JP2000047553A - Method and device for producing hologram - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately produce a hologram having a desired interference stripe pattern even when the phase and/or amplitude modulation due to a spatial optical modulator is not sufficient. SOLUTION: The distribution of phases and/or amplitude on the hologram surface related to a desired regenerative wave front is calculated by a computer, the distribution of phases and/or amplitude calculated by the computer is applied to a laser beam and made into object light 1A' by a spatial optical modulator 2, the distribution of phases and/or amplitude of the object light 1A' due to the spatial optical modulator 2 is formed into an image and made incident on a photosensitive material 5 for hologram recording by image forming systems 31 and 32 while transmitting only a desired light component arranged near the Fourier plane of the modulated object light 1A' inside the image forming system through a light shielding means 4, reference light 1B coherent with the object light 1A' is made incident on the photosensitive material 5 and interference fringes are recorded by the interference of both lights.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing a hologram for reproducing an arbitrary wavefront, and more particularly to a method and an apparatus for spatially modulating a light beam, even if the phase and / or amplitude modulation by the spatial light modulator is insufficient. The present invention relates to a method and an apparatus for producing a hologram capable of producing a hologram having an interference fringe pattern with high accuracy.

[0002]

2. Description of the Related Art Generally, a hologram is an excellent medium for reproducing an arbitrary wavefront. However, a hologram obtained by photographing using ordinary laser light interference actually requires a subject or the like, and thus the subject or the obtained hologram has its own limitation / limitation.

On the other hand, a computer generated hologram (CGH: Comput
er Generated Hologram) is a technique capable of producing a hologram that cannot be produced by interference with a laser beam or the like. That is, if a computer calculates a complex amplitude distribution on a hologram surface for reproducing a desired wavefront, and produces a device that physically realizes this, a CGH is completed.

By the way, as a method for manufacturing such a CGH, conventionally, a calculated pattern is expressed by X
-A method of drawing by a Y plotter or the like and reducing the size of a photograph to an appropriate size, or a method of directly drawing a pattern using a device having high resolution.

[0005] However, in these methods, the amount of calculation by the computer is enormous, and therefore, a long processing time is required, and the amount of data to be handled is enormous. Also, when producing, a huge amount of data must be drawn or the like, which also requires a long process, and it is particularly impossible to produce a CGH having a relatively large size.

Therefore, recently, as a method for solving such a problem, for example, Japanese Patent Application No. Hei 6-10569.
No. 4 "has been proposed.

That is, the method for producing this hologram is as follows.
The spatial light modulator generates a phase or a distribution of the phase and amplitude of the object light (hereinafter, referred to as phase and / or amplitude), reduces the image of the object light, and simultaneously records interference fringes by causing interference with the reference light. How to

[0008]

However, in such a method, generally, when phase and / or amplitude modulation is performed using a liquid crystal display device or the like as a spatial light modulator, an object is controlled by the spatial light modulator. It is very difficult to accurately modulate the phase and / or amplitude distribution of light, and it is difficult to accurately produce a hologram having a desired interference fringe pattern.

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the amount of calculation on a computer, to easily produce a hologram for reproducing a high-precision arbitrary wavefront in a short time, and to further reduce the phase by a spatial light modulator. It is another object of the present invention to provide a method and an apparatus for producing a hologram that can accurately produce a hologram having a desired interference fringe pattern even when amplitude modulation is insufficient.

[0010]

According to a first aspect of the present invention, there is provided a method for producing a hologram for reproducing an arbitrary wavefront, comprising the steps of: The above phase and / or amplitude distribution is calculated, and the phase and / or amplitude distribution calculated by the computer is given to the laser light by the spatial light modulation element to produce object light, and the spatial light modulation is performed by the imaging system. The distribution of the phase and / or amplitude of the object light by the element is imaged while transmitting the light through a light-shielding unit that transmits only a desired light component disposed near the Fourier plane of the modulated object light in the image forming system. Incident on the photosensitive material for hologram recording, the object light and the coherent reference light are incident on the photosensitive material, and interference fringes are recorded by interference between the two.

Here, it is particularly preferable that the light-shielding means is arranged on the Fourier plane of the phase and / or amplitude distribution of the spatial light modulator in the imaging system, for example, as described in claim 2.

