JPH09305094A - Telecentric optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrict a light passing area in a telecentric optical system without lowering of the light utilization efficiency and the numerical aperture of a light receiving system by performing exposure with which hologram reproduced light is reproduced from the partial area of a hologram. SOLUTION: When reference light is made incident on the hologram 3 from a light source 8 through lenses 9 and 10, the light equivalent to a situation that a point light source exists in the aperture of a pinhole 1 is reproduced by the hologram 3. The reproduced light is formed into an image on an object 6 by a telecentric lens 2b. The hologram 3 is disposed nearly at the positions of the pupils of the telecentric lenses 2a and 2b, and the exposure which makes the hologram 3 function as an exposure mask for restricting the optical area of the projected light is performed to the hologram 3. Therefore, in the case the hologram 3 is used, the received light is made to pass by using all the surface of the hologram and the efficiency of the received light is remarkably improved though the projected light is generated from the partial area of the surface of the hologram.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a telecentric optical device which realizes a spatial filter arranged between telecentric optical systems by using a hologram.

[0002]

2. Description of the Related Art Techniques for measuring the shape of an object include, for example, Japanese Patent Laid-Open No. 4-265.
As shown in Japanese Patent No. 918, etc., there is a system in which confocal optical systems are two-dimensionally arranged, and FIG. 13 shows the configuration thereof.

In FIG. 13, the light from the light source 100 becomes parallel light through the lenses 101 and 102 and is incident on the pinhole array PH1. The pinhole array PH1 has pinholes arranged in a matrix. The light that has passed through the pinhole array PH1 passes through the half mirror 103, is condensed by the telecentric lenses 105a and 105b having a light shielding mask (aperture stop) 104, and is projected onto the measured object 106. Object to be measured 106
Are mounted on a moving stage 107 that can be displaced in the Z-axis direction. The light reflected by the measured object 106 is the lens 1
The light is collected by 05a and 105b, reflected by the half mirror 103, and imaged at a position conjugate with the pinhole array PH1. A pinhole array PH2 is arranged at this image forming position,
The light passing through the pinhole is detected by each photodetector of the photodetector array 108.

According to such a conventional configuration, the moving stage 1
While displacing 07 in the Z direction, the individual outputs of the photodetectors 108 are separately sampled, and the Z direction position when the output of each photodetector is maximized is detected as the surface position of the object 106. You can

By the way, in such a conventional structure, the light shielding mask 104 is arranged at the pupil position between the telecentric lenses 105a and 105b, and the light shielding mask 104 is provided.
The light passing region is limited by the above, and the effect of reducing the diameter of the spot light focused on the measured object 106 (improving the resolution) is obtained.

In this specification, the pupil position means the position in FIG.
As shown in FIG. 4, one of the telecentric lenses 105
a and the other telecentric lens 105b, the focal length f2 of one lens 105a and the other lens 105b
And a total distance (f1 + f2) from the focal length f1 of the lens, and the focal length f2 from one lens 105a (the focal length f1 from the other lens 105b).
Defined as separated positions.

However, in such a conventional device, a light-shielding mask in which an aperture is actually formed, which allows light to pass through in a part thereof and blocks light in the other part, allows passage of light at the pupil position. Since the area is limited, the light projecting characteristic is improved, but the light receiving characteristic may be adversely affected. That is, in the conventional device, when the light is received, the light is blocked by the light-shielding region of the light-shielding mask, so that the utilization efficiency of the received light is reduced and the numerical aperture of the light-receiving optical system is reduced.

The present invention has been made in view of the above circumstances, and provides a telecentric optical device capable of limiting the light passage region in a telecentric optical system without lowering the light utilization efficiency and the numerical aperture of the light receiving system. The purpose is to do.

[0009]

According to a first aspect of the invention, an object disposed on a predetermined inspection surface,
The first and second lenses are arranged so as to be separated from each other by a total distance of the focal length of the first lens and the focal length of the second lens, and the inspection plane position is set to the condensing position of the second lens. The telecentric optical means, the light source for hologram reference light, and the predetermined distance between the first lens and the second lens, which are spaced apart from the first lens by substantially the focal length of the first lens. , Diffracts the light from the light source for reference light and reproduces light equivalent to the light when one or more point light sources emitted from the condensing position of the first lens pass through this predetermined position. Which has been subjected to such an exposure process, and a light receiving device which is disposed in the vicinity of the converging position of the first lens and detects the light of the hologram reproduction light reflected by the object that has passed through the telecentric optical means. And a section The program, the hologram reproducing light is so subjected to the exposure, as reproduced from some areas of the hologram.

