JP2008197246A - Hologram creating method and hologram creating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a hologram creating method and a hologram creating apparatus where an image free from unevenness can be subjected to interlace recording at a high speed, and to achieve the increase of the productivity and the increase of the image in a hologram. <P>SOLUTION: An object beam Ob is expanded by a beam size expanding means BE, information for hologram recording is given to the object beam Ob by a spatial light modulator SLM10 performing division display in a plurality of image display areas, the object beam Ob is made into diffuse beams per divided image region by a diffusion screen D10 and a partition member, the diffusion beam per divided image area is emitted onto a recording medium Med for a hologram by a lens array L12 corresponding to each divided area as an object beam Ob with fixed spacing, a reference beam Rb is emitted from the back face of the recording medium Med for a hologram, so as to record the interference between the same and the object beam Ob with fixed spacing, the fixed spacing of the object beam Ob on the recording medium Med for a hologram is divided into a plurality of pitches, and, in accordance with the pitches, the recording medium Med for a hologram is moved, and interlace exposure in interference conditions is performed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hologram creating method and a hologram creating apparatus for performing interference recording of hologram recording information divided into object light and reference light on a hologram recording medium with laser light.

  Among hologram creation apparatuses, there is an apparatus that makes a pseudo-stereoscopic image based on an intentionally created image instead of using reflected or transmitted light from an object. As a configuration of such a hologram creating device, a spatial light modulator (SLM) that displays a part of an image by irradiating a light beam for object light, and a spatial light modulator and a recording medium Position changing means for changing the relative positional relationship. While changing the relative positional relationship between the spatial light modulation element and the recording medium by the position changing means, a part of the interference pattern (part of the image) with respect to a part of the recording medium is displayed by the spatial light modulation element. The hologram is created by irradiating the recording light beam and performing the operation of recording a part of the interference pattern on the recording medium a plurality of times.

  Conventionally, for example, a basic dot type hologram printer disclosed in Patent Document 1 is known as this type of hologram creating apparatus. Stereograms that record minute element holograms such as this printer along the vertical and horizontal directions are exposed with one element hologram, have vertical and horizontal parallaxes, and even if the distance between the hologram and the observation point is changed. Since the vertical magnification and the horizontal magnification coincide with each other, there is an excellent feature that the reproduced image is not distorted. However, since the number of element holograms to be recorded becomes enormous, there is a disadvantage that it takes a lot of preparation time. That is, for each dot exposure, movement stop, exposure, movement and stop are sequentially repeated to expose the element hologram. For example, when exposing an A4 size (210 × 297 mm) at an element hologram size of 1 mm. , 62370 times (= (210 mm × 297 mm) ÷ (1 mm × 1 mm)), approximately 60,000 exposures are required, and one exposure requires 0.5 seconds including vibration reduction waiting time Is calculated as 8.7 hours (= 62370 times ÷ 60 seconds / minute ÷ 60 minutes / hour × 0.5 seconds / time).

  On the other hand, Patent Document 2 discloses a hologram creation method in which a large number of element holograms are recorded at once without a reduction optical system. In this hologram production method, 3 × 4 images are displayed as partial images by the liquid crystal panel 1 which is a spatial light modulation element shown in FIG. 18, and the laser light is modulated when passing through the liquid crystal panel 1. Laser light including image information of the liquid crystal panel 1 passes through a lens array of 3 × 4 convex lenses (not shown). The mask 3 for determining the size of the element hologram and the photosensitive material 5 are arranged on the rear focal plane of the convex lens array, and the element hologram having the same interval as the display image interval and the same size as the opening 7 of the mask 3 is formed at a time. Twelve can be recorded. In this method, the next exposure is performed by shifting the photosensitive material 5 by the size of the mask opening 7 in order to record on the entire surface of the photosensitive material. In FIG. 18, 9 is a laser light source, 11 is a liquid crystal shutter, 13 is a half mirror, 15 is a diffusing screen, and 17 and 19 are flat reflector groups.

  Non-Patent Document 1 discloses a hologram creation method for recording 12 element holograms at a time. In this document, 3 × 4 images with different viewpoints are displayed on the liquid crystal panel 1 shown in FIG. 19, and the laser light that has passed through the liquid crystal panel 1 is modulated. Laser light including image information of the liquid crystal panel 1 passes through the lens array 21 made up of 3 × 4 concave lenses. The light passing through each concave lens is reduced and projected onto the photosensitive material 5 by an afocal reduction optical system in which two convex lenses 23 and 25 are combined. Here, the front focal position of the concave lens 25 and the photosensitive material surface form an imaging relationship of the reduction optical system. In this preparation method, in order to record on the entire surface of the photosensitive material, the photosensitive material 5 is shifted by a distance three or four times that of the element hologram, and the next exposure is performed. In FIG. 19, reference numeral 27 denotes a spatial filter composed of a combination of a lens and a pinhole.

