JPH11211427A - Surface form measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface form measuring device capable of precisely measuring the surface form of a surface to be measured by correcting the error due to declination associated with translation movement. SOLUTION: A control part controls a translation stage 5 and rotating stages 6, 8 to conform the optical axis 7a of a measuring probe 7 with the normal of an aimed partial surface of the surface to be measured 4a of a matter to be measured 4. Laser length measuring machines 10A-10F measure the distance with flat mirrors 9A-9C and output distance signals. The control part calculate the declination (pitching, yawing, rolling) of a translation stage top part 5a on the basis of the distance signals from the laser length measuring machines 10A-10F. The measuring probe 7 optically measures the distance with each point on the aimed partial surface and outputs a measurement signal. The control part corrects the measurement signal from the measuring probe 7 on the basis of the calculated declination.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface shape measuring apparatus for optically measuring the surface shape of a complex aspherical surface such as an aspherical lens mounted on a laser printer or the like in a non-contact manner. The surface shape is a fraction of the wavelength of the laser
The present invention relates to a surface shape measuring device for measuring with high accuracy.

[0002]

2. Description of the Related Art An example of a conventional surface shape measuring apparatus is disclosed in Japanese Patent Application Laid-Open No. 2-259509. The surface shape measuring apparatus includes a translation stage for translating the object to be measured in three orthogonal directions, a rotating stage for rotating the object to be measured, and a surface shape of a partial surface of interest of the measured surface of the object to be measured. And an interferometer for measuring. Divide the entire surface to be measured into multiple partial surfaces, control the translation stage and rotation stage, match the optical axis of the interferometer with the normal direction of the partial surface of interest, and measure the surface shape of the partial surface of interest This is performed for all the partial surfaces on the measured surface, and then the measurement data of the entire measured surface is obtained by joining the measurement data of the respective partial surfaces.

[0003]

However, according to the conventional surface shape measuring apparatus, when the object to be measured is moved by the translation stage, minute angle errors called pitching, yawing, and rolling occur. In addition, since the rotary stage has a limit in the machining accuracy of the guide portion, an error occurs due to shaft deviation accompanying the rotation operation. For this reason,
There is a problem that an error occurs in the measurement result of the entire surface obtained by performing the calculation for joining the measurement data of each partial surface.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a surface shape measuring apparatus capable of correcting an error due to a declination accompanying translational movement and measuring a surface shape of a surface to be measured with high accuracy.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a measurement method in which a surface of an object to be measured is irradiated with measurement light, the measurement light reflected from the surface is received, and a measurement signal is output. A probe, a translation unit that relatively translates the measurement probe with respect to the object, a rotation unit that relatively rotates the measurement probe with respect to the object, and the translation unit. A deflection angle detecting means for detecting a deflection angle of the measurement probe or the object to be translated, and controlling the translation means and the rotation means to move the measurement probe and the object to a predetermined position. Control means for positioning and correcting the measurement signal output from the measurement probe based on the declination detected by the declination detection means. To provide a device.

[0006]

FIG. 1 shows a surface shape measuring apparatus according to a first embodiment of the present invention. Note that the X, Y, and Z directions are directions shown in FIG. This device 1
It has a vibration isolating table 2 for preventing vibration from being transmitted to the entire apparatus 1 and a column 3 erected on the vibration isolating table 2. , A translation stage 5 for moving and positioning in the Z direction, and a first rotary stage 6 for rotating the object 4 to be measured, and a support probe 3 is provided with a measurement probe 7 for optically measuring the distance between the support 3 and an opposing surface. A second rotating stage 8 for rotating is provided. A translation stage uppermost portion 5a is attached to the upper portion of the translation stage 5, and three plane mirrors 9A, 9B, and 9C whose reflecting surfaces are orthogonal to the X, Y, and Z directions are mounted on the translation stage uppermost portion 5a.
Is attached. A laser length measuring device 10A which is supported on a vibration isolator 2 by a support member (not shown), measures a distance to the plane mirrors 9A to 9C and outputs a distance signal.
-10F are provided.

