JP2002107114A - Oblique-incidence interferometer device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oblique-incidence interferometer device with which a face to be inspected is adjusted satisfactorily and simply by a method, wherein an adjusting- pattern generation means with which an optical pattern, capable of judging its direction of rotation can be generated on an image forming face is arranged inside an optical path, the optical pattern is compared with a reference pattern giving the position reference of the optical pattern and the posture of the face to be inspected is adjusted by a face-to-be-inspected adjusting means, in such a way that both patterns coincide. SOLUTION: A cross-pattern generation member 41 is arranged and installed freely insertable and removable in the optical path of light, which is made to be parallel light by collimator lens 14. The generation member 14 is formed, in such a way that a cross-shaped through hole is bored and formed in a light-shielding mask plate. When the generation member is inserted in the optical path, a cross-shaped optical pattern is formed on a screen 18 by a luminous flux, which has passed the through hole. The posture of the face 2a to be inspected is adjusted, in such a way that the position of the cross-shaped optical pattern formed of the luminous flux of reference light B coincides with the position of a cross-shaped optical pattern formed of measuring light C. Thereby, the face 2a to be inspected can be aligned and adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measurement light alignment adjustment for an oblique incidence interferometer, which enables non-contact measurement of the flatness of a rough surface.

[0002]

2. Description of the Related Art Conventionally, various interferometer devices for measuring the flatness of a workpiece surface are known. Among them, an oblique incidence interferometer device is known as a device capable of measuring the flatness of a test surface having a large unevenness.

In the oblique incidence interferometer, the measurement sensitivity can be lowered by obliquely entering a coherent light beam onto the surface to be inspected, so that it is used for non-contact flatness measurement of a rough surface or the like. Have been. Here, assuming that the wavelength of the light used for the measurement is λ and the angle of incidence on the surface to be measured is θ, the amount of unevenness on the surface to be measured, that is, the measurement sensitivity Δh is expressed by the following equation. Δh = λ / (2 cos θ) That is, as the angle of incidence θ increases and the degree of oblique incidence increases, the fringe interval increases and the measurement sensitivity decreases, so that it is possible to measure a plane with poor plane accuracy. .

FIG. 13 shows a first conventional oblique incidence interferometer apparatus.
This is an example in which a plane reference plate is used as a reference prototype. In this oblique incidence interferometer apparatus, a reference plane 116a of a parallel plane plate 116 and a test surface 2a of the subject 2 are arranged to face each other, and the laser light source 11 is obliquely placed on the reference plane 116a.
The collimator lens 114 emits coherent light emitted from the collimator lens 114 and projects an interference fringe corresponding to an optical path difference based on a distance between the reference plane 116a and the test surface 2a on a screen 118, and the observer 119 Is to be observed. As shown in FIG. 13, in this example, the reference light and the measurement light are separated at the reference plane 116a and are combined again at this plane.

FIG. 14 shows a second conventional oblique incidence interferometer apparatus.
This is an example called an Abramson type using a right-angled isosceles triangular prism as a reference prototype. In FIG. 14 and the following conventional example, the same members as those of the oblique incidence interferometer apparatus shown in FIG. This apparatus causes coherent parallel light to be incident on a right-angled isosceles triangular prism 216 from an incident surface 216b. As in the first example, the reference plane 216a is used.
The reference light and the measurement light are separated at, and are combined again on this surface. In this apparatus, the interference fringes projected on the screen 218 are photographed by the TV camera 219 and observed.

FIG. 15 shows a third conventional oblique incidence interferometer apparatus.
Is an example called a birch type using a diffraction grating. This oblique incidence interferometer device impinges coherent parallel light on a diffraction grating 317a, splits the wavefront in two directions, makes one of the light beams obliquely incident on a surface 2a to be measured, and reflects the reflected light as a measuring light The other light beam is used as reference light, the measurement light and the reference light are made incident on the diffraction grating 317b to be wavefront-synthesized, and the light interference between the measurement light and the reference light emitted from the diffraction grating 317b in the same direction is performed. Is projected on a hologram screen 318, and is imaged and observed by a TV camera 319. In FIG. 15, the 0th-order diffracted light wavefront-divided by the diffraction grating 317a is used as a reference light, and the 1st-order diffracted light is used as a measurement light.
The first-order diffracted light of the reference light and the zero-order light of the measurement light are combined in the latter diffraction grating 317b, and are configured to interfere with each other.

[0007]

As described above, various types of grazing incidence interferometers are known.
In order to obtain an actually measurable interference fringe on the screen, it is necessary to adjust the position or orientation of the test surface with high accuracy. Even if the surface to be measured is slightly displaced from the predetermined position in the vertical direction or the front, rear, left and right rotation directions, it becomes difficult to measure the interference fringes.

Therefore, it is necessary to adjust the alignment of the test surface. Conventionally, however, the measurer often manually adjusts the alignment of the test surface until a predetermined interference fringe is obtained by relying on intuition. This is the biggest factor that makes the measurement complicated and long.