The light shielding means preferably transmits only the 0th-order diffracted light component determined by the cell structure of the spatial light modulator, for example. Furthermore, it is preferable that the light-shielding means transmits only a light component determined from a cell structure of the spatial light modulator and a result of distribution calculation by a computer, for example.

Therefore, in the hologram manufacturing method according to the first to fourth aspects of the present invention, the distribution of the phase and / or the amplitude on the hologram surface with respect to the desired reproduction wavefront is calculated by the computer, and the spatial light modulator uses When the phase and / or amplitude distribution is given to laser light to form object light, and when the phase and / or amplitude distribution of the object light is imaged by an image forming system and incident on a photosensitive material, the phase and / or amplitude distribution in the image forming system After passing through the light blocking means for transmitting only the desired light component arranged near the Fourier plane of the modulated object light, the reference light having coherence with the object light is incident on the photosensitive material to record interference fringes. By doing so, object light having a desired phase and / or amplitude distribution can be incident on the surface of the photosensitive material, so that phase and / or amplitude modulation by the spatial light modulator is insufficient. Even, a hologram having desired interference fringe pattern can be formed with high accuracy.

Further, since the carrier can be excluded in the calculation on the computer, the calculation amount is extremely small, the calculation can be performed in a short time, and the data amount can be reduced.

Further, in the exposure process using a laser beam, the amount of data to be handled is small, and a hologram of a certain size can be produced by one exposure, so that a highly accurate hologram can be easily produced in a short time. .

On the other hand, according to the invention of claim 5, the above-mentioned claim 1 is provided.
In the method of manufacturing a hologram according to any one of claims 4 to 6, a reduction imaging system is used as the imaging system.

Therefore, in the hologram manufacturing method according to the fifth aspect of the present invention, by using a reduced image forming system as an image forming system, even if a spatial light modulator having a coarse resolution is used, object light can be expressed with high resolution. A hologram having a sufficiently fine change in interference fringe pattern can be manufactured.

According to the sixth aspect of the present invention, in the first aspect,
In the method of manufacturing a hologram according to any one of claims 5 to 5, a spatial light modulation element capable of modulating an amplitude distribution of transmitted light is used as the light shielding means.

Therefore, in the hologram manufacturing method according to the sixth aspect of the present invention, the light shielding area can be arbitrarily changed by using a spatial light modulation element capable of modulating the amplitude (intensity) distribution of transmitted light as the light shielding means. Therefore, only the necessary component of the object light can be selectively transmitted. That is, the object light can be optimized in each of the holograms obtained by one exposure.

According to a seventh aspect of the present invention, in the method for producing a hologram according to any one of the first to sixth aspects, the reference light is made to enter through an imaging system.

Therefore, in the method of manufacturing a hologram according to the present invention, the selection of the lens system and the like of the apparatus can be performed, for example, by making the reference light incident through the imaging system, so that a lens having a short focal length can be used. The range is increased, and it is possible to cope with downsizing of the device.

According to the invention of claim 8, the above-mentioned claim 1 is provided.
In the method of manufacturing a hologram according to any one of claims 7 to 7, the photosensitive material is moved in the plane of the photosensitive material.

Therefore, in the method of manufacturing a hologram according to the eighth aspect of the present invention, since the photosensitive material is moved within the photosensitive material plane, the exposure can be performed while appropriately changing the exposure position on the photosensitive material. It becomes easy to produce a hologram of a large size.

Further, according to an eleventh aspect of the present invention, in the method for producing a hologram according to any one of the first to tenth aspects, as a result of the distribution calculation by the computer, the phase and / or the phase by the spatial light modulator is obtained. If the frequency component of the amplitude distribution has a large width, the phase and / or
Alternatively, the distribution of the amplitude is distributed for each of a plurality of small frequency bands to create a distribution, and interference fringes are recorded for each frequency band,
All the frequency bands are subjected to multiple exposure.

Therefore, in the hologram manufacturing method according to the eleventh aspect, the modulation pattern of the spatial light modulator is divided into modulation patterns of several frequency bands, and the modulation pattern of one frequency band is subjected to one exposure. By using, unnecessary object light components for each frequency pattern are shielded by light shielding means, and by sequentially exposing the divided frequency patterns,
As a result, a desired interference fringe pattern can be obtained on the photosensitive material.