According to the second aspect of the invention, the object disposed on the predetermined inspection surface, the first and second lenses, and the focal length of the first lens and the focal length of the second lens are A distance from the first lens to the first lens, the telecentric optical means having the inspection surface position as the condensing position of the second lens, the light source for the hologram reference light, and the first lens to the first lens. Is disposed at a predetermined position between the first and second lenses, which is separated by approximately the focal length of, and diffracts the light from the light source for reference light and emits it from the condensing position of the first lens. A hologram subjected to an exposure process for reproducing light equivalent to the light when one or more point light sources pass through the predetermined position, and the hologram is disposed in the vicinity of the converging position of the first lens. Of the hologram reproduction light reflected by the object. The hologram reference light is arranged between the hologram and the reference light source for detecting light that has passed through the recentric optical means, and limits the hologram reference light so that the hologram reference light is applied to a partial area of the hologram. And a reference light area limiting unit for controlling the reference light area.

In the invention corresponding to claim 3, the object disposed on a predetermined inspection surface, the first and second lenses, and the focal length of the first lens and the focal length of the second lens are A distance from the first lens to the first lens, the telecentric optical means having the inspection surface position as the condensing position of the second lens, the light source for the hologram reference light, and the first lens to the first lens. Is disposed at a predetermined position between the first and second lenses, which is separated by approximately the focal length of, and diffracts the light from the light source for reference light and emits it from the condensing position of the first lens. A hologram subjected to an exposure process for reproducing light equivalent to the light when one or more point light sources pass through the predetermined position, and the hologram is disposed in the vicinity of the converging position of the first lens. Of the hologram reproduction light reflected by the object. The hologram is provided with a light receiving section for detecting light that has passed through the recentric optical means, and the hologram is such that the installation area of the hologram photosensitive material is limited so that the hologram reproduction light is reproduced from a partial area of the hologram. To do.

According to a fourth aspect of the present invention, the object disposed on a predetermined inspection surface, the first and second lenses, and the focal length of the first lens and the focal length of the second lens are A distance from the first lens to the first lens, the telecentric optical means having the inspection surface position as the condensing position of the second lens, the light source for the hologram reference light, and the first lens to the first lens. The first of which is separated by approximately the focal length of
And a predetermined position between the second lens and the inspection surface, diffracts the light from the reference light source, and emits the light from the condensing position of the first lens. A hologram that has been subjected to an exposure process so as to reproduce light equivalent to the light when one or a plurality of point light sources pass through this predetermined position, and is disposed in the vicinity of the converging position of the first lens. And a light receiving unit for detecting the light of the hologram reproduction light reflected by the object that has passed through the telecentric optical means, and the hologram is such that the hologram reproduction light is reproduced from a partial region of the hologram. Allow it to be exposed.

In the invention corresponding to claim 6, a pinhole having one or a plurality of openings, an object arranged on a predetermined inspection surface, the first and second lenses, and the first lens And the focal length of the second lens are spaced apart from each other, the pinhole opening position is the converging position of the first lens, and the inspection surface position is the second position.
Between the first and second lenses which are separated from the first lens by the focal length of the first lens, and the telecentric optical means which is the condensing position of the lens of It is arranged at a predetermined position, diffracts the light from the light source for reference light, and reproduces light equivalent to the light when one or more point light sources emitted from the pinhole pass through the predetermined position. And a hologram subjected to an exposure process as described above and the telecentric optical means are disposed on the opposite side of the pinhole, and the hologram reproduction light reflected by the object passes through the opening of the pinhole. The hologram is provided with a light receiving section for receiving the light, and the hologram is exposed as object light only to the central transmitted light that passes through the center of the pinhole of the point light source light emitted from the pinhole. The only reference light near the optical axis of the telecentric optical system, characterized in that the exposure is applied to be irradiated as.

