JP3230989B2 - Object positioning device for light wave interference device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an object positioning device for an optical interference device, and more particularly to a device for measuring the surface shape of a test surface of a thin plate-shaped object using light having a short coherence distance. The present invention relates to an object positioning device of an optical interference device used when positioning a test surface within an interference possible range.

[0002]

2. Description of the Related Art For example, in a Michelson-type interferometer, coherent parallel light is split into a reference light and a test light by a light splitting means, and the reference light and the test light are divided into a reference surface and a test light. After being reflected on the surface to be inspected and recombined by the light splitting means, interference fringes are formed on the observation surface. By observing the interference fringes, the shape of the unevenness of the surface to be evaluated is evaluated. Can be done.

When a laser interferometer is used as the interferometer, it is not necessary to accurately set the position of the test surface with respect to the reference surface because the interference distance of the laser light is long. In addition, the reflected light from the back surface of the subject also interferes with the reflected light from the test surface and the reflected light from the reference surface, and the interference fringe of the noise component is superimposed on the original interference fringe. For this reason, conventionally, when measuring thin glass or the like using a laser interferometer, it has been necessary to take measures such as applying a refractive index matching oil to the back surface where ghosting occurs.

[0004]

However, taking such measures requires a great deal of trouble, and there is a problem that the subject is contaminated. In addition, particularly when the thickness of the test object is extremely thin, if the matching oil or the like is applied to the back surface, the test object is distorted due to the influence of the surface tension, and a problem that accurate measurement of the test surface cannot be performed occurs.

Therefore, when measuring the surface shape of a thin glass plate or the like, light having a short coherence distance (light having a coherence distance shorter than twice the thickness t of the subject) is used as the measurement light and the surface to be measured is measured. It is conceivable to set only the interference possible range. However, in the above prior art, if the coherent distance of the light from the light source is S _CL , the range L of the interfering test surface where the test surface is to be disposed is L <S _CL / 2.

For example, when a light source having a coherence distance of about 30 μm such as a red light emitting diode (LED) is used as a light source, the interference possible range L is shorter than 15 μm. Unless the test surface of the subject is positioned within this narrow range, no interference fringe indicating the relative shape to the reference plate is generated. The present invention has been made in view of the above circumstances, and provides a subject positioning apparatus for a light wave interference apparatus that can easily set a test surface within an interference possible range in a light wave interference apparatus using light having a short coherence distance. It is intended for.

[0007]

In order to achieve the above object, the object positioning apparatus of the light wave interference apparatus according to the present invention has a light coherence length that is shorter than twice the thickness of the object. Splits the light from the light source into two systems, irradiates one on the test surface of the subject and the other on the reference surface, the test light from the test surface and the reference light from the reference surface. In a light wave interference apparatus for observing interference fringes generated by interference of light and measuring the surface shape of the test surface based on the observation result, an optical path between the light splitting position and the position of the test target surface where interference is possible is provided. At least one having a focal position within the interference range position
An object positioning device for an optical interference device, in which two condensing lenses are arranged and the object surface can be positioned in the interference possible range, while holding a mounting table on which the object is mounted, A predetermined position is fixed to a fixed machine frame of the subject position adjustment mechanism for adjusting the movement of the subject in a direction orthogonal to the test surface and the posture of the test surface, or a portion fixed in position relative to the fixed machine frame. At least three spaced apart
Two reference planes, a lens holding unit that holds the condenser lens, and the reference surfaces,
And a lens position adjusting means having a height adjusting portion for adjusting the height with respect to each of the reference planes. Further, it is preferable that the lens position adjusting means is provided with an opening for permitting passage of a light beam for light wave interference on the test surface in a state set to position the test surface.

In a state where the lens position adjusting means is set so as to position the test surface, one of the condenser lenses is held at a position facing a central portion of the test surface. It may be. Further, in a state where the lens position adjusting means is set to perform the positioning of the test surface, the condenser lens is held at at least three predetermined positions facing the test surface. Is also good.

In addition, a mark for recognizing the correspondence between the reference plane and the height adjustment unit is displayed at a visible position, or the lens position adjustment unit holds the height adjustment unit. Arms are arranged radially, and the angular interval between adjacent arms is at least 1
It is desirable that the configuration be set so as to be different from the other angular intervals at the various places, so that the correspondence between each reference plane and each adjustment means can be understood at a glance.