The translation stage 5 has a translation stage uppermost portion 5a at an upper portion, and the X stage 5b and the Y stage respectively move and position the translation stage uppermost portion 5a in the X, Y, and Z directions using rolling bearings. 5c and a Z stage 5d, and the X stage 5b, the Y stage 5c and the Z stage 5d
An X-axis motor, a Y-axis motor, and a Z-axis motor, which will be described later, are moved in the X, Y and Z directions.

The first rotation stage 6 has a first rotation axis θ ₁ in the X direction, is attached to both ends of the translation stage uppermost portion 5a, and moves the workpiece mounting table 11 to the first rotation axis θ.
A pair of rotary stages 6A and 6B rotatably supported by an air bearing around ₁ and an object mounting table 11 are placed in a first position.
A motor ₁ that rotates around the rotation axis θ ₁ of the above, and a θ ₁ detector 60 such as a rotary encoder that detects the amount of rotation of the DUT 11 and outputs an angle detection signal.
And

The second rotary stage 8 has a second rotational axis θ ₂ in the Y direction, and uses, for example, an air bearing as a non-contact bearing around the second rotational axis θ _2. It includes a theta ₂ motor to be described later rotates, and theta ₂ detector 80 such as a rotary encoder for outputting a detection to the angle detection signal the amount of rotation of the measuring probe 7 Te.

FIG. 2 shows the positional relationship between the rotation axes θ ₁ and θ ₂ and the optical axis 7a of the measurement probe 7. Measurement probe 7
Are the points on the partial surface 4b of interest when the average direction of the normal line of the partial surface 4b (for example, a range of 1 mm ² ) 4b of the surface 4a to be measured coincides with the optical axis 7a. Is measured optically and the distance is output as surface information. For example, a white light interferometer, a laser displacement meter, or the like can be used. Also, the optical axis 7a of the measurement probe 7
Are provided in the Z direction, and the measurement probe 7 has a center point of the measurement range whose first rotation axis θ ₁ and second rotation axis θ
It is provided so as to substantially coincide with the intersection with ₂ .

FIGS. 3A and 3B show plane mirrors 9A to 9C.
And the positional relationship between the laser length measuring devices 10A to 10F.
In FIG. 3B, reference numerals 10a, 10b, and 10c denote the irradiation points of the laser from the laser length measuring devices 10A to 10C, respectively. Laser length measuring devices 10A, 10B, 10C
This is for measuring the moving distance of the plane mirror 9A in the Y direction.
The laser length measuring device 10F measures the moving distance of the plane mirror 9C in the Z direction. Based on the movement distance measured by the laser length measuring device 10A and the laser length measuring device 10B, the posture change (declination) of the translation stage uppermost portion 5a around the axis in the X direction can be obtained. The posture change of the translation stage uppermost portion 5a around the Y-axis can be obtained based on the movement distance measured by the length measuring device 10E, and the moving distance measured by the laser length measuring device 10A or 10B and the laser length measuring device 10C. The attitude change of the translation stage uppermost portion 5a around the axis in the Z direction can be obtained based on the above equation. When the posture change about the axis in the Z direction is about 3 seconds, the influence on the joining of the adjacent partial surfaces 4b is very small, and the whole measurement result obtained by repeating the joining of the partial surfaces 4b hardly changes. Therefore, it is also possible to omit the laser length measuring device 10C required for measuring the posture change caused by the rotation around the axis in the Z direction, thereby simplifying the measurement.

FIG. 4 shows a control system of the apparatus 1. The device 1 has a control unit 20 that controls the entire device 1,
The control unit 20 includes a memory 21 for storing a program or the like of the control unit 20 and an X-axis motor 5 for the translation stage 5.
0, Y axis motor 51, Z axis motor 53, theta ₁ detector 60 of the first rotary stage 6, theta ₁ motor 61, the measurement probe 7, theta ₂ detector 80 of the second rotation stage 8, theta ₂ motor 81 and the laser length measuring devices 10A to 10F.