In the invention corresponding to claim 7, a pinhole having one or a plurality of apertures, an object arranged on a predetermined inspection surface, the first and second lenses, and the first lens And the focal length of the second lens are spaced apart from each other, the pinhole opening position is the converging position of the first lens, and the inspection surface position is the second position.
Position between the telecentric optical means as the condensing position of the lens, the light source for the hologram reference light, and the first and second lenses separated from the first lens by the approximate focal length of the first lens. And, disposed at a predetermined position between the inspection surface, diffracts the light from the reference light source,
A hologram that has been subjected to an exposure process so as to reproduce light equivalent to the light when one or more point light sources emitted from the condensing position of the first lens pass through this predetermined position; The hologram reproducing light reflected by the object is disposed on the opposite side of the hole with a hole between the telecentric optical means, and a light receiving portion for receiving the light passing through the aperture of the pinhole, and The hologram is composed of the one or a plurality of point light sources that pass through a spatial filter disposed at a predetermined position which is separated from the first lens by the focal length of the first lens on the inspection surface side during hologram exposure. Is incident on the hologram so that only the centrally transmitted light of the point source light emitted from the pinhole that is transmitted through the center of the pinhole is exposed as object light. And said that you are.

[0015]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

[First Embodiment] FIG. 1 shows a first embodiment of the present invention.

In the first embodiment, the hologram 3 is used as a spatial filter arranged at the pupil position of the telecentric optical system (the optical Fourier transform plane position of the object light), and FIG. FIG. 1B shows the configuration of the optical system during hologram reproduction, and FIG. 1B shows the configuration of the optical system during hologram exposure. In FIG. 1, the point light source and the image forming point are shown as one for the sake of simplification, but the point light source and the image forming point are arranged one-dimensionally, and further, two-dimensionally. It may be arranged in a regular manner.

In FIG. 1 (a), 1 is a pinhole and 2 is a pinhole.
a and 2b are telecentric lenses, 3 is a glass substrate 5
A hologram having a hologram photosensitive material 4 coated thereon, 6 is an object, 7 is a light source for reference light having a light source 8, a lens 9 and a lens 10, 11 is a light-shielding mask for limiting the passage region of reference light, and 12 is a pinhole. 1 is a light receiving unit that receives light that has passed through 1.

In the structure shown in FIG. 1 (a), the hologram 3 is used as a means for generating point light source light, and it is as if the reference light from the reference light source 7 is incident and diffracted. The light that is emitted from the pinhole 1 is emitted for reproduction.

That is, when the reference light is incident on the hologram 3 from the light source 8 through the lenses 9 and 10, the hologram 3 reproduces light equivalent to the point light source existing in the opening of the pinhole 1. . Then, the reproduced light is imaged on the object 6 by the lens 2b. Further, the light reflected by the object 6 is incident on the lens 2a via the lens 2b and the hologram 3, and is condensed at the pinhole position of the pinhole 1 by the lens 2a. The light receiving unit 12 is arranged behind the pinhole position and receives the light passing through the pinhole. For example, if a photodetector is used as the light receiving unit 12, the position of the object 6 in the optical axis direction is measured as in the three-dimensional shape measuring apparatus using the confocal optical system shown in FIG. can do.

Here, the hologram 3 is arranged substantially at the pupil position of the telecentric lenses 2a and 2b, and the hologram 3 is exposed so as to function as a light-shielding mask for limiting the light area of the projected light. It has been subjected. Also,
The hologram 3 has a diffraction efficiency of, for example, 50%,
The object 6 is irradiated with 50% of the reference light, and about 50% of the reflected light from the object 6 passes through the hologram 3 and enters the light receiving unit 12. That is, in this embodiment, when the focal length of the lens 2a is f2 and the focal length of the lens 2b is f1, the position between the lenses 2a and 2b where the focal positions of these two lenses 2a and 2b are matched, that is, the pupil position. In addition, the exposed hologram 3 is provided so that only the light projecting system functions as a light-shielding mask.

Therefore, according to this hologram 3,
Although the projected light is generated from a part of the area of the hologram surface, the received light can be passed through the entire surface of the hologram, and the light utilization efficiency of the light receiving system is higher when the conventional hardware shading mask is used. Greatly improved compared to

FIG. 1 (b) shows a structure for exposing the hologram 3, in which the same pinhole 1, lens 2a, and reference light source 7 as those shown in FIG. 1 are used. Place in the same positional relationship. Here, in order to limit the area of the reference light incident on the hologram 3 to the hatched portion in FIG. 1A, the reference light source 7 and the hologram 3 are used.
A light-shielding mask 11 having a required opening is provided between and.

In this state, the reference light is made incident on the hologram 3 and the parallel light is made incident on the pinhole 1 as object light. Of course, at this time, the reference light and the object light are generated by splitting the light of one laser light source,
Interference occurs on the surface of the hologram 3. Further, at this time, the optical path length and the polarization direction of the reference light and the object light are matched.