According to a twelfth aspect of the present invention, there is provided an apparatus for producing a hologram for reproducing an arbitrary wavefront,
A spatial light modulator that gives a laser beam a phase and / or amplitude distribution on a hologram surface with respect to a desired reproduction wavefront calculated by a computer and serves as object light, and a front focal position is located at the position of the spatial light modulator. A first lens disposed so as to coincide with the first lens, and disposed at a position opposite to the spatial light modulator side away from the first lens by a distance corresponding to the sum of the focal length of the first lens and its own focal length An imaging system, which is composed of a divided second lens and forms an image of the phase and / or amplitude distribution of the object light by the spatial light modulator, a rear focal position of the first lens and a front focal point of the second lens A light-blocking means arranged to match the position and transmitting only the desired light component; an object light arranged to match the rear focal position of the second lens and transmitted through the light-shielding means; And coherent A certain reference light and a light-sensitive material for hologram recording to be incident respectively.

Therefore, in the hologram manufacturing apparatus according to the twelfth aspect, the same operation as the first to fourth aspects can be obtained. Claim 13
In the hologram manufacturing apparatus according to the twelfth aspect of the present invention, the reference light is incident through an imaging system. Therefore, in the hologram manufacturing apparatus according to the thirteenth aspect, the same effect as that of the seventh aspect can be obtained.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a method of manufacturing a hologram according to the above-described conventional hologram manufacturing method, wherein only a desired light component is transmitted in the vicinity of the Fourier plane of object light in an imaging system for a spatial light modulator. By disposing the variable aperture means, even if the modulation of the phase and / or the amplitude of the object light by the spatial light modulator is insufficient, it is possible to record a desired interference fringe.

Hereinafter, embodiments of the present invention based on the above concept will be described in detail with reference to the drawings. (First Embodiment) FIG. 1 is a schematic diagram showing a configuration example of a CGH manufacturing apparatus for realizing a hologram manufacturing method according to the present embodiment.

That is, as shown in FIG. 1, the CGH manufacturing apparatus according to the present embodiment converts the distribution of the phase and / or amplitude on the hologram plane with respect to a desired reproduction wavefront calculated by a computer (not shown) into a laser beam 1A. , And the first lens 31 and the focal length of the first lens 31 that are arranged so that the front focal position coincides with the arrangement position of the spatial light modulator 2. f1
And the first focal length f2, the distance corresponding to the sum of
And a second lens 32 disposed at a position on the opposite side of the spatial light modulation element 2 away from the lens 31 to image the distribution of the phase and / or amplitude of the object light 1A 'by the spatial light modulation element 2. The imaging system and the Fourier plane of the modulated object beam 1A 'in the imaging system are arranged so as to coincide with the rear focal position of the first lens 31 and the front focal position of the second lens 32. A light-blocking means 4 disposed near the light path for transmitting only a desired light component; an object light 1A 'disposed so as to coincide with a rear focal position of the second lens 32 and transmitted through the light-shielding means 4; The hologram recording photosensitive material 5 on which the light 1A 'and the coherent reference light (laser light) 1B are respectively incident.

Here, it is preferable that the light shielding means 4 is arranged on the Fourier plane of the phase and / or amplitude distribution of the spatial light modulator 2 in the imaging system. As the light shielding means 4, only the light component determined by the cell structure of the spatial light modulator 2 is transmitted, or only the light component determined by the cell structure of the spatial light modulator 2 and the result of the distribution calculation by the computer is transmitted. It is made to transmit.

Further, as the light shielding means 4, a spatial light modulator (eg, a spatial light modulator) capable of modulating the amplitude (intensity) distribution of transmitted light is used.
Liquid crystal display device). On the other hand, it is preferable to use a reduced imaging system as the imaging system. In other words, for reduction imaging, for example, a lens having a focal length f2 shorter than the focal length f1 of the first lens 31 is replaced with a second lens.
It is sufficient to use these two lenses 3.
The ratio of the focal length of 1 to 32 is the reduction ratio.

As the spatial light modulator 2, it is preferable to use a liquid crystal display device. Next, a method of manufacturing a hologram using the CGH manufacturing apparatus of the present embodiment configured as described above will be described.

In the present embodiment, a hologram is manufactured by the following method. That is, as shown in FIG. 1, first, the phase and / or phase on a hologram surface for forming a desired reconstructed wavefront are calculated by a computer (not shown).
Or calculate the amplitude distribution.