Further, the at least three predetermined positions are three vertex positions of a right-angled triangle, and one of two sides sandwiching the right-angle of the right-angled triangle gives an inclination to a surface to be inspected of the object position adjusting mechanism. It is desirable that one of the two orthogonal axes and the other of the two sides be disposed so that their directions coincide with the other of the two orthogonal axes.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram for explaining a light wave interference device which is a premise of a subject positioning device of the present invention, and is configured as a Michelson type. This Michelson-type interferometer comprises a light source 1,
A collimator lens 2, a beam splitter 3, a reference plate 4, an imaging lens 7, and a CCD element 8,
The subject positioning apparatus according to the present invention (see FIGS. 4 and 5) can move and adjust the position of the subject 5 while holding the subject 5.

The light source 1 is a light source that emits light having a short coherent distance. The light 1a emitted from the light source 1 is collimated by a collimator lens 2 and then collimated by a beam splitter 3 with a reference light. It is divided into analysis and analysis.
Then, the reference light and the test light are reflected by the reference surface 4a of the reference plate 4 and the test surface 5a of the test object 5 supported by the test subject positioning device, respectively, and then combined again by the beam splitter 3 to form an imaging lens. 7, so as to form interference fringes on the image plane of the CCD 8.

In this interference apparatus, the back surface 5b of the subject 5 is placed on the interference fringe formed by the reflected light from the surface 5a of the subject 5 and the reflected light from the reference surface 4a of the reference plate 4. A light source that emits light 1a having an extremely short interference distance is selected as the light source 1 so that interference fringe noise based on reflected light from the light source is not superimposed. When the light source that emits light with a short coherence distance is used in the interference device, the position of the test surface 5a in the optical axis direction is adjusted so that the optical path lengths of the reference light and the test light are equal to each other. It is necessary to adjust the distance of the test surface.

As shown in FIG. 1, if the coherent distance of the light 1a is S _CL , then L <S
_CL / 2. Moreover, the coherent distance _SCL is set to be extremely smaller than the thickness t of the subject 5.
For example, the light source 1 is set to a red L having a coherent distance S _CL ≒ 30 μm.
In the case of ED, the possible interference range L is a value smaller than 15 μm. Thereby, when the interference fringe based on the test surface 5a of the subject 5 is observed during the measurement of the interference fringe, the interference fringe based on the back surface 5b of the subject 5 is not observed.

Then, the subject 5 is moved in the direction of arrow A by the subject positioning device as shown in FIGS. 4 and 5, and the test surface 5a is positioned within the interference possible range. Thus, it is not easy to position the test surface 5a of the test object 5 within the extremely short range 6. In particular, when the interference fringes formed on the CCD 8 are observed on the monitor and the above-described positioning is performed by stopping the movement of the subject at the moment when the interference fringes appear, when the interference fringes appear on the monitor, Since the interference fringes also move at high speed in accordance with the movement of the surface 5a to be inspected, it is extremely difficult to confirm the appearance of the interference fringes.

Therefore, in the subject positioning apparatus according to the present invention, as shown in the figure, a condensing lens 9 having a focal position F within the interference possible range 6 for positioning the subject is provided in the optical path. It is arranged.

The operation and effect of the object positioning device using the condenser lens 9 will be described below with reference to FIGS. First, FIG. 2A shows that the test surface 5a of the test object 5 does not reach the coherent range 6 and the light from the condenser lens 9 is radiated and reflected on the test surface 5a in a divergent state. Show the case.

The condenser lens 9 is arranged in a parallel light beam emitted from the beam splitter 3 shown in FIG.
The test surface 5 is located at a position farther than the focal position F of the condenser lens 9.
When a exists, the light beam that has passed through the condenser lens 9 irradiates the surface 5a to be detected and is reflected, but the reflected light beam is located at a position F symmetrical to F with the surface 5a interposed therebetween. ′
It proceeds as if the light emitting point is present. When this light beam passes through the condenser lens 9 again, as shown in FIG. 2A, the light beam returns to the beam splitter 3 as a converged light instead of a parallel light.

FIG. 2B shows that the surface 5a to be detected is
Shows a case where the focus position F has just been reached. In this case, the light beam reflected by the test surface 5a becomes a light beam having the focal point F as a light emitting point, and this light beam is again converted into a parallel light beam by the condenser lens 9 and returns to the beam splitter 3.