As a result, the point light source image formed on the pinhole is incident on the hologram 3 in the state of being parallel light by the lens 2a and recorded. In this case, since the reference light and the object light are incident from one side of the hologram 3, the hologram 3 becomes a transmissive type.

When the exposure of the hologram 3 is completed as described above, the light receiving portion 12 is installed behind the pinhole 1. If the lens 2b is not installed during the previous hologram exposure, the lens 2b is installed to complete the telecentric optical system.

As described above, in this embodiment, the hologram 3 is exposed so as to limit the light area of the light projecting system.
Is placed at approximately the pupil position of the telecentric optical system, and the hologram acts as a light-shielding mask.Therefore, the light loss of the light receiving system is extremely reduced, and the decrease in the numerical aperture during light reception is minimized. It becomes possible to suppress.

Further, in this embodiment, since the hologram is made to have the functions of the light-shielding mask and the spatial filter, it is not necessary to actually dispose the light-shielding mask and the spatial filter, and the device structure can be made compact and Problems such as interference between the reference light optical system and the spatial filter can be avoided. In fact, the telecentric lens 2
The lenses a and 2b have a group lens structure for correcting aberrations, and a very narrow space is provided between the lenses.

In the case of FIG. 1A, the light shielding mask 11 is arranged at the time of reproducing the hologram, but the light shielding mask 11 can be omitted. That is, in the first embodiment, the light-shielding mask 11 is an indispensable constituent element only when the hologram 3 is exposed.

[Second Embodiment] FIG. 2 shows a second embodiment of the present invention.

In the second embodiment, as shown in FIG. 2 (b), by irradiating the whole surface of the hologram 3 with the reference light at the time of hologram exposure, all the object light emitted from the pinhole 1 is exposed. The hologram 3 is exposed. on the other hand,
At the time of reproducing the hologram, as shown in FIG. 2A, a light-shielding mask 11 is provided between the light source 7 for reference light and the hologram 3, and the region of the hologram 3 irradiated with the reference light by the light-shielding mask 11 is arranged. I try to limit it. Of course, also in this embodiment, the hologram 3 is arranged at the pupil position of the telecentric optical system.

As the light-shielding mask 11, for example, a variable iris diaphragm (camera diaphragm), a transmissive liquid crystal panel, or the like whose opening diameter or opening shape can be freely changed is used. The pattern for selecting the object light can be switched accordingly. In particular, by using a transmissive liquid crystal panel capable of giving an arbitrary two-dimensional pattern by an electric signal, it becomes possible to easily set an arbitrary light passage region.

[Third Embodiment] FIG. 3 shows a third embodiment of the present invention.

In the third embodiment, as shown in FIGS. 3 (a) and 3 (b), the hologram photosensitive material 4 is not provided on the entire surface of the glass substrate 5, but is provided on a partial region of the glass substrate 5. Then, the light projection area is limited.

That is, at the time of hologram exposure, FIG.
As shown in (b), the entire surface of the glass substrate 5 is irradiated with the reference light, but since the hologram photosensitive material 4 is applied only to a partial area of the glass substrate 5, it is emitted from the pinhole 1. Only part of the object light is exposed to the hologram 3.

At the time of reproducing the hologram, as shown in FIG. 3A, the reference light is incident on the entire surface of the hologram, or an appropriate light shielding mask 11 as shown in FIG. 2A is used as a reference light source. 7 and the hologram 3 so that the reference light is incident only on the region where the hologram photosensitive material 4 is applied. In any case, when the reference light is incident on the hologram 3, the light projected onto the lens 2b from the partial area of the hologram 3 in which the photosensitive material 4 is arranged is reproduced.

In this embodiment, when the hologram is reproduced, the projection efficiency is improved when the reference light is incident only on the area where the photosensitive material 4 is applied. Also in this embodiment, the hologram 3 is arranged at the pupil position of the telecentric optical system.

FIG. 4 shows a modification of the third embodiment. In this embodiment, the application area of the hologram photosensitive material 4 is removed after the hologram exposure to remove the embodiment shown in FIG. Similarly to the above, only the hologram photosensitive material region corresponding to the region where the desired object light is recorded is left. That is, in this case, similarly to FIG. 2B, after the object light is recorded on the entire surface of the hologram 3 on which the photosensitive material 4 is applied, the photosensitive member on which the desired object light is recorded. Only the area is left and the others are removed.

[Fourth Embodiment] FIG. 5 shows a fourth embodiment of the present invention.