Next, the laser light emitted from a laser light source (not shown) is divided into two, and one of the laser lights 1B is incident on the hologram recording photosensitive material 5 as reference light.

Further, the other laser beam 1A is made incident on the spatial light modulator 2, and the spatial light modulator 2
The laser beam 1A is subjected to phase and / or amplitude modulation to obtain an object beam 1A '.

At this time, the spatial light modulator 3 modulates the phase and / or the amplitude to form a desired reproduced wavefront calculated by the computer, and this reproduced wavefront does not include any consideration regarding the carrier wave. Absent.

Thereafter, the object light 1A 'is formed by the imaging system.
In the phase and / or amplitude distribution, the magnification in the direction orthogonal to the incident direction of the object light 1A 'is reduced, and the light is incident on the photosensitive material 5 at the same position as the laser light 1B.

Here, when the phase and / or amplitude distribution of the object light 1A 'is imaged by the image forming system and incident on the photosensitive material 5, the Fourier plane of the modulated object light 1A' in the image forming system is obtained. After passing through the light-shielding means 4 that transmits only the desired light component disposed in the object, the object light 1A 'and the reference light 1B having coherence are incident on the photosensitive material 5 to record interference fringes. Since the object light 1A 'having a desired phase and / or amplitude distribution can be incident on the surface of the photosensitive material 5, even if the phase and / or amplitude modulation by the spatial light modulator 2 is insufficient, a desired interference fringe pattern can be obtained. The hologram is produced with high accuracy.

Thus, the reference light (laser light 1) having coherence with the object light (laser light) 1A '
B) is incident, and a desired hologram is produced by interference between the two, that is, a desired reproduction wavefront (laser light 1A ')
An interference fringe between the carrier and the carrier wave provided by the reference light (laser light 1B) is recorded as a hologram on the photosensitive material 5.

The hologram recorded in this way is subjected to processing such as development, if necessary,
By inputting appropriate illumination light, a desired reproduction wavefront can be obtained.

The reproduced wavefront in this embodiment is
Any wavefront can be applied, for example non-existent,
Alternatively, it is possible to easily display a three-dimensional object that cannot be obtained by a normal method even if it actually exists, and realize an optical element or the like.

Next, in the hologram manufacturing method according to the present embodiment as described above, the parallel light laser beam 1A is incident on the spatial light modulator 2, and the phase and / or amplitude is After modulating the distribution of
Reference light (laser light) which is imaged by the image forming system (lens system) and is incident on the photosensitive material 5 and is also incident obliquely at the same time.
By causing interference with 1B, an interference fringe is recorded to produce a hologram.

Here, the image forming system has a function of forming an image of the distribution of the phase and / or amplitude of the spatial light modulator 2 on the photosensitive material 5, and the phase of the spatial light modulator 2 in the image forming system. A light-shielding unit 4 that transmits only a desired light component is arranged near the Fourier plane of the amplitude distribution.

For this reason, since the carrier can be excluded in the calculation on the computer, the amount of calculation is extremely small.
The calculation can be performed in a short time, and the data amount (the data amount is twice or more the frequency of the interference fringes) can be reduced. Further, in an exposure process using a laser beam, the amount of data to be handled is small, and a hologram of a certain size can be manufactured by one exposure, so that a highly accurate hologram can be easily manufactured in a short time. Furthermore, when the imaging system has a reduced imaging function, even if the spatial light modulator 2 having a coarse resolution is used, the object light can be expressed at a higher resolution than the spatial light modulator 2 and sufficiently fine interference fringes can be obtained. A hologram having a pattern change can be manufactured.

That is, the carrier wave is necessary for separating the reproduction wavefront reproduced by the produced hologram from the illumination light incident for reproduction. In general, the carrier is higher in frequency than the phase / amplitude distribution that forms the reconstructed wavefront on the hologram plane, so the carrier requires a huge amount of data and high resolution in the hologram. In the present embodiment using the interference by the laser light, the carrier is replaced with a phase and / or amplitude distribution on the photosensitive material 5 depending on the incident angle of the reference light 1B.

Therefore, in this embodiment, since only the phase and / or amplitude distribution of the reproduced wavefront, which requires only a relatively coarse resolution, needs to be processed, the data amount is small, the calculation is short, and the comparatively coarse is used. A hologram having a sufficiently fine interference fringe pattern can be produced even by using the spatial light modulation element 2 having a high resolution.