FIG. 2C shows that the surface 5a to be detected is
Is shown after passing through the focal position F. In this case, a position F 'symmetrical to the focal point position F with the test surface 5a interposed therebetween becomes an actual point light source, and a divergent light beam from this point light source reenters the condenser lens 9. This position F '
Is emitted from the condenser lens 9 because it falls inside the focal position F of the condenser lens 9, and the backward luminous flux becomes divergent light and returns to the beam splitter 3.

In each of the cases shown in FIGS. 2A, 2B and 2C, the pattern formed on the CCD 8 is shown in FIG.
(B) and (c) are displayed. That is, FIG.
In the state shown in FIG. 3A, as shown in FIG. 3A, a dark spot 322b is formed at the portion of the diameter 321 of the condensing lens 9, and a smaller and brighter spot is formed in the spot 322b. A spot 322a is formed.

In the state shown in FIG. 2B, as shown in FIG. 3B, the entire size portion 321 of the diameter of the condenser lens 9 becomes a spot 323 of uniform brightness. The brightness is about the same as that around the portion 321. Further, in the state shown in FIG.
As shown in (c), a slightly bright spot 325 is formed in a range larger than the size portion 321 of the diameter of the condenser lens 9. A dark spot 324 is formed corresponding to the size 321 of the diameter of the condenser lens 9.

As described above, the luminous flux traveling backward through the condenser lens 9 forms a spot of a predetermined size or a predetermined brightness on the CCD 8, and the spot 323 and the visual field 320 are formed as shown in FIG. When the brightness is hardly distinguished from other areas in the area, it is possible to detect that the test surface 5a is positioned near the interference possible range 6.

In order to make the positioning more accurate, the sensitivity to the change in brightness or the change in spot size may be increased. For this purpose, as is clear from FIG. 2, it is desirable that the converging angle of the light beam emitted from the beam splitter 3 by the converging lens 9 is larger. That is, a lens whose distance to the focal position F is smaller than the diameter of the condenser lens 9, in other words, the diameter of the condenser lens 9 is D, and the distance to the focal position F (focal length) is When f is set, the smaller the f / D is, the better the sensitivity is. Here, f / D is the numerical aperture (F number) of the lens, and the smaller the F number, the brighter the lens.

An object positioning device according to an embodiment of the present invention, which is mounted on the light wave interference device, will be described below with reference to FIGS. Here, FIG. 4 (A) is a plan view showing the object positioning device according to the present embodiment, FIG. 4 (B) is a front view thereof, FIG. 5 is a side view thereof, and FIG. 4 (B) and FIG. Some of them are shown broken.

That is, the subject positioning apparatus 11 holds the condensing lens 9 and adjusts the position of the condensing lens 9, a lens position adjusting section, the subject 5, and the subject 5 And a subject position adjustment part for performing vertical movement and posture adjustment of the subject. The subject positioning device of the present invention may be constituted only by the lens position adjusting portion, and the subject position adjusting portion may be a separate device.

4 and 5, first, the subject position adjusting portion includes a base 21, a fixed machine frame 22 fixed on the base 21, and a Z accommodated in the fixed machine frame 22. Axis adjustment stage 23 and two-axis tilt adjustment stage 24
And a subject mounting table 26 on which the subject 5 is mounted. Further, the two-axis tilt adjustment stage 24 is configured to be mounted on the Z-axis adjustment stage 23, and the subject mounting table 26 is further mounted on the two-axis tilt adjustment stage 24. An adjustment micrometer 23A for the Z-axis adjustment stage 23 and adjustment micrometers 24A and 24B for the two-axis tilt adjustment stage 24 protrude from the side wall of the fixed machine frame 22 in a direction orthogonal to each other.

On the other hand, the lens position adjusting portion includes three driving screws 30A having a flat surface portion (reference surface) which are driven into the upper surface portion of the fixing machine frame 22 at a predetermined interval from each other, and radially. A lens holding plate 28 having three extending arm portions and holding the condenser lens 9 at a central portion thereof, and a tip portion of each arm portion of the lens holding plate 28 screwed into the tip portion, Three height adjusting screws 29A, B, which are arranged so as to be applied to the screw head flat surfaces of the corresponding driving screws 30A, that is, the reference surfaces.
C (see FIG. 6).

In a state where each of the adjusting screws 29A, B and C is applied to the corresponding reference plane (the state shown in FIGS. 4 and 5), the condenser lens 9 is disposed at a position facing the subject 5. It will be. In the present embodiment, since the external size of the object mounting table 26 is larger than the external size of the lens holding plate 28, height adjustment screws 29A, B, 3 as a relief hole for C
Two through holes 26A are formed.