Therefore, an imaging lens for alignment adjustment is removably inserted into both optical paths of the reference light and the measurement light,
It is conceivable to adopt a configuration in which the two spots of the two lights overlap each other on the interference fringe observation screen when the position and posture of the test surface are set to the normal positions. Also,
In order to observe the alignment adjustment spot on the interference fringe observation screen in this way, a predetermined distance is set between the imaging lens and the screen in order to make it possible to observe a delicate displacement of the two spots. It is necessary to increase the resolution. For this reason, since the apparatus becomes large in size, the reference light and the measurement light are divided from the optical path toward the interference fringe observation screen, respectively, for the alignment adjustment, and the imaging lens is arranged in the alignment adjustment optical path. A configuration is also conceivable. FIG. 16 shows an example of such an apparatus, in which a mirror 32 is provided in both optical paths of reference light and measurement light.
0 is removably inserted, and at the time of alignment adjustment, two spots of the two lights converged by the imaging lens 321 via the mirror 320 are observed on an alignment adjustment screen 322 so that the two spots overlap each other. Adjustments.

However, the oblique incidence interferometer has a high sensitivity to a positional deviation in the height direction of the test surface and a rotational deviation (pitching) in the front-rear direction of the test surface, but has a high sensitivity to the lateral displacement in the horizontal direction of the test surface. It is characterized by low sensitivity to rotational displacement (rolling), and it has been particularly difficult to adjust the rolling of the surface to be inspected only by positioning the two light spots.

When a spot formed by an imaging lens is used for adjusting the alignment as described above, a distance between the imaging lens and the interference fringe observation screen is required, or the distance between the imaging lens and the alignment adjustment is required. It is necessary to provide a member such as a half mirror for changing the screen to a different optical path, which may increase the size and complexity of the apparatus.

The present invention has been made in view of such circumstances, and provides a compact oblique incidence interferometer apparatus capable of performing good and easy alignment adjustment of a test surface in an oblique incidence interferometer. It is the purpose.

[0013]

According to the oblique incidence interferometer of the present invention, the collimated coherent light is split by the light beam splitting means, and one light beam is used as reference light and the other light beam is used as measurement light. Obliquely incident on the test surface, the reference light and the measurement light reflected from the test surface are combined by the light beam combining means and interfere with each other, and the generated interference fringes are formed on the interference fringe observation imaging surface. In the grazing incidence interferometer device configured to cause the light source to generate the light and is arranged in the optical path between the test surface, on the imaging surface, the rotation direction can be determined optical pattern can be determined. Adjusting pattern generating means for generating, a reference pattern generating means for generating a reference pattern comprising an optical pattern or an electrical pattern capable of determining a rotation direction to be a position reference of the optical pattern, and the adjusting pattern generating means. So as to substantially coincide the optical pattern generated by the over emissions generating means to the reference pattern,
It is characterized by comprising a test surface posture adjusting means capable of adjusting the arrangement posture of the test surface.

It is preferable that the adjustment pattern generating means is removably provided in an optical path between the light beam dividing means and the surface to be inspected.

The reference pattern generating means and the adjustment pattern generating means are also used, and a member having a through hole of a predetermined shape which is removably disposed between the light source and the light beam dividing means is provided. You may comprise so that it may become.

In this case, it is preferable that the member is arranged so as to be freely inserted into and removed from the parallel light beam.

Preferably, the adjusting pattern generating means is a light-shielding plate provided with a cross-shaped through hole.

[0018] The reference pattern generation means may generate position data of an optical pattern on the image plane generated by the adjustment pattern generation means when the test surface is arranged at a regular measurement position. It can be a stored memory.

[0019] The position data of the optical pattern may be obtained based on the optical pattern generated on the image plane by the reference pattern generating means arranged in the reference light.

It is preferable that a light-blocking shutter be provided in the optical path of the reference light and / or the optical path of the measurement light so as to be freely inserted and removed.

Further, the test surface attitude adjusting means uses a rotation axis orthogonal to the test light incident surface of the test surface and included in the test surface, with respect to the test light incident surface. Pitching adjustment for adjusting the rotation of the test surface, rolling adjustment orthogonal to the rotation axis, and performing rotation adjustment of the test surface using a rotation axis included in the test surface, and vertical adjustment of the test surface. It is preferable to be configured so that each adjustment of the height adjustment for performing the adjustment can be performed at least.

In this case, the adjustment of the posture of the surface to be inspected is performed by imaging means for capturing an image formed on the image forming surface, an amount-of-adjustment-amount-of-adjustment-of-the-surface-to-be-tested provided in a computer, It is preferable that the adjustment is performed by using automatic control means including an actuator for driving the test surface attitude adjustment means based on the adjustment amount calculated by the calculation means.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side view illustrating the optical system of the oblique incidence interferometer apparatus according to the first embodiment. In this optical system, the collimated coherent light A is split by a light beam splitting unit, and one light beam is used as reference light B, and the other light beam is obliquely incident on the surface 2a to be measured as measurement light C. An oblique incidence interferometer configured to combine the light B and the measurement light C reflected from the test surface 2a in the light beam combining means and cause them to interfere with each other, and form the generated interference fringes on the interference fringe observation screen 18. The light beam splitting means comprises a single first prism 16 on a surface where the coherent light enters the first prism 16 or a surface where the coherent light exits from the first prism 16 The reference light B and the measurement light C are split, and the light beam combining means includes a single second prism 17;
Of the prism 17 or the second prism 1
The reference light beam B and the measurement light beam C are combined on the surface emitted from the reference light 7. The optical system includes a light source 11, a condenser lens 12, a pinhole 13,
A collimator lens 14 and an optical path diameter adjusting prism 25 described later are provided.