In the fourth embodiment, at the time of exposure, as shown in FIG. 5 (b), the telecentric lenses 2a, 2
A spatial filter 13 such as a light-shielding mask is arranged at the pupil position of b (one lens 2b need not be arranged), and the hologram 3 is arranged between this pupil position and the image plane 14. There is. Further, since the spatial light filter 13 interferes with the reference light source 7, the reference light source 7 is made to enter the hologram 3 from the side opposite to the object light. That is, in this case, the hologram 3 is a reflection type.

At the time of reproducing the hologram, as shown in FIG. 5A, the spatial filter 13 at the pupil position is removed, and the entire surface of the hologram 3 (or only the exposed portion) is referenced by the reference light source 7. Irradiate with light. As a result, at the time of exposure, the projection light is reproduced only from a partial area (the area shown by hatching in FIG. 5A) of the hologram where the object light is limited and irradiated by the spatial filter 13 and is combined by the lens 2b. An image is formed at the image point.

As described above, according to the fourth embodiment, at the time of hologram exposure, the hologram exposure area is limited by the spatial filter 13 such as the light-shielding mask arranged at the pupil position, so that the projected light is limited. There is.

[Fifth Embodiment] FIG. 6 shows a fifth embodiment of the present invention.

In the fifth embodiment, during hologram exposure, the hologram 3 is arranged between the pupil positions of the telecentric lenses 2a and 2b and the pinhole 1 as shown in FIG. 6 (b). Then, in this state, the reference light is applied to the entire surface of the hologram 3. Further, at the time of reproducing the hologram, as shown in FIG. 6 (a), substantially the entire surface of the hologram is irradiated with the reference light to reproduce the projected light, and at the same time, the spatial filter 15 such as a light-shielding mask arranged at the pupil position.
Therefore, the passing area of the projected light is limited.

[Sixth Embodiment] FIG. 7 shows a sixth embodiment of the present invention. In the sixth embodiment, the present invention is applied to the optical pickup device.

That is, in FIG. 7, when the reference light is incident on the hologram 3 from the light source 7 for the reference light, the lens 2b reproduces light such that the light is imaged at a predetermined position on the surface of the optical disc 20. Such exposure is performed in advance. In this case, the hologram 3 is arranged, for example, at the pupil position between the telecentric lenses 2a and 2b.

Therefore, when the reference light is incident on the hologram 3, the reference light is diffracted and imaged at a predetermined position on the optical disc 20. Then, the reflected light is reflected by the lens 2
It is incident on the error / signal detection system 21 through b, the hologram 3 and the lens 2a. Then, by processing the optical signal incident on the error / signal detection system 21, the focusing of the optical pickup and the data on the optical disk 20 are decoded.

In such an optical pickup device, a light-shielding mask 11 for limiting the reference light incident on the hologram 3 is provided between the hologram 3 and the reference light source 7 so that the light is incident on the optical disc 20. It limits the emitted light.

In this embodiment, the technique corresponding to the second embodiment shown in FIG. 2 is applied to the optical pickup device, but other techniques shown in FIGS. 1, 3 and 4 are used. The techniques shown in FIGS. 5 and 6 may be applied to the optical pickup device.

[Seventh Embodiment] By the way, when the pinhole is irradiated with light (parallel light), the light emitted from the pinhole is shown in FIG.
As shown in FIGS. 9A and 9A, two types of wavefronts are generated: centrally transmitted light that transmits through the center of the pinhole and peripheral diffracted light that is diffracted at the edge of the pinhole. The light intensity profile and the light intensity pattern of the central transmitted light and the peripheral diffracted light are shown in FIG. 8 (b), FIG. 9 (b), and FIG.
9C and 9C, the light intensities thereof are not uniform. Further, FIGS. 10 (a), (b), and (c) show the combined light of the central transmitted light and the peripheral diffracted light, their light intensity profile, and the light intensity pattern, respectively. A dark part region is formed at the boundary between and by the interference of these two lights.

Therefore, in the case of the above-mentioned embodiments in which the light that has passed through the pinhole 1 is incident on the hologram, two different light beams will be used if no consideration is given during hologram exposure. A wavefront having an intensity profile and a light intensity pattern is recorded on the hologram, which causes deterioration of the quality of the projected image and eventually deterioration of measurement accuracy. In particular, the diffracted light generated at the edge of the pinhole reduces the SN ratio, which in turn reduces the measurement accuracy. Then, the influence of the peripheral diffracted light becomes more remarkable when the light source has high coherence such as laser light.

Therefore, in the seventh embodiment, the hologram 3 is exposed so that only the centrally transmitted light of the light emitted from the pinhole is used as the reproduction light. That is, the peripheral diffracted light is removed.