Next, the operation of each of the above parts will be described. As shown in FIG. 4 (b), the Z-axis adjustment stage 23 of the subject position adjustment part has an adjustment micrometer 23A.
When the coarse and fine adjustments are independently adjusted by the inner knob and the outer knob, respectively, the head pin 23 is rotated.
B advances and retreats in the axial direction, and the cam 23C which is in contact with this rotates around the rotation shaft 23D.

The cam 23C has two projecting portions orthogonal to each other. One projecting portion contacts the head pin 23B of the micrometer 23A, and the other projecting portion contacts the lower surface of the stage plate 23F. It is in contact with the lower end of the provided drive pin 23E. Thus, the rotation of the cam 23C causes the drive pin 23E to move up and down, and accordingly, the stage plate 23F moves up and down.

The stage plate 23F is connected to the base 23H of the Z-axis adjustment stage 23 by a plurality of screw portions 23G.
These screw portions 23G are urged downward inside the base portion 23H such that the lower end of the drive pin 23E reliably contacts the other protruding portion of the cam 23C. ing. The Z-axis adjustment stage 23
The base 24C of the stage plate 24F of the two-axis tilt adjustment stage 24 is mounted on the stage plate 23F. The two-axis tilt adjustment stage 24 moves up and down in accordance with the vertical movement of the stage plate 23F. It has become.

Next, the two-axis tilt adjustment stage 24
7, micrometers 24A and B for adjusting the inclination of each axis, two drive pins 24D and I disposed between the base 24C and the stage plate 24F, and a fulcrum position. Is provided. That is, the head 24K of the micrometer 24B advances and retreats in accordance with the rotation of the one micrometer 24B, and the obliquely cut end face of the head 24K and the drive which is also obliquely cut in response to the advance and retreat. The lower end surfaces of the pins 24D slide with each other, and the drive pins 24D move up and down,
The stage 24F is provided with a tilt in a linear direction (Y-axis direction) connecting the support ball 24E and the drive pin 24D with the position where the support ball 24E is provided as a fulcrum.

The rotation of the other micrometer 24A also causes the drive pin 24I to move up and down as in the case of the operation of the micrometer 24B, and the stage plate 24
F has a tilt in the linear direction (X-axis direction) connecting the support ball 24E and the drive pin 24I with the arrangement position of the support ball 24E as a fulcrum.

A fitting groove for fitting the support ball 24E is formed on the upper surface of the base 24C and the lower surface of the stage plate 24F at a position facing the support ball 24E. Also, a line (X, X) connecting the position where the support ball 24E is disposed and the position where the two drive pins 24D and I are disposed.
In the vicinity of (on the Y axis), a total of four screw portions 24G for connecting the stage plate 24F and the base portion 24C are provided. The screw portion 24G is provided so that the support ball 24E is securely fitted to the groove portion, and the two drive pins 24D and I are connected to the lower end surface of the stage plate 24F and the micrometer 24.
It is configured to be urged downward inside the base portion 24C so as to reliably contact the head portions 24K of A and B.

The stage plate 24F has a central hole 5
1, and a plurality of through holes (not shown) are formed to reduce the weight of the entire apparatus. As shown, a subject mounting plate 26 is mounted on the two-axis tilt adjustment stage 24F. Therefore, the subject mounting plate 26 is mounted on both the Z-axis adjustment stage 23 and the two-axis tilt adjustment stage 24.
The shaft tilt adjustment stage 24 performs the tilt adjustment in two axial directions orthogonal to the vertical direction.

Next, the lens position adjusting portion will be described. This lens position adjustment part, as described above,
The upper flat surfaces of the screw heads of the three driving screws 30A and 30B driven into the upper surface portion of the fixing machine frame 22 in the subject position adjustment portion are positioned at the heights held by the three arms of the lens holding plate 28 with respect to the reference plane. The adjusting lenses 29A, 29B and 29C are applied, and the condenser lens 9 held at the center of the lens holding plate 28 is arranged at a position facing the subject 5.

The driving screws 30A and 30B are made of stainless steel, and have a higher hardness than aluminum which is a constituent material of the fixing machine frame 22.
Even when 9A, B, and C are repeatedly applied, the strength is high with respect to the impact or load.