Here, in general, it is difficult to accurately perform phase and / or amplitude modulation by the spatial light modulator 2, and it is difficult to obtain an insufficient amount of phase and / or amplitude modulation or to involve an error. There are many.

At this time, even if the phase and / or amplitude modulation by the spatial light modulator 2 is reproduced on the photosensitive material 5, a desired interference fringe cannot be obtained. Therefore, the light shielding means 4 is arranged at the rear focal position of the first lens 31 to block unnecessary light components due to the cell structure of the spatial light modulator 2 and scattering characteristics, etc. By blocking the diffracted light component generated due to inaccurate amplitude modulation, a hologram composed of desired interference fringes can be produced.

The distribution of the diffracted light component generated due to inaccurate phase and / or amplitude modulation and the light component corresponding to the desired phase and / or amplitude modulation at the rear focal position of the first lens 31 is as follows: Each of them differs depending on the phase and / or amplitude pattern modulated by the spatial light modulator 2.

That is, in order to more precisely extract the light component corresponding to the desired phase and / or amplitude modulation, the light-shielding pattern of the light-shielding means 4 arranged at the rear focal position of the first lens 31 is changed each time. There is a need.

Therefore, it is preferable to use a spatial light modulator capable of modulating the intensity (amplitude) distribution of transmitted light as the light shielding means 4. In the above case, the light distribution at the rear focal position of the first lens 31 has a relationship between the phase and / or amplitude distribution of the spatial light modulator 2 and Fourier transform.

Accordingly, the light distribution at the rear focal position of the first lens 31 can be easily calculated using a computer, and the distribution of the desired light component can be easily grasped. Can be properly prepared.

FIG. 2 shows the light distribution at the rear focal position of the first lens 31 (= Fourier plane with respect to the phase and / or amplitude distribution of the spatial light modulator 2) and the corresponding light shielding pattern of the light shielding means 4. It is a figure showing an example of. FIG. 2 shows a case where a plane wave inclined in the X direction is considered as a desirable light distribution.

FIG. 2A shows a case where the spatial light modulator 2 performs perfect phase modulation, and FIG. 2B shows a case where the spatial light modulator 2 performs ideal phase modulation. FIG. 2C shows a case where the phase modulation of the spatial light modulator 2 is insufficient (there is a cell structure).

Here, as shown in FIG. 2 (a), when the spatial light modulator 2 performs perfect ideal phase modulation, there is no need for light shielding because only desired light exists. However, in practice, since almost all the spatial light modulators 2 have a cell structure, even if the spatial light modulators 2 are ideally phase- and / or amplitude-modulated, the period shown in FIG. Diffraction light is generated.

In this case, since the period of the diffraction component due to the cell structure does not depend on the modulation pattern on the spatial light modulator 2, the opening size is smaller than the period of the diffraction component due to the cell structure. A simple light-shielding pattern may be used.

That is, a light-shielding pattern that allows only light components determined by the cell structure of the spatial light modulator 2 to pass through may be used. On the other hand, the phase of the spatial light modulator 2 and / or
Or when the amplitude modulation is insufficient or accompanied by an error (this applies to many existing spatial light modulators)
, Many diffracted lights appear as shown in FIG.

However, on the Fourier surface, in many cases, various diffracted light components are separated as shown in the figure. Therefore, if the light-shielding pattern of the light-shielding means 4 is set so that only the desired light component is passed, the desired light can be obtained. Is obtained, and a desired interference fringe can be recorded on the photosensitive material 5.

That is, the cell structure of the spatial light modulator 2
The light-shielding pattern of the light-shielding means 4 may be set so that only the light component determined from the result of the distribution calculation by the computer is transmitted.

FIG. 3 is a diagram showing an example of the phase distribution on the spatial light modulator 2 (in the case of producing a plane wave inclined in the X direction). 3A is a desirable phase distribution, FIG. 3B is a phase distribution when the spatial light modulator 2 has a cell structure, and FIG.
(C) shows a case where the phase modulation of the spatial light modulator 2 is incorrect (no cell structure).