FIG. 11 shows a seventh embodiment of the present invention, and this FIG. 11 shows the structure when the hologram 3 is exposed.

In this hologram exposure apparatus, a pinhole array 30 in which a plurality of pinholes are two-dimensionally arranged is arranged on the object plane, and parallel light is incident on this pinhole array 20.

The lenses 2a and 2b form a telecentric system as in the previous embodiment, and the pinhole array 3
Each light emitted from each 0 pinhole is collected at the pupil position by the lens 2a. The hologram 3 is arranged at the pupil position, and the reference light is incident on the hologram 3 from the reference light source 7.

Here, an elliptical aperture mask 11 is provided between the reference light source 7 and the hologram 3, and the central transmitted light in the exposure region of the hologram 3 is provided by the elliptical aperture mask 11. The reference light is made incident only on the central region irradiated with. That is, the reference light is prevented from entering the hologram area irradiated with the peripheral transmitted light.

Therefore, in this case, the hologram 3 is exposed only to the central transmitted light of the light from the pinhole array 30. The reason why the opening mask 11 is an ellipse is that the reference light with which the hologram is irradiated at an angle is a perfect circle on the photosensitive material surface 4 of the hologram 3. Further, in FIG. 11, the other lens 2b and the object 6 to be inspected are arranged, but of course these are not necessary for hologram exposure.

When the exposure of the hologram 3 is completed as described above, a light receiving section array (not shown) is installed on the rear side (upper side in the drawing) of the pinhole array 30. And
If the lens 2b is not installed during the previous hologram exposure, the lens 2b is installed to complete the telecentric optical system.

[Eighth Embodiment] FIG. 12 shows an eighth embodiment of the present invention. FIG. 12 shows the configuration when the hologram 3 is exposed.

In this hologram exposure apparatus as well, a pinhole array 30 in which a plurality of pinholes are two-dimensionally arranged is arranged on the object plane, and parallel light is incident on this pinhole array 20.

The lenses 2a and 2b constitute a telecentric system as in the previous embodiment, and the pinhole array 3
Each light emitted from each 0 pinhole is collected at the pupil position by the lens 2a. At the pupil position, a circular aperture mask 40 having a circular aperture that transmits only the central transmission of the light incident from the lens 2a is disposed, and this circular aperture mask 40 excludes peripheral diffracted light.

The hologram 3 is arranged between the pupil position and the lens 2b, and the reference light is incident on the hologram 3 from the reference light source 7.

Therefore, in this case, only the central transmitted light of the light from the pinhole array 30 is incident on the hologram 3 as the object light, and this is exposed by being interfered with the reference light. Although the other lens 2b and the object 6 to be inspected are arranged also in FIG. 12, these are not necessary for hologram exposure.

When the exposure of the hologram 3 is completed as described above, a light receiving section array (not shown) is installed on the rear side (upper side in the drawing) of the pinhole array 30. Further, the circular opening mask 40 is removed. If the lens 2b is not installed during the previous hologram exposure, the lens 2b is installed to complete the telecentric optical system.

When producing a hologram that reproduces only the light transmitted through the center of the pinhole, the technique of limiting the area of the hologram photosensitive material itself is used as in the embodiment shown in FIG. 3 or 4. You may do it.

Further, in each of the above-described embodiments, for the light-shielding mask and the spatial filter for limiting the reference light or the object light, it is better to form the light-shielding mask on the optical substrate by an etching process or the like to reduce the thickness of the mask itself. It is suitable.

The light-shielding mask and the spatial filter used for exposing the hologram and reproducing the hologram are not limited to those for transmitting only the central portion of the light, but are annular, lattice,
It suffices to select an arbitrary pattern such as a dot sequence that allows desired light projection. Similarly, when limiting the area of the hologram photosensitive material itself, the limiting pattern is arbitrary.

The light-shielding mask arranged at the pupil position functions as a spatial filter on the optical Fourier transform plane (pupil position) of the image of the pinhole array. Therefore, various effects such as (1) improving the resolution (2) removing noise light (3) being able to project pattern light in an arbitrary shape can be obtained by selecting various patterns of this light-shielding mask. To be

In each embodiment, the hologram is
Any type such as a transmissive type, a reflective type, an edge illuminated type, and an evanescent wave type may be used.