The height adjusting screw 29A is driven into the screw 3
FIG. 6 shows a state where the reference surface of 0A is applied. The height adjusting screw 29A is screwed to the lens holding plate 28 by the screw portion 41, and by rotating the screw 29A, one of the lens holding plate 28 is rotated.
The two arms can move up and down. Such a configuration is the same for the other height adjusting screws 29B and C, and accordingly, these three screws 29B
By adjusting the rotation direction and the rotation amount of A, B, and C, the inclination of the lens holding plate 28 can be freely adjusted.

Actually, these height adjusting screws 29
The adjustment of the inclination of the lens holding plate 28 by the rotation operation of A, B, and C is performed only in the initial state, and once the adjustment of the inclination is completed, the screws 29A, B, and C are attached to the lens holding plate 2
8 is fixed by an adhesive or the like. By performing such adjustment in the initial state, the screw 29A,
It is possible to prevent a decrease in measurement accuracy due to a dimensional error in B and C. In the height adjusting screws 29A, 29B, and 29C, as shown in FIG.
A coil spring 42 is attached to a portion between the upper surface portion 8 and the upper portion 8 so as to reduce backlash in the screw operation.

The lens holding plate 28 is provided as shown in FIG.
As shown in (a), three arms are formed to extend radially from the center, and the subject 5 can be seen from a portion (opening) 33 between the arms. I have. That is, by adjusting the height and the inclination of the surface 5a to be inspected by the object position adjustment portion, as shown in FIG. 3B, the brightness of the spot 323 and the other region in the visual field 320 are hardly distinguished. When there is no state, it is detected that the test surface 5 a is positioned in the vicinity of the interference possible range 6. At this time, the position of the test object 5 observed from the opening 33 is detected. , An interference fringe representing the surface shape of the test surface 5a appears.

Accordingly, the operator recognizes that the test surface 5a is set at the position of the interference possible range based on the size and brightness of the spot formed by the condenser lens 9, and also observes the object observed through the opening 33. It can be confirmed that the interference fringe on the sample 5 has reliably set the position in the interference possible range.

Further, the lens holding plate 28
In the case where the shape does not greatly differ, the same one can be used as it is. In this case, each time the subject 5 is replaced, each height adjusting screw 29A,
It is necessary to set B and C on the corresponding reference planes. In this case, for at least one pair, as shown in FIG. 4A, for example, as shown in FIG. 4A, the arm portion and the base 21 are arranged so that the correspondence between the height adjusting screws 29A, B, and C and the reference surface can be understood at a glance. If the marks 34A and 34B are attached to the respective predetermined positions, it is unnecessary to confirm the set position each time the lens holding plate 28 is set.

Also, as in the device 111 shown in FIG. 8, the angular interval α of one portion is changed from the angular interval of another portion without making the angular interval of each arm of the lens holding plate 128 uniform. So that the height adjustment screws 29A, B,
Even if C and the reference plane are arranged at corresponding positions, the setting operation of the lens holding plate 128 can be facilitated.

It should be noted that the object positioning device of the light wave interference device of the present invention is not limited to the above-described embodiment, but may be modified in various forms. For example, the shape of the lens holding portion is not limited to that of the above embodiment, and four or more arm portions may be radially arranged. For example, the arm portions may be combined in a triangle, or a donut shape may be used. It may be. The point is that the shape may be a shape that can hold the height adjusting screw and the condenser lens that are arranged at a certain distance from each other, and a shape that has an open portion that allows the subject to be observed.

Further, the number and arrangement position of the condenser lenses 9 are not limited to those in the above embodiment, but may be two or more or positions other than the central portion.
The number and arrangement position can be as shown in FIG.
The device 211 shown in FIG. 9 includes a focusing lens at each of the arm portions of the lens holding plate 228 at an intermediate position between the central portion and the positions of the height adjusting screws 229A, B, and C at the tip of each arm portion. 227A, B and C are arranged and held.

As described above, by arranging and holding the condenser lenses 227A, 227B, 227C at positions away from the central portion,
For example, when the subject is an optical disc or the like having a hole in the center, the subject can be positioned with respect to the subject.
By arranging and holding the plurality of condenser lenses 227A, 227B, 227C, a more accurate subject positioning operation can be performed.

