center of curvature of the curved surface as a rotation axis, an angle detection unit that detects a rotation angle of the rotational scanning by the scanning unit, and a current detection angle by the angle detection unit. Latching means for sequentially latching the detection data of the displacement amount detecting means when the preset set angle matches, and the surface shape of the curved surface to be measured based on the data from the latching means. A surface shape measuring device characterized by measuring a shape.