Further, each of the above embodiments may be applied to the three-dimensional shape measuring apparatus shown in FIG. When the above-described embodiments are applied to the three-dimensional shape measuring apparatus, the object to be inspected may be moved and scanned in the height direction of the object to be inspected by the moving stage, or the entire confocal optical device may be used. It may be configured to be movable in the height direction, and further, the telecentric lens 2a,
2b may be configured to be movable in the height direction. Further, in the telecentric optical system, the magnification may be any one of magnification, enlargement and reduction.

Further, the plurality of pinhole (point light source) images shown in the embodiment are not limited to regular arrangements, but are general pattern images which are interpreted as including a plurality of point light sources. I don't care. That is, it may be an image of a line or a plane.

Each constituent element in the above-mentioned embodiment is an example, and other constitutions may be adopted as long as they can achieve the same functions as those shown in the above-mentioned embodiment. Good.

[0073]

As described above, according to the present invention,
Since the hologram that has been exposed to limit the light area of the light projecting system is arranged at the approximate pupil position of the telecentric optical system, and the hologram acts as a light shielding mask, the light loss of the light receiving system is caused. And the decrease in the numerical aperture at the time of receiving light can be minimized. Further, since the hologram is made to have the functions of the light-shielding mask and the spatial filter, it is not necessary to actually dispose the light-shielding mask and the spatial filter, and the device configuration can be made compact, and the reference light optical system and the spatial filter can be used. It is possible to avoid problems such as interference with.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a second embodiment of the present invention.

FIG. 3 is a diagram showing a third embodiment of the present invention.

FIG. 4 is a diagram for explaining a modification of the third embodiment.

FIG. 5 is a diagram showing a fourth embodiment of the present invention.

FIG. 6 is a diagram showing a fifth embodiment of the present invention.

FIG. 7 is a diagram showing a sixth embodiment of the present invention.

FIG. 8 is a diagram illustrating center transmitted light due to a pinhole.

FIG. 9 is a diagram illustrating peripheral diffracted light due to a pinhole.

FIG. 10 is a diagram illustrating light emitted from a pinhole.

FIG. 11 is a diagram showing a seventh embodiment of the present invention.

FIG. 12 is a diagram showing an eighth embodiment of the present invention.

FIG. 13 is a diagram showing a conventional technique.

FIG. 14 is a diagram for explaining a pupil position.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Pinhole array 2a, 2b ... Telecentric lens 3 ... Hologram 4 ... Hologram photosensitive material 5 ... Glass substrate 6 ... Object 7 ... Reference light source 11 ... Shading mask 12 ... Light receiving part 20 ... Optical disk 30 ... Pinhole array 40 ... Circular opening mask

Claims (7)