The collimated light A is split on the light beam splitting surface 16a of the first prism 16 into a measuring light C which is transmitted straight and enters the first prism 16 and a reference light B which is regularly reflected. The measurement light C passes through the first prism 16 and is reflected in the order of the mirror 22, the surface to be measured 2a, and the mirror 23,
Incident on the prism 17. On the other hand, the reference light B
1 and regularly reflected on the light beam combining surface 17b of the second prism 17, and the second prism 1
An interference fringe image is projected on the screen 18 by the combined light that is combined with the measurement light C emitted from 7 and carries interference fringe information.

As described above, in this embodiment, the optical path diameter adjusting prism 25 is disposed downstream of the collimator lens 14. This is to make the light beam collimated by the collimator lens 14 obliquely enter the prism 25 from the mirror 24, thereby turning the light beam into collimated light suitable for the oblique incidence interferometer device.

The prism 25 is, for example, a triangular prism-shaped block having a right-angled isosceles triangle in cross section and flattened in a direction opposite to the front and back surfaces of the right-angled isosceles triangle.
Then, the parallel light beam from the mirror 24 is
The position is set so that the light is obliquely incident toward the longitudinal direction of the slope. By arranging the prism 25 between the mirror 24 and the mirror 22 as shown in the figure, the light beam can be enlarged in the direction perpendicular to the paper surface on the light exit surface of the prism 25.

In the case of the oblique incidence interferometer, the light beam width in the plane direction including the incident light beam and the reflected light beam on the surface to be inspected is enlarged by oblique incidence, so that the incident light beam width may be small. In the case of (1), it is necessary to input a light beam having a light beam width sufficient to cover the width of the surface to be measured.
When the collimated light is made incident on the first prism 16 by an ordinary collimator lens, the aperture of the collimator lens must be enlarged in order to have a light flux width in the width direction of the surface to be measured. Since the distance is long, it is difficult to reduce the size of the entire device.

According to this embodiment, the prism 25 is disposed between the collimator lens 14 and the light beam splitting surface so that the light beam is expanded only in one direction by the refraction of the prism 25, so that the diameter of the collimator lens 14 is increased. Can be reduced, and the focal length can be shortened, so that the entire device can be reduced in size.

According to this embodiment, taking into consideration that the light output from the light source 11 is obliquely incident on the surface 2a to be measured in the subsequent stage and is enlarged only in one direction,
Since the light beam is expanded by the prism 25 in advance only in the above-described predetermined direction so as to correspond to the width of the surface to be measured, the light use efficiency can be increased.

In this embodiment, as described above, the first
The number of reflections of the reference light B is three and the number of reflections of the measurement light C is three between the time when the light is divided by the prism 16 and the time when the light is combined by the second prism 17. Since the number of light reflections is an odd number, the tolerance of the error of the collimated light increases.

In this embodiment, the first prism 16
The optical path lengths of the reference light B and the measurement light C from the time when the light beam is divided by the above to the time when the light is combined by the second prism 17 are configured to be substantially equal to each other. Thus, the configuration is effective even when measurement is performed using light with low coherence as a light source. Although not shown, the measurement light C reflected on the surface 2a to be detected is included in the optical path of the reference light B and the measurement light C from the first prism 16 to the second prism 17.
It is preferable to arrange a filter having a light amount adjustment function to make the light amount of the reference light B substantially equal to that of the reference light B. By arranging such a filter, it is possible to provide an optical system capable of coping with the test surface 2a having various surface accuracy and reflectance.

In this embodiment, the measuring light C is applied to the surface 2 to be measured.
a rotatable incident angle changing mirror 22 is provided so that the angle of incidence can be changed.
As an optical path adjusting means for adjusting the optical path so that an interference fringe is formed at a predetermined position on the interference fringe observation screen 18 in response to a change in the angle of incidence of the measurement light C on the test surface 2a due to the
A mirror 23 is provided. However, the position of the mirror 22 is located after the first prism 16, and the position of the mirror 23 is located in the optical path of the measurement light C located downstream of the surface 2a to be measured.

By changing the angle at which the measuring light C is incident on the surface 2a to be measured, the sensitivity of the interference fringes formed by this optical system can be varied, and the object having various surface accuracy can be obtained. The optical system can correspond to the inspection surface 2a.

The mirror 22 is rotatable as indicated by the arrow shown in FIG. 1, thereby changing the angle of incidence on the test surface 2a. Two types of measurement light C when the mirror 22 is rotated are indicated by dotted lines C 'and C ". At this time, the test object 2 is set to correspond to the measurement light C' or C".
This is adjusted so that a is moved to the position shown by the dotted line 2a 'or 2a ". In this embodiment, since the mirror 22 is in the optical path of the measurement light C downstream of the first prism 16, reference is made. The light path of light B is not changed.