Further, as in the device 311 shown in FIG. 10, the extending direction of the arm portions 328A and 328B of the lens holding plate 328 is changed by the micrometer 24A and the micrometer 24A.
X axis 124A and Y axis 124B adjusted by B
And the condenser lens 327A is attached to the arm section 328A, and the condenser lens 327B is attached to the arm section 328B.
And the condenser lens 327C is disposed at the intersection of the arm 328A and the arm 328B. In this device 311, reference numerals 329 A, B, and C denote height adjusting screws, of which 329 C is a condenser lens 327.
Ideally, it is provided at the same position as C. However, as shown in the figure, it is near the condenser lens 327C, and is one for each of the arm portions 328A and 328B.
If it is provided at a position at an angular interval of 35 degrees, an ideal state is approximated.

With this configuration, the adjustment of the Z axis can be adjusted by the condenser lens 327C, the adjustment amount of the inclination adjustment of one of the X axis and the Y axis, and the size of the spot by the condenser lens. Since the change in brightness can be made to correspond one-to-one, vertical movement and tilt adjustment of the subject are facilitated.

The three condenser lenses 327A,
When adjusting the mutual height (position in the optical axis direction) of B and C, for example, first, the condenser lens 327C is positioned, and then the condenser lens 327A and the condenser lens 327B are moved with respect to the condenser lens 327C. It is desirable to adjust, but in this case, the condenser lens 327A and the condenser lens 327 are attached to the lens barrel which is screwed when attached to the arm portion.
B, and by attaching this lens barrel to the arm portion, the condenser lens 327A and the condenser lens 32
7B can be easily moved up and down with respect to the arm portion, and the mutual height adjustment of these three condenser lenses 327A, 327B, and 300C becomes easy.

In the above-described embodiment, the lens holding plate 28 is manually set. However, the lens holding plate 28 is, of course, determined based on a signal that can recognize the difference between positioning and interference fringe measurement. Can be automatically inserted into and retracted from the parallel light beam. Further, based on the spot patterns as shown in FIGS. 3A, 3B and 3C, the CPU (not shown) automatically determines whether or not the current state is the state where the current position is positioned at a predetermined position. Judge, and control the above-described subject position adjustment part based on the judgment result,
The subject may be stopped and positioned at a predetermined position.

Further, as shown in FIG. 1, the shielding plate 10 is moved in the direction of arrow B so that it can be inserted and retracted in the optical path of the reference light, and the reference light is prevented from entering the reference plate 4 during the above-described positioning. By doing so, the S / N of the spot pattern in the observation visual field 320 is improved, and a more accurate positioning operation can be performed. Further, in the above embodiment, the reference plane is provided on the fixed machine frame of the subject position adjusting portion, but may be provided on a portion which does not relatively move with respect to the fixed machine frame.

Further, as the light receiving element, not only a surface sensor such as the above-described CCD but also a line sensor or a single element sensor can be used. The device of the present invention is not limited to a Michelson-type interferometer, and can be applied to an interferometer capable of making the optical path lengths of the test light and the reference light approximately equal distances, for example, a Mach-Zehnder interferometer. is there.

[0054]

As described above, according to the apparatus of the present invention, the light source for emitting light having a very short coherence distance is provided,
A condensing lens having a focal position within an interference possible range of the surface to be detected is provided in an optical path of a light beam from the beam splitter. Thus, when the test surface is positioned within the interference possible range, the light beam from the condenser lens is reflected so as to be substantially focused on the test surface, and is again converted into a substantially parallel light beam by the condenser lens. Since the light beam is incident on the light receiving element, the state of the light beam incident on the light receiving element when the surface to be detected is not within the interference possible range (divergent light beam or converged light beam) is different.

Therefore, the spot shape to be observed greatly differs depending on whether or not the test surface is set in the interference possible range, and the current setting position of the test surface can be clearly recognized. This makes it possible to easily position the test surface.

Also, at least three reference surfaces for setting the condenser lens on a fixed machine frame that is not linked to the movable portion for adjusting the position of the subject or a portion fixed in position relative to the fixed machine frame. And a height for adjusting the height of the lens holder corresponding to each of the three reference planes with respect to each of the three reference planes with respect to each of the three reference planes. A lens position adjusting unit having an adjusting unit is provided, and by adjusting each of these height adjusting units, the inclination of the lens holding unit can be satisfactorily adjusted. Accordingly, even when the test surface is set within an extremely short interference possible range, the positioning operation of the test object can be performed extremely smoothly irrespective of a manufacturing error of each part of the lens position adjusting means.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining an outline of an object positioning device of an optical interference device according to the present invention.