Next, the operation of the apparatus 1 will be described. The operator places the DUT 4 on the translation stage 5 and presses a start switch (not shown). The control unit 20 measures the shape of the measured surface 4a of the measured object 4 according to the program stored in the memory 21 based on the depression of the start switch. That is, the control unit 20 controls the translation stage 5 so that the focused partial surface 4b of the partial surface 4b obtained by dividing the entire surface to be measured 4a enters the measurement range of the measurement probe 7.
Is controlled to perform positioning. Next, the control unit 20 rotates the first and second rotary stages 6 and 8 so that the direction of the optical axis 7a of the measurement probe 7 coincides with the average direction of the normal of the focused partial surface 4b. The control unit 20 obtains the moving distance of the uppermost portion 5a of the translation stage in the X, Y, and Z directions based on the distance signals from the laser length measuring devices 10A to 10F. Yawing, rolling). The control unit 20 calculates the moving distances of the translation stage uppermost portion 5a in the X, Y, and Z directions, the angle detection signals from the detectors 60 and 80 of the rotation stages 7 and 8, and the partial surface from the measurement probe 7. 4b
The surface shape of the partial surface 4b is measured based on the surface information described above, and the measurement result is corrected based on the previously-determined declination of the translation stage uppermost portion 5a, and the corrected measurement result is stored in the memory 21. . The control unit 20 performs the same for all the partial surfaces 4b on the measured surface 4a, and
By sequentially connecting the partial surfaces 4b adjacent to each other on the basis of one measurement result, the measurement result of the entire surface to be measured 4a is obtained and stored in the memory 21.

According to the first embodiment, the declination (pitching, yawing, rolling) associated with the translation of the translation stage uppermost portion 5a depends on the performance of the rolling bearing and the machining accuracy of the guide portion of the translation stage 5. Is generated for at least about 3 seconds, but the declination is obtained based on the measurement result of the moving distance by the laser length measuring devices 10A to 10F, and the surface information measured by the measuring probe 7 is corrected. Compared to the case without correction, the size can be reduced to 0.2 μm which is 1/10 or less. Accordingly, the position and orientation error of the partial surface 4b is reduced, and the error of the measurement result of the entire surface 4a to be measured obtained by joining them is also reduced. Accurate measurement becomes possible.

When rolling bearings are used for the rotary stages 6 and 8, shaft deviation of about 3 μm occurs due to machining accuracy of the guide portion, and the initial value of the relative position and orientation of the partial surface 4b is 3
Although an error of about μm is given, according to the present embodiment, since the air bearings are used for the rotating stages 6 and 8, the influence of the machining accuracy of the guide portion is reduced, and
8 can be reduced to about 0.1 μm, and errors in the relative position and orientation of the two partial surfaces 4b can be reduced.

Further, a rotary stage 6 using an air bearing 6,
8 has a lower rigidity and a lower damping performance than a rotating stage using a rolling bearing or a sliding bearing, and there is a concern that vibration causing an error may increase. However, the two rotating stages 6 and 8 are connected to each other. Since the counterparts are independently provided without rotating the counterpart, the mass borne by each of the rotary stages 6 and 8 is minimized, so that the vibration characteristics of the entire apparatus 1 can be optimized and the position and orientation control mechanism as a whole can be improved. Vibration can be reduced.

Further, three X stages 5b, Y stages 5c, and Z stages 5d are provided integrally, and a portion that moves in the X, Y, and Z directions is measured by laser length measuring devices 10A to 10F, whereby the laser length is measured. The number of vessels 10A to 10F can be minimized. That is, suppose Z in the Z direction
The stage 5d and the X stage 5b and the Y stage 5c in the X and Y directions are separately arranged, and the configuration is such that the DUT 4 and the measurement probe 7 are moved, respectively, in order to obtain the same effect as in the present embodiment. It is necessary to prepare a total of 12 laser length measuring devices, 6 for each translation stage. This complicates the configuration of the apparatus and, although minute, causes the error of the laser length measuring device itself to double, so that it is advantageous to combine three translation stages as in this embodiment.

FIG. 5 shows a surface shape measuring apparatus according to a second embodiment of the present invention. This apparatus 1 is different from the first embodiment in that the first rotary stage 6 and the Y stage 5c for moving and positioning the DUT 4 in the Y direction are omitted. The configuration is the same as that of the first embodiment. According to the second embodiment, it is possible to target the DUT 4 whose Y direction of the measured surface 4a is narrower than the measurement range of the measurement probe 7 in the Y direction. When the shape of the surface 4a to be measured is limited as described above, the structure can be simplified by omitting an unnecessary stage,
In addition, the vibration characteristics of the entire device 1 can be optimized.