Further, it is desirable that the member at the subsequent stage of the test surface 2a be movable as required in response to the change of the optical path of the measuring light C. For example, in the present embodiment, the mirror 23 is rotatable as shown by the arrow shown in FIG. 1, and by changing the position and orientation of the mirror in this manner, the mirror 22 is rotated.
Even if the optical path of the measurement light C reflected by the test surface 2a changes due to the rotation of the measurement light C, the measurement light C can be made incident on the second prism 17 at a predetermined incident angle. The interference fringe image formed by combining C can be projected without moving the screen 18.

As described above, according to the present embodiment, observation can be performed while changing the fringe sensitivity, and the interference fringe image is formed at a predetermined position on the screen 18 even when the fringe sensitivity changes, and observation is performed. be able to.

The apparatus of this embodiment is configured so that the interference fringe image can be observed by the TV camera 20. Therefore, by providing a device with an image processing function of making the field of view of this camera variable by zooming or switching, or evaluating the distortion caused by the lens attached to this camera in advance and performing image processing so as to correct it. Thus, the above-described effects can be obtained.

In order to obtain an actually measurable interference fringe on the screen 18, it is necessary to adjust the position or orientation of the surface to be measured with high precision. Even if the test surface 2a is slightly deviated from the predetermined position in the up-down direction or the front-back and left-right rotation directions, it becomes difficult to measure the interference fringes. Therefore, it is necessary to adjust the alignment of the test surface.However, if the operator manually adjusts the alignment of the test surface until the predetermined interference fringe is obtained by relying on intuition, the measurement becomes complicated and takes a long time. Would.

Therefore, in the present embodiment, as shown in FIG. 1, the cross-pattern generating member 4 as shown in FIG.
1 is removably arranged. The cross pattern generating member 41 is formed by forming a cross-shaped through-hole 42 in the light-shielding mask plate 141. When the cross-shaped hole 42 is inserted in the optical path, the light beam passing through the through-hole 42 crosses the screen 18 on the screen 18. The shape of the light pattern is formed, and the position of the cruciform light pattern formed by the light beam of the reference light B and the position of the cruciform light pattern formed by the measurement light C are matched to adjust the alignment of the test surface 2a. That is what you can do. In addition, since the optical path is a common optical path for the reference light and the measurement light at the optical path position where the cross pattern generating member 41 is inserted, the cross pattern generating member 41 is also used for both lights in this embodiment. I have.

As a specific insertion / removal mechanism of the cross pattern generating member 41, for example, as shown in FIG. 3A, a modified cross-shaped through hole is formed in a large diameter portion of a light shielding plate 141b having a raindrop cross-sectional shape. It is assumed that the cross pattern generating member 43 formed with 42b is rotated by a predetermined angle in the direction of the arrow shown in the figure around the rotation shaft supported by the small diameter portion.

FIGS. 2A and 2B and FIG.
In the cross pattern generation members 41 and 43 shown in (A), the cross-shaped through-hole 42b is a deformed cross having an aspect ratio different from 1: 1. This is because, as described above, in the above embodiment, the optical path diameter adjusting prism 25 is provided in the optical path.
Are provided, and the light images of the cross pattern generating members 41 and 43 are elongated in the lateral direction of the test surface.
Cross-shaped through hole 42 in cross pattern generating member 43
b is previously formed into a deformed cross shape that is long in the direction corresponding to the vertical direction of the surface to be inspected (in FIG. 2A, the horizontal direction of the paper surface), so that the black background 18a of the screen 18 is formed as shown in FIG. Pattern 18 with an aspect ratio of 1: 1
b is formed.

The reason why the pattern formed on the screen 18 is formed in a cross shape as described above is that not only the center position of the pattern but also the rotation of the pattern can be easily specified. It was done. That is, if only the pattern arrangement position on the screen 18 is specified, even if the pattern is circular, the two circular patterns need only be overlapped, so there should be no particular problem.

However, the oblique incidence interferometer has a high sensitivity to a position shift in the height direction of the test surface and a rotational shift (pitching) in the front-rear direction of the test surface, but has a high sensitivity to the lateral shift in the horizontal direction of the test surface. It is characterized by low sensitivity to rotational displacement (rolling), and it has been particularly difficult to adjust the rolling of the test surface only by positioning the two circular patterns. Therefore, focusing on the fact that the pattern rotates when the above-mentioned rolling occurs, a cross shape in which the rotation can be clearly recognized (including the case where the inclination of the horizontal line is different from the vertical line) is adopted as the pattern. It is.

Therefore, any shape that can recognize this rotation is not limited to the one that generates a cross pattern. For example, as shown in FIG. 2B, a cross shape is formed on the light shielding plate 141a. It is also possible to provide a pattern generating member 41a provided with a through hole 42a only at each of the intersections and the vertical and horizontal lines.