FIG. 2 shows the operation of the device shown in FIG.

FIG. 3 is a view showing the operation and effect of the device shown in FIG. 1;

FIG. 4 is a schematic view showing an embodiment of the apparatus of the present invention ((a) is a plan view, (b) is a front view).

FIG. 5 is a schematic diagram (side view) showing an embodiment of the apparatus of the present invention.

FIG. 6 is an enlarged view showing a part of the apparatus shown in FIG. 4;

7 is an enlarged view of a part of the apparatus shown in FIG. 4 ((a) is a plan view, (b) is a front view)

FIG. 8 is a diagram showing a partially modified example of the device shown in FIG. 4;

FIG. 9 is a diagram showing a partially modified example of the device shown in FIG. 4;

FIG. 10 is a diagram showing a partially modified example of the device shown in FIG. 4;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Light source 2 Collimator lens 3 Beam splitter 4 Reference plate 4a Reference surface 5 Subject 5a Test surface 6 Interferable range 7 Imaging lens 8 CCD 9, 127, 227A, 227B, 227C, 327A, 327B, 327C Condensing lens 11, 111, 211, 311 Object positioning device 22 Fixed machine frame 23 Z-axis adjustment stage 23A, 24A, 24B Micrometer 24 2-axis tilt adjustment stage 26 Object mounting table 28, 128, 228, 328 Lens holding plate 328A, 328B Arm part 29A, 29B, 29C, 129A, 129B, 129
C, 229A, 229B, 229C, 329A, 329
B, 329C Height adjusting screw 30A, 30B Driving screw 33 Open part

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) G01B 9/00-11/30 102 G01M 11/00-11/08

Claims (7)

(57) [Claims] 1. A method according to claim 1, wherein the light from the light source whose coherence distance is shorter than twice the thickness of the subject is divided into two systems.
Irradiating one on the test surface of the subject and the other on the reference surface,
In a light wave interference apparatus for observing interference fringes generated by interference between the test light from the test surface and the reference light from the reference surface, and measuring the surface shape of the test surface based on the observation result, At least one condensing lens having a focal position within the interference-possible range position is arranged in an optical path between the division position and the interference-possible range position of the test surface, and the test surface is set at the interference-possible range. What is claimed is: 1. An object positioning apparatus for an optical interference device, comprising: a moving unit that moves a subject in a direction perpendicular to a surface to be examined and a posture of the surface while holding a mounting table on which the object is placed; At least three reference planes provided at predetermined intervals on a fixed machine frame of the subject position adjusting mechanism for adjusting the distance, or on a portion fixed in position relative to the fixed machine frame, and the condenser lens Lens holding unit for holding the A lens position adjusting means having a height adjusting portion for adjusting the height of the lens holding portion with respect to each of the reference surfaces in contact with each of the reference surfaces; Positioning device. 2. The apparatus according to claim 1, wherein said lens position adjusting means is provided with an opening for permitting passage of a light beam for light wave interference on said test surface in a state set to perform positioning of said test surface. The subject positioning apparatus of the light wave interference apparatus according to claim 1, wherein: 3. A state in which the lens position adjusting means is set so as to position the test surface, and holds one of the condenser lenses at a position facing a central portion of the test surface. The object positioning device for a light wave interference device according to claim 1 or 2, wherein: 4. In a state in which the lens position adjusting means is set to perform positioning of the test surface, the condenser lens is held at at least three predetermined positions facing the test surface. The object positioning apparatus for an optical interference device according to claim 1, wherein: 5. The mark according to claim 1, wherein a mark for recognizing a correspondence between the reference plane and the height adjustment section is displayed at a position where the mark can be visually recognized. An object positioning device for an optical interference device. 6. The lens position adjusting means has a shape in which arm portions respectively holding the height adjusting portions are radially arranged, and an angular interval between adjacent arm portions is different from another angular interval at at least one position. The subject positioning apparatus of the light wave interference apparatus according to any one of claims 1 to 4, wherein the apparatus is set differently. 7. The at least three predetermined positions are three vertex positions of a right-angled triangle, and one of two sides sandwiching the right-angled angle of the right-angled triangle is inclined with respect to the test surface of the subject position adjustment mechanism. 7. An apparatus according to claim 4, wherein one of the given two orthogonal axes and the other of the two sides are arranged so that their directions coincide with the other of the two orthogonal axes. An object positioning device for the light wave interference device according to the above.