As described above, in the present embodiment, the distribution of the phase and / or the amplitude calculated by the computer by the spatial light modulator 2 is given to the laser light 1A to obtain the object light 1A '. When the phase and / or amplitude distribution is imaged by the imaging system and incident on the photosensitive material 5, only the desired light component arranged on the Fourier plane of the modulated object light 1A 'in the imaging system is removed. Light blocking means 4 for transmission
Is transmitted, the object light 1A 'and the coherent reference light 1B are made incident on the photosensitive material 5 to record the interference fringes. Therefore, the object light having a desired phase and / or amplitude distribution is recorded. Can be incident on the surface of the photosensitive material 5, so that even if the phase and / or amplitude modulation by the spatial light modulator 2 is insufficient, a hologram having a desired interference fringe pattern can be produced with high accuracy.

Further, since the carrier can be excluded in the calculation on the computer, the calculation amount is extremely small, the calculation can be performed in a short time, and the data amount can be reduced.

Further, in an exposure process using a laser beam, since the amount of data to be handled is small and a hologram of a certain size can be produced by one exposure, a highly accurate hologram can be easily produced in a short time. Becomes

On the other hand, since the reduced image forming system is used as the image forming system, even if the spatial light modulating element 2 having a coarse resolution is used, the object light can be expressed with a higher resolution than the spatial light modulating element 2. A hologram having a sufficiently fine change in interference fringe pattern can be manufactured.

Further, since a spatial light modulator capable of modulating the amplitude (intensity) distribution of transmitted light is used as the light shielding means 4, the light shielding area can be changed arbitrarily. Can be selectively transmitted.

(Second Embodiment) FIG. 4 shows a CGH for realizing a hologram manufacturing method according to the present embodiment.
FIG. 2 is a schematic diagram illustrating a configuration example of a manufacturing apparatus, in which the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted; only different components will be described here.

That is, in the present embodiment, as shown in FIG. 4, the reference light 1B shown in FIG. 1 is made incident on the surface of the photosensitive material 5 through the second lens 32 constituting a part of the imaging system. I have to.

Therefore, in the present embodiment, by making the reference beam 1B incident through the second lens 32, it is possible to easily configure the apparatus even when the focal length f2 of the second lens 32 is short. For example, the range of choices for the lens system and the like of the apparatus is increased, an imaging system with a high reduction ratio can be easily realized, and the apparatus can be downsized.

(Third Embodiment) In the present embodiment,
In the first or second embodiment, if the frequency component of the phase and / or amplitude distribution by the spatial light modulator 2 has a large width as a result of the distribution calculation by the computer, the phase and / or amplitude distribution is changed. A distribution is created for each of a plurality of small frequency bands, interference fringes are recorded for each of these frequency bands, and all of the frequency bands are subjected to multiple exposure.

Therefore, in the present embodiment, when the diffraction pattern is more complicated and a desirable light component and another component overlap (the frequency component of the phase and / or amplitude distribution by the spatial light modulator 2 is large). In addition, the modulation pattern of the spatial light modulator 2 is divided into modulation patterns of several frequency bands, and the modulation pattern of one frequency band is used for one exposure, and By sequentially exposing the light, the desired interference fringe pattern can be obtained on the photosensitive material 5 as a result.

That is, if the frequency of the modulation pattern of the spatial light modulator 2 has a certain width, the desired light distribution is broadened on the Fourier plane, and the frequency of the modulation pattern of the spatial light modulator 2 is narrow. If it is limited to the range, it takes advantage of the fact that the desired light distribution on the Fourier plane becomes a "point".

(Fourth Embodiment) In this embodiment,
In the first or second or third embodiment,
The photosensitive material 5 is placed on an XY stage or the like, and by controlling the XY stage or the like, the photosensitive material 5 is moved in the plane of the photosensitive material.

Therefore, in the present embodiment, a plurality of holograms are placed on the photosensitive material 5 by appropriately changing the exposure position on the photosensitive material 5 by placing the photosensitive material on an XY stage or the like and controlling the XY stage or the like. , It is easy to produce a large-sized hologram.

[0075]

As described above, according to the method and apparatus for producing a hologram of the present invention, the amount of calculation on a computer is reduced, and a hologram for reproducing a high-precision arbitrary wavefront in a short time is obtained. In addition to being able to be easily manufactured, even if the phase and / or amplitude modulation by the spatial light modulator is insufficient, it is possible to accurately manufacture a hologram having a desired interference fringe pattern. Become.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration example of a CGH manufacturing apparatus for realizing a hologram manufacturing method according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an example of light distribution on a Fourier plane in an imaging system and a corresponding light-shielding pattern of a light-shielding unit according to the first embodiment.