On the screen 18 at the subsequent stage, a portion of intermediate brightness may appear around the cross pattern as shown in FIG. 7A due to the influence of the diffracted light. FIG. 2C shows a transmittance distribution in a cross section taken along the line PP of FIG. 2A.
As shown in FIG.
2 is formed so as to have a light transmittance such that it draws a sine curve in the width direction of the slit, thereby reducing the influence of such diffracted light.
8, a clear cross pattern can be observed. Such a through-hole 42 can be obtained, for example, by forming the through-hole 42 with a film having a different density. The light transmittance of the through-hole 42 in the width direction is not limited to that shown in FIG. 2C, and even if only the rising portion, the falling portion, and the shoulder have smooth curves. , The effect of diffracted light can be reduced.

The effect of the diffracted light can be reduced by forming the cross-shaped through holes 42 of the cross pattern generating members 41 and 43 with multiple slits as shown in FIG. As shown in the drawing, the substantially parallel light transmitted through the multiple slits is such that the + 1st-order light of the A light and the -1st-order light of the B light interfere with each other at a position where the optical path lengths of the A light and the B light are equal. A sharp peak of light intensity appears.
By arranging the screen at this position, it becomes difficult for an intermediate brightness portion to appear around the cross pattern, and a clear cross pattern can be observed. Such a multi-slit is not limited to two slits as shown in the figure, but may have three or more slits.

When the alignment of the test surface 2a is adjusted, the cross-shaped pattern on the screen 18 formed by the light beam of the reference light B is formed by the light beam of the measurement light C as described above. Pitch adjustment, rolling adjustment, and height adjustment of the test surface 2a are performed so that the cross patterns on the screen 18 overlap. These adjustments may be manually performed by an operator, but an automatic adjustment system using a computer is preferable in terms of speed and accuracy.

FIG. 4 shows a schematic configuration of an automatic adjustment system for automatically performing each of the above adjustments. This apparatus converts the interference fringe image generated on the screen 50 into a CC image.
The image is taken by the D camera 20, taken into the computer 52 via the image input board 51, and subjected to image analysis by an image calculation means configured as software by a program.

Even at the time of the above-described alignment adjustment of the test surface before the main measurement, the cross pattern is fetched as described above, and the image is analyzed by the image calculation means. At the time of adjusting the alignment of the test surface, the reference light B
The analysis position of the cross pattern on the screen 18 generated by the light beam of the measurement light C is compared with the analysis position of the cross pattern on the screen 18 generated by the light beam of the measurement light C, and the subject is examined so that the latter coincides with the former. 2 is adjusted. That is, based on the difference between the two cross pattern positions compared and analyzed by the computer 52, a predetermined instruction signal for reducing the difference is sent to the motor controller 5
6, a predetermined motor drive current is output from the motor driver 57 in response to the instruction signal, and each of the motors responsible for each adjustment in the test surface posture adjusting means 58 on which the subject 2 is mounted on the stage It is driven by a predetermined amount.

On the other hand, in FIG.
When two cross patterns are generated on the screen 18 by the respective light beams of the measurement light C, it is difficult to identify which of them is the same. Therefore, when the position of the cross pattern is detected, It is necessary to alternately generate cross patterns one by one. Therefore, in the present embodiment, the light-blocking shutters 45 and 46 are provided in the respective optical paths of the reference light B and the measurement light C so that they can be inserted and removed.

That is, when analyzing the position of the cross pattern formed by the luminous flux of the reference light B, the light-shielding shutter 45 is retracted from the optical path of the reference light B, and the light-shielding shutter 46 is inserted into the optical path of the measurement light C. . On the other hand, when analyzing the position of the cross pattern by the light beam of the measurement light C, the light-shielding shutter 45 is inserted into the optical path of the reference light B, and the light-shielding shutter 46 is moved out of the optical path of the measurement light C.

The light-shielding shutters 45, 4
6 and the above-described cross pattern generating member (mask) 41
In the control of the insertion / removal operation of the shutter 52, an instruction signal is output from the shutter & mask controller 53 based on a basic operation program of the computer 52, and a predetermined actuator drive current is output from the driver 54 in response to the instruction signal. , 46 and each of the actuators (55) provided for each of the above-described cross pattern generating members (masks) 41 are each driven by a predetermined amount.

Next, a specific configuration of the above-described inspection surface posture adjusting means will be described with reference to FIGS. FIG. 5 shows a state in which the test surface attitude adjusting means 80 is slid out of the housing through an extraction hole formed in the lower part of the housing panel of the oblique incidence interferometer apparatus 100 and is exposed. This is used when changing a vehicle.

FIG. 6 is a perspective view showing the entire structure of the test surface posture adjusting means 80. The test object 2 taking-out mechanism 104, the height direction adjusting mechanism 103, and the rolling adjusting mechanism 10 are shown.
2. The pitching adjustment mechanism 101 is stacked in this order, and the test surface 2a of the subject 2 is set on the stage 81 of the pitching adjustment mechanism 101.