[Claims] 1. An object arranged on a predetermined inspection surface and a first lens and a second lens are separated from each other by a total distance of a focal length of the first lens and a focal length of the second lens. At the same time, the telecentric optical means is disposed and the inspection surface position is the condensing position of the second lens, the hologram reference light source, and the first lens is separated from the first lens by the approximate focal length of the first lens. , One or a plurality of points disposed at a predetermined position between the first and second lenses, diffracting the light from the reference light source, and emitting the light from the condensing position of the first lens. A hologram that has been subjected to an exposure process that reproduces light equivalent to the light when the light source light passes through this predetermined position; and a hologram that is disposed near the converging position of the first lens and is reflected by the object. The telecentric optical means for reproducing the hologram reproduction light. A telecentric optical device comprising: a light receiving unit that detects light that has passed therethrough; and that the hologram is exposed so that the hologram reproduction light is reproduced from a partial region of the hologram. 2. An object disposed on a predetermined inspection surface and the first and second lenses are separated by a total distance of a focal length of the first lens and a focal length of the second lens. At the same time, the telecentric optical means is disposed and the inspection surface position is the condensing position of the second lens, the hologram reference light source, and the first lens is separated from the first lens by the approximate focal length of the first lens. , One or a plurality of points disposed at a predetermined position between the first and second lenses, diffracting the light from the reference light source, and emitting the light from the condensing position of the first lens. A hologram that has been subjected to an exposure process that reproduces light equivalent to the light when the light source light passes through this predetermined position; and a hologram that is disposed near the converging position of the first lens and is reflected by the object. The telecentric optical means for reproducing the hologram reproduction light. A reference light region limiting unit that is provided between the light receiving unit that detects the light passing therethrough and the hologram and the reference light source, and that limits the hologram reference light so that the hologram reference light is irradiated to a partial region of the hologram. And a telecentric optical device. 3. An object disposed on a predetermined inspection surface and the first and second lenses are separated by a total distance of a focal length of the first lens and a focal length of the second lens. At the same time, the telecentric optical means is disposed and the inspection surface position is the condensing position of the second lens, the hologram reference light source, and the first lens is separated from the first lens by the approximate focal length of the first lens. , One or a plurality of points disposed at a predetermined position between the first and second lenses, diffracting the light from the reference light source, and emitting the light from the condensing position of the first lens. A hologram that has been subjected to an exposure process that reproduces light equivalent to the light when the light source light passes through this predetermined position; and a hologram that is disposed near the converging position of the first lens and is reflected by the object. The telecentric optical means for reproducing the hologram reproduction light. And a light receiving section for detecting light passing therethrough, wherein the hologram is characterized in that a hologram photosensitive material installation area is limited so that the hologram reproduction light is reproduced from a partial area of the hologram. Optical device. 4. An object arranged on a predetermined inspection surface and the first and second lenses are separated by a total distance of a focal length of the first lens and a focal length of the second lens. At the same time, the telecentric optical means is disposed and the inspection surface position is the condensing position of the second lens, the hologram reference light source, and the first lens is separated from the first lens by the approximate focal length of the first lens. It is arranged at a predetermined position between the first lens and the second lens and the inspection surface, diffracts the light from the light source for reference light, and converges the light on the first lens. A hologram that has been subjected to an exposure process so as to reproduce light equivalent to the light when one or a plurality of point light sources emitted from the light passes through the predetermined position; and a hologram near the light collecting position of the first lens. The hologram reproduction light that is arranged and reflected by the object is And a light receiving unit for detecting light that has passed through the recentric optical unit, wherein the hologram is exposed so that the hologram reproduction light is reproduced from a partial region of the hologram. Telecentric optical device. 5. The hologram according to claim 1, wherein at the time of hologram exposure, the hologram is passed through a spatial filter arranged at a predetermined position separated from the first lens on the inspection surface side by a focal length of the first lens. 5. The telecentric optical device according to claim 4, wherein the exposure is performed such that the hologram reproduction light is reproduced from a partial area of the hologram when a plurality of point light sources are incident on the hologram. 6. A pinhole having one or a plurality of apertures, an object arranged on a predetermined inspection surface, first and second lenses, a focal length of the first lens and a second lens. The pinholes are arranged so as to be separated from each other by the total distance of the focal lengths of the lenses, the pinhole opening position is set as the condensing position of the first lens, and the inspection surface position is set as the condensing position of the second lens. A telecentric optical means, a hologram reference light source, and a predetermined position between the first lens and the second lens, which is separated from the first lens by a substantially focal length of the first lens, An exposure process is performed to diffract the light from the light source for reference light and reproduce light equivalent to the light when one or more point light sources emitted from the pinhole pass through the predetermined position. A hologram and the telescope across the pinhole. The hologram reproduction light reflected by the object and receiving light that has passed through the aperture of the pinhole, and the hologram is Of the point source light emitted from the pinhole, the reference light is irradiated only near the optical axis of the telecentric optical system so that only the central transmitted light transmitted through the center of the pinhole is exposed as the object light. Telecentric optical device characterized in that 7. A pinhole having one or a plurality of apertures, an object arranged on a predetermined inspection surface, first and second lenses, a focal length of the first lens and a second lens. The pinholes are arranged so as to be separated from each other by the total distance of the focal lengths of the lenses, the pinhole opening position is set as the condensing position of the first lens, and the inspection surface position is set as the condensing position of the second lens. Between the telecentric optical means, the hologram reference light source, the position between the first and second lenses separated from the first lens by the approximate focal length of the first lens, and the inspection surface. At a predetermined position, diffracts the light from the light source for reference light, and emits one or a plurality of point light sources emitted from the condensing position of the first lens when passing through the predetermined position. A hologram that has been exposed to light that is equivalent to light. And a light receiving section which is arranged on the opposite side of the telecentric optical means with the pinhole interposed therebetween, and which receives the hologram reproduction light reflected by the object and which has passed through the opening of the pinhole. In addition, the hologram is configured such that, during hologram exposure, the hologram is provided with the above-mentioned 1 to 1 through a spatial filter arranged at a predetermined position separated from the first lens on the inspection surface side by a focal length of the first lens. When a plurality of point source light beams are incident on the hologram, exposure is performed so that only the central transmitted light beam that passes through the center of the pinhole among the point source light beams emitted from the pinhole is exposed as object light. Telecentric optical device characterized in that