FIG. 3 is a spatial light modulator 2 according to the first embodiment.
The figure which shows an example of the upper phase distribution (when producing the plane wave inclined in X direction).

FIG. 4 is a schematic diagram showing a configuration example of a CGH manufacturing apparatus for realizing a hologram manufacturing method according to a second embodiment of the present invention.

[Explanation of symbols]

 1A: laser light, 1A ': object light, 1B: reference light, 2: spatial light modulation element, 31: first lens, 32: second lens, 4: light shielding means, 5: photosensitive material.

Claims (13)

[Claims] 1. A method for producing a hologram for reproducing an arbitrary wavefront, comprising: calculating a phase and / or amplitude distribution on a hologram surface with respect to a desired reproduced wavefront by a computer; The distribution of the phase and / or amplitude calculated by the computer is given to the laser light as object light, and the distribution of the phase and / or amplitude of the object light by the spatial light modulating element is converted into an image by the imaging system. In the modulated object light, an image is formed while passing through a light shielding means that transmits only a desired light component disposed near the Fourier plane of the modulated object light and is incident on a photosensitive material for hologram recording. A method for producing a hologram, characterized in that an object beam and a coherent reference beam are made incident, and interference fringes are recorded by interference between the two. 2. The method for producing a hologram according to claim 1, wherein the light shielding means is arranged on a Fourier plane of a phase and / or amplitude distribution of a spatial light modulation element in the imaging system. A method for producing a hologram, comprising: 3. The method for producing a hologram according to claim 1, wherein the light shielding means transmits only a 0th-order diffracted light component determined by a cell structure of the spatial light modulator. How to make a hologram. 4. The method for producing a hologram according to claim 1, wherein the light shielding means transmits only a light component determined from a cell structure of the spatial light modulator and a result of distribution calculation by the computer. A method for producing a hologram, characterized in that: 5. The method according to claim 1, wherein
4. The method for producing a hologram according to claim 1, wherein a reduced imaging system is used as the imaging system. 6. The method according to claim 1, wherein
3. The method for producing a hologram according to claim 1, wherein a spatial light modulation element capable of modulating an amplitude distribution of transmitted light is used as the light shielding means. 7. The method according to claim 1, wherein
The method for producing a hologram according to claim 1, wherein the reference light is incident through the imaging system. 8. The method according to claim 1, wherein
The method for producing a hologram according to claim 1, wherein the photosensitive material is moved in a plane of the photosensitive material. 9. The method according to claim 1, wherein
The method for producing a hologram according to claim 1, wherein a liquid crystal display device is used as the spatial light modulator. 10. The method of manufacturing a hologram according to claim 1, wherein a liquid crystal display device is used as the light shielding unit. . 11. The method of manufacturing a hologram according to claim 1, wherein the distribution calculation by the computer results in a frequency of a phase and / or amplitude distribution by the spatial light modulator. When the component has a large width, the distribution of the phase and / or amplitude is divided into a plurality of small frequency bands to create a distribution, and the interference fringes are recorded for each of the frequency bands,
A method for producing a hologram, wherein all the frequency bands are subjected to multiple exposure. 12. An apparatus for producing a hologram for reproducing an arbitrary wavefront, wherein a distribution of a phase and / or an amplitude on a hologram surface with respect to a desired reproduction wavefront calculated by a computer is given to a laser beam, and an object beam is provided. A spatial light modulation element, a first lens disposed so that a front focal position coincides with an arrangement position of the spatial light modulation element, and a sum of a focal length of the first lens and its own focal length. A second lens disposed at a position opposite to the spatial light modulation element away from the first lens by a corresponding distance, and distributing a phase and / or amplitude distribution of object light by the spatial light modulation element; An imaging system for forming an image; and a light shielding unit that is disposed so as to coincide with a rear focal position of the first lens and a front focal position of the second lens, and that transmits only a desired light component. A hologram recording photosensitive element which is disposed so as to coincide with the rear focal position of the second lens, and into which the object light transmitted through the light shielding means and the reference light having coherence with the object light are respectively incident. A hologram manufacturing apparatus, comprising: a material; 13. The hologram manufacturing apparatus according to claim 12, wherein the reference light is made to enter through the imaging system.