  Furthermore, Patent Document 3 discloses a hologram creation method in which a partition plate is installed between a liquid crystal panel and a lens array, and noise reduction in the final hologram, which has been a problem of the conventional multi-element hologram, is achieved. That is, in this hologram production method, a plurality of images displayed on the spatial light modulation element 1 shown in FIG. 20 are used as object light, and the plurality of lenses are arranged corresponding to individual images included in the object light. The object light is irradiated onto the recording surface 5 together with the reference light through the lens array 21 and the reduction optical systems 23 and 25 for reducing the object light emitted from the lens array 21, and the object light and the reference are applied to the recording surface 5. Record the interference light with the light. A partition 27 that separates individual images from each other is provided between the spatial light modulator 1 and the lens array 21. The partition 27 is provided so that at least the collected images between the collected images of the spatial light modulator 1 and the lens array 21 do not overlap each other. Thereby, noise is reduced. In FIG. 20, 29 is a diffuser plate, 31 is a front focal plane of the reduction optical system, 33 is a spatial filter, 35 is a mask, and 37 is an afocal lens optical system.

JP-A-3-249686 JP 2001-183962 A JP 2003-167500 A "High-speed recording of full-parallax holographic stereograms by a parallel exposure system" (Publication name: Optical Engineering, Vol. 35, No. 6, pp. 1556-1559, June 1996))

However, as in Patent Document 2 and Non-Patent Document 1, a multi-element hologram that records a plurality of element holograms simultaneously is a 12-dot (4 × 3 dot matrix / head) head, and the exposure time is 1/12. Even so, it takes 0.7 hours (= 8.7 hours ÷ 12) to create one hologram. Nevertheless, since the image resolution is about 1 mm, the image is considerably rough. For example, in the case of an A4 size hologram, the viewing distance is usually close to about 50 cm. In that case, a roughness of 1 mm is noticeable.
In addition, the hologram production method disclosed in Patent Document 2 is a method for magnifying and projecting a large divided image of a liquid crystal panel onto a diffuser plate, and recording each divided image on a hologram recording medium through a mask having a plurality of dotted holes. Since recording is performed on the recording medium, there is a disadvantage that a gap is formed and recording that creates a gap is required, and thus noise tends to enter the image. In addition, because of the enlargement system, the dot size on the material tends to be large, and the final hologram has low resolution and low image quality. In addition, a long coherent laser light source is required.
Further, in the hologram creation method disclosed in the non-patent literature, what is recorded in the element hologram is a reduced image of the light source located at the front focal point of the concave lens and a convolution integral image of the spectrum of the image. Since the size is very small compared to the interval of the element holograms, when appropriate exposure is performed in consideration of the dynamic range of the photosensitive material, a gap exists, which causes the quality of the reproduced image to deteriorate.
Furthermore, in the hologram creating method disclosed in Patent Document 3, the object light (a plurality of images) emitted from the condenser lens array has a substantially uniform light intensity on the front focal plane 31 of the reduction optical system composed of lenses. After being diffused and reduced by the reduction optical system, it is incident on the front surface of the photosensitive material 5. However, since the lens system is used, each divided area of the front focal plane 31 is uniformly affected by the partition 27. The final hologram has low image quality because the vicinity of the partition becomes dark.

  The present invention has been made in view of the above situation, and provides a hologram creating method and a hologram creating apparatus capable of interlace recording an image without unevenness at a high speed, and thereby to achieve high productivity and high image quality of the hologram. And

The above object of the present invention is achieved by the following configuration.
(1) A method for creating a hologram in which a laser light source is divided into object light and reference light to perform interference recording,
The object light is enlarged by a beam diameter enlarging means, and hologram recording information is given to the object light whose beam diameter is enlarged by a spatial light modulation element that divides and displays a hologram recording image in a plurality of image display areas,
The object light given the information for hologram recording is diffused for each of the divided image areas by a diffusion screen and a partition member,
Irradiating diffused light for each of the divided image areas as object light having a constant interval on the hologram recording medium by a lens array composed of a plurality of lenses corresponding to each divided area,
Irradiating the reference light from the back of the hologram recording medium to record interference with the object light having a certain interval;
A hologram creation method for performing interlaced exposure in which a predetermined interval of object light on the hologram recording medium is divided into a plurality of pitches, and a relative position with respect to the hologram recording medium is moved according to the pitches to repeatedly record an interference state.

  According to this hologram creating method, the object light irradiated on the hologram recording medium is uniformly diffused by the diffusion screen, and a condensed image is formed in a predetermined region by the lens array including the partition member and the plurality of lenses. In addition, since a plurality of scattered object light groups divided at regular intervals are simultaneously moved and subjected to interlaced exposure, high-speed and uneven exposure is performed with a large number of dots.

(2) The hologram production method according to (1), wherein a mask arranged on the hologram recording medium is used to block light other than the object light at the focal position of the lens array.

  According to this hologram creating method, the light diffused by the diffusing screen passes through the mask after passing through the lens array, thereby preventing the intermixing of the scattered object lights that record the element holograms. Thereby, the generation of joints