Here, the pitching adjustment mechanism 101
Has one end rotatably supported by a hinge 84 with respect to a rolling adjustment mechanism 102 located at a lower portion thereof, and the other end thereof has the rolling adjustment mechanism 10.
2 is supported by a coil spring 81a on a cam surface of a rotary eccentric cam 83 attached to the upper surface of the rotary eccentric cam 83.
The stage 81 of the pitching adjustment mechanism 101, which is in contact with the cam surface thereof, is tilted by a desired angle in the pitching direction when the base 3 is rotated by a desired angle, whereby the pitching of the test surface 2a is performed. Adjustments are made.

The rolling adjustment mechanism 102 has substantially the same configuration as that of the pitching adjustment mechanism 101 so that the stage 86 is tilted at a desired angle in the rolling direction, thereby rolling the test surface 2a. Adjustments are made.

In the height direction adjusting mechanism 103, an actuator pin (not shown) protruding from the leg 89 projects vertically by a desired amount in accordance with the rotation of the drive motor. Is configured to move up and down by a desired distance, whereby the height direction of the test surface 2a is adjusted.

Further, the subject 2 extracting mechanism 104 includes a rail 87 mounted on a base 96 and a drive motor 90.
And two belt wheels 91 and 92 and these belt wheels 9
1, a belt 93 is attached to the side of the leg 89 and suspended from the base 92. The legs 89 are slidably engaged with rails formed on both sides of the rail 87 so as to straddle the rail 87. When the drive motor 90 rotates, the belt wheel 91 rotates accordingly, the belt 93 moves, and the leg 89 slides in the longitudinal direction of the rail 87, so that the subject 2 can be moved into and out of the housing. Like that. Further, stopper portions 94 and 95 are provided to keep the moving distance within a predetermined range.

In each of the adjusting units 101 to 104, the output of the drive motor (for example, the motor 82) is output from the tachogenerator (for example, the tachogenerator 85) by the CP.
Feedback to U. As shown in FIG. 7A, the two cross patterns generated by the cross pattern generating member 41 appear as bright patterns 18d and 18e on a dark background on the screen 18c. As described above, an intermediate brightness portion may appear around these cross patterns as described above.

In general, when the surface 2a is roughly adjusted, the two cross patterns 18d and 18e appear in a relatively close state. For example, as shown in FIG. It will be like an overlap. Therefore, for example, the brightness of the cross section taken along the line AA is the difference between the peak and the valley in FIG.
When the image analysis is automatically performed as in (B), it is difficult to determine which of the reference light B and the measurement light C is the cross pattern generated by the light.

Therefore, in this embodiment, each cross pattern is generated one by one on the screen 2 and the position of the cross pattern is analyzed each time, and the cross pattern is referred to on the screen 18 as described above. When generating only the cross pattern 18d by the light B, the light-blocking shutter 46 is inserted in the optical path of the measurement light C, and when generating only the cross pattern 18e by the measurement light C on the screen 18,
The light-blocking shutter 45 is inserted in the optical path of the reference light B. FIG.
8A shows a case where only the cross pattern 18 d is generated by the reference light B, while FIG. 8B shows a case where only the cross pattern 18 e is generated by the measurement light C.

Thus, the two cross patterns 18
When the position information on the screen 18 is obtained for the d and 18e, the computer 52 sets the cross-pattern 18e of the measurement light C to match the cross pattern 18d of the reference light B, Each mechanism 101-
An instruction amount for driving 103 is calculated and output. As a result, the pitching adjustment, the rolling adjustment, and the height adjustment of the test surface 2a are performed, and the two cross patterns 18d and 18e on the screen 18 overlap each other. When the two cross patterns 18d and 18e completely overlap each other, a clear interference fringe 18g is recognized on the screen 18 within the cross pattern 18f in the background 18c as shown in FIG. In FIG. 10,
10 shows a change in stripe intensity on each of the lines a to e in FIG. 9.

In the above-described embodiment, not only the cross pattern 18e by the measuring light C but also the reference light B
Also, a cross pattern 18d is generated on the screen 18. However, since the position of the cross pattern 18d generated by the reference light B does not originally change even when the subject 2 is replaced, information on the position where the cross pattern 18d is to be generated (for example, the center position of the screen 18) ) Is stored in the memory of the computer 52, and the cross pattern 18d by the measuring light C is used.
And the position information is fetched, and the position information is compared with the information of the position where the cross pattern 18d by the reference light B is to be generated stored in the memory. May be controlled. That is, the position information stored in the memory is
When the alignment of the test surface 2a is adjusted to a normal position, it corresponds to positional information of a cross pattern to be generated on the test surface 2a by the measurement light c.

The arrangement of the optical system in this case is shown in FIG. The arrangement of the optical system in the second embodiment is shown in FIG.
However, the cross-pattern generating member 41c is not provided immediately after the collimator lens 14 (common light path for the reference light B / measurement light C) but for the measurement light C immediately before the surface 2a to be measured. The first embodiment is different from the first embodiment in that the light-blocking shutter 45 is disposed only in the optical path of the reference light B in the optical path.
Is different from that of These cross pattern generating members 4
Both the shutter 1c and the light shielding shutter 45 can be inserted into and removed from the optical path.