[0019]

As described above, according to the surface shape measuring apparatus of the present invention, the deflection angle of the measurement probe or the object to be measured which is translated by the translation means is detected, and the measurement probe is measured based on the deflection angle. Since the measurement signal output from is corrected, it is possible to correct the error due to the declination due to the translation and to measure the surface shape of the surface to be measured with high accuracy.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a surface shape measuring device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a positional relationship between rotation axes θ ₁ and θ ₂ and an optical axis of a measurement probe.

3A is a diagram showing a positional relationship between a plane mirror and a laser length measuring device on the YZ plane, and FIG. 3B is a diagram showing a positional relationship between the plane mirror and the laser length measuring device on the XZ plane.

FIG. 4 is a block diagram illustrating a control system according to the first embodiment.

FIG. 5 is a schematic configuration diagram showing a surface shape measuring device according to a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Surface shape measuring apparatus 2 Anti-vibration table 3 Support 4 Object to be measured 4a Surface to be measured 4b Partial surface 5 Translation stage 5a Top of translation stage 5b X stage 5c Y stage 5d Z stage and 6 First rotation stage 7 Measurement probe 7a Optical axis 8 Second rotating stage 9A to 9C Planar mirror 10A to 10F Laser length measuring device 10a, 10b, 10c Irradiation point of laser 11 Measurement object mounting table 20 Control unit 21 Memory 50 X-axis motor 51 Y-axis motor 53Z Shaft motor 60 θ ₁ detector 61 θ ₁ motor 80 θ ₂ detector 81 θ ₂ motor θ ₁ First rotation axis θ ₂ Second rotation axis

Claims (5)

[Claims] 1. A measuring probe for irradiating a measuring light on a surface of an object to be measured, receiving the measuring light reflected on the surface and outputting a measuring signal, and relative to the object to be measured. Translational movement means for translating the measurement probe relative to the object to be measured; rotational movement means for rotationally moving the measurement probe relative to the object to be measured; and deflection angle of the measurement probe or the object to be measured translated by the translational movement means. Declination detecting means for detecting the position of the measurement probe and the object to be measured at a predetermined position by controlling the translation movement means and the rotation movement means, the measurement signal output from the measurement probe Control means for correcting based on the declination detected by the declination detecting means. 2. The method according to claim 1, wherein the deflection angle detecting means includes: a reflecting mirror provided at a portion translated by the translation moving means; and a plurality of points on the reflecting mirror irradiated with a plurality of laser beams. Laser detecting means for receiving the plurality of laser beams reflected at the plurality of points and detecting a moving distance of the plurality of points; and detecting a deviation of the plurality of points from the moving distances of the plurality of points detected by the laser detecting means. 2. The surface shape measuring apparatus according to claim 1, further comprising a calculating means for calculating an angle. 3. The translation means includes a first stage, a second stage, and a third stage for translating the measurement probe relative to the object to be measured in three directions perpendicular to each other. The declination detecting means is provided at a portion where each of the first stage, the second stage and the third stage translates in the three directions orthogonal to each other so that the reflection surface is orthogonal to the three directions. Three reflecting mirrors, and irradiating six laser beams to predetermined six points on the three reflecting mirrors, and receiving the six laser beams reflected at the six points on the three reflecting mirrors Laser detecting means for detecting the moving distance of the six points, and calculating means for calculating the declination around the axis in the direction from the moving distances of the six points detected by the laser detecting means. Was The surface shape measuring apparatus according to claim 1 having a configuration. 4. The surface shape measuring apparatus according to claim 1, wherein said rotational movement means uses an air bearing as a rotational movement bearing. 5. The apparatus according to claim 1, wherein said rotating means moves the object to be measured to a first position.
A first rotary stage for rotating about a rotation axis of
A second rotation stage having a second rotation axis that forms a predetermined angle with the first rotation axis, and rotating the measurement probe around the second rotation axis; The surface shape measuring apparatus according to claim 1, wherein the stage and the second rotary stage are provided independently without rotating each other.