Next, each operation for adjusting the alignment of the test surface in the second embodiment will be described with reference to the flowchart shown in FIG.

First, the current positions of the stages 81, 86, and 88 of each of the adjustment units 101 to 103 are acquired and stored in the memory (S9). Next, the measurement light C in the preceding stage of the test surface 2a
Insert the cross pattern generating member 41c into the optical path of (S)
10). Next, the light-blocking shutter 45 is inserted into the optical path of the above-described reference light B, thereby preventing the luminous flux of the reference light B from reaching the screen 18 (S11). Next, a cross pattern image of the measurement light c is fetched (S12), and the inspection surface posture adjustment amount calculating means in the computer 52 calculates
The center position of the cross pattern, the length of the vertical line of the cross, the length of the horizontal line of the cross, the inclination of the horizontal line of the cross with respect to the vertical line, and the like are analyzed (S13). The center position of the cross pattern image, particularly the center position of the vertical line, is an important element for pitching adjustment,
The lengths of the upper and lower halves of the vertical line are important factors for height adjustment, and the inclination of the horizontal line to the vertical line is an important factor for rolling adjustment.

The result of analyzing each element in this manner is based on the cross reference (reference light B) stored in the memory regarding the center position, vertical line length, and horizontal line inclination of the cross pattern image.
(S14, S17, S18), and if the result does not substantially match the cross reference, a target position for adjustment is obtained from the difference between the two. (S15) and a step of driving the respective adjustment drive motors to set the target positions and moving the respective stages 81, 86, 88 (S1).
Perform the operation of 6). The operations in steps S12 to S18 are repeatedly performed until the analysis result of each element substantially matches the cross reference.

When the above-mentioned analysis result substantially matches the cross reference, the work of adjusting the posture of the test surface 2a is completed, and the original test surface shape analysis is performed. That is, the light-blocking shutter 45 exits from the optical path of the reference light B, and at the same time, the measurement light C
The cross pattern generating member 41c exits from the optical path of
An interference fringe image of the test surface 2a is formed by the reference light B and the measurement light C. Next, this striped image is taken by the imaging camera 2
0, the fringe image is input into the computer 52 (S20), FFT (data analysis by Fourier transform) of the fringe image is performed (S21), and the result obtained by the analysis is displayed on the image display unit. Is performed (S22).

The oblique incidence interferometer device according to the present invention is not limited to the above-described embodiment, but various modifications can be made. For example, the means for splitting and recombining the light beam from the light source is not limited to the above prism, and each of the conventional light beam splitting and light beam recombining means shown in FIGS. 13 to 15 can be used. It is.

The cross pattern generating member can be arranged closer to the light source than the collimator lens.
It is also possible to generate a straight cross pattern on the imaging surface of the camera.

[0071]

As described above, according to the oblique incidence interferometer of the present invention, the optical path between the light source and the surface to be inspected is
An adjustment pattern generating means for generating an optical pattern whose rotation direction can be determined on the image forming plane is provided, and the reference pattern generated by the reference pattern generating means for providing a position reference of the optical pattern is provided. Compared with the pattern, based on the comparison result, the posture of the test surface is adjusted by the test surface adjusting means so that the two substantially match, so only the pitch adjustment and the height adjustment of the test surface are performed. In addition, the rolling adjustment can be performed well and easily, and the interference fringe analysis in the main measurement can be performed quickly and easily with a simple and compact configuration.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an optical system of an oblique incidence interferometer apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a cross pattern generating unit in the first embodiment shown in FIG.

FIG. 3 is a diagram showing a configuration of a cross pattern generating unit in the first embodiment shown in FIG. 1;

FIG. 4 is a block diagram illustrating a configuration of an oblique incidence interferometer according to a first embodiment of the present invention.

FIG. 5 is a diagram for explaining the movement of the test surface posture adjusting means in the oblique incidence interferometer apparatus according to the first embodiment of the present invention.

FIG. 6 is a diagram showing a configuration of a test surface posture adjusting unit shown in FIG. 5;

FIG. 7 is a view showing a state in which a cross pattern is generated on a screen according to the first embodiment of the present invention;

FIG. 8 is a diagram showing how a cross pattern is generated on a screen according to the first embodiment of the present invention.

FIG. 9 is a view showing a state in which a cross pattern is generated on a screen according to the first embodiment of the present invention.

FIG. 10 is a graph showing a change in stripe intensity on each line shown in FIG. 9;

FIG. 11 is a diagram showing an optical system of an oblique incidence interferometer apparatus according to a second embodiment of the present invention.

FIG. 12 is a flowchart showing the operation of the grazing incidence interferometer according to the second embodiment of the present invention.

FIG. 13 is a diagram showing a configuration of a first conventional oblique incidence interferometer apparatus.

FIG. 14 is a diagram showing a configuration of a second conventional oblique incidence interferometer apparatus.

FIG. 15 is a diagram showing a configuration of a third conventional oblique incidence interferometer apparatus.

FIG. 16 is a diagram showing a configuration of a conventional oblique incidence interferometer apparatus having an alignment adjustment optical path.

FIG. 17 is a diagram showing a light intensity distribution by a double slit.

[Explanation of symbols]

2 object 2a object surface 11, 111, 211, 311 semiconductor laser light source (light source) 12, 312 condenser lens 13, 113, 213, 313 pinhole 14, 114, 214, 314 collimator lens 16 first prism 16a Light beam splitting surface 17 Second prism 17b Light beam combining surface 18, 50, 118, 218, 318, 322 Screen 18a Background 18b Cross pattern 119 Observer 20, 219, 319 TV camera 21, 22, 23, 24, 115, 315 , 320
Mirror 25 Collimating light prisms 41, 41c, 43 Cross pattern generating members 42, 42a, 42b Light transmitting 45, 46 Light shielding shutter 51 Image input board 52 Computer 53, 56 Controller 54, 57 Driver 58, 80 Test surface posture adjusting means 81, 86, 88 Stage 81a Coil spring 82, 90 Drive motor 83 Rotational eccentric cam 84 Hinge 87 Rail 89 Leg 91, 92 Belt wheel 93 Belt 100 Oblique incidence interferometer device 101 Pitching adjustment mechanism 102 Rolling adjustment mechanism 103 Height direction adjusting mechanism 104 Object removing mechanism 116 Parallel plane plate 116a, 216a Reference plane 216 Right angle isosceles triangular prism 216b Incident surface 317a, 317b Diffraction grating 321 Imaging lens A Coherent light beam (collimated light) B coherent light beam (reference light) C coherent light beam (measurement light)

Continuation of the front page (72) Inventor ▲ Kuzu ▼ Souto 1-324 Uetake-cho, Omiya City, Saitama Prefecture Inside Fuji Photo Equipment Co., Ltd. (72) Fumio Kobayashi 1-324, Uetake-cho, Omiya City, Saitama Prefecture Fuji Photo F term in Koki Co., Ltd. (reference)

Claims (10)

[Claims] 1. A collimated coherent light is split by a light beam splitting means, one light beam is used as reference light, and the other light beam is obliquely incident on a surface to be measured as measurement light. The oblique incidence interferometer device configured to combine the measurement lights reflected from the inspection surface in a light beam combining unit and cause them to interfere with each other, and to form a generated interference fringe on an interference fringe observation imaging surface, An adjustment pattern generation unit that is arranged in an optical path between a light source that generates light and the surface to be inspected and generates an optical pattern that can determine a rotation direction on the imaging surface; A reference pattern generating means for generating a reference pattern consisting of an optical pattern or an electrical pattern capable of determining a rotation direction to be a position reference, and an optical pattern generated by the adjustment pattern generating means An oblique incidence interferometer apparatus comprising: a test surface attitude adjusting means for adjusting an arrangement attitude of the test surface so that the pattern substantially matches the reference pattern. 2. The oblique incidence interferometer according to claim 1, wherein said adjustment pattern generating means is removably inserted in an optical path between said light beam dividing means and said surface to be inspected. apparatus. 3. The reference pattern generating means and the adjustment pattern generating means are also used, and a through hole of a predetermined shape is provided between the light source and the light beam dividing means so as to be freely inserted and removed. 2. The oblique incidence interferometer according to claim 1, wherein the oblique incidence interferometer comprises a member. 4. The oblique incidence interferometer apparatus according to claim 3, wherein said member is arranged so as to be freely inserted into and removed from a parallel light beam. 5. The oblique incidence interferometer apparatus according to claim 1, wherein said adjustment pattern generating means is a light shielding plate provided with a cross-shaped through hole. 6. The reference pattern generation unit generates position data of an optical pattern on the image plane generated by the adjustment pattern generation unit when the test surface is arranged at a regular measurement position. 6. The grazing incidence interferometer device according to claim 1, wherein the oblique incidence interferometer device is a stored memory. 7. The method according to claim 7, wherein the position data of the optical pattern is obtained based on the optical pattern generated on the image plane by the reference pattern generating means arranged in the reference light. 7. The oblique incidence interferometer device according to claim 6, wherein: 8. The oblique incidence according to claim 1, wherein a light-blocking shutter is provided in the optical path of the reference light and / or the optical path of the measurement light so as to be freely inserted and removed. Interferometer device. 9. The test surface attitude adjusting means uses a rotation axis orthogonal to the test light incident surface of the test surface and included in the test surface, with respect to the test light incident surface. Pitching adjustment for adjusting the rotation of the test surface, rolling adjustment orthogonal to the rotation axis, and performing rotation adjustment of the test surface using a rotation axis included in the test surface, and vertical adjustment of the test surface. The oblique incidence interferometer device according to any one of claims 1 to 8, wherein the oblique incidence interferometer device is configured to perform at least each of height adjustments for performing the adjustment. 10. The method for adjusting the posture of the surface to be inspected includes an imaging unit that captures an image formed on the image plane, a posture adjustment amount calculation unit for the surface to be inspected disposed in a computer, and the operation unit. 10. The oblique method according to claim 1, wherein the control is performed using an automatic control unit including an actuator that drives the test surface posture adjusting unit based on the adjustment amount calculated by the control unit. Incident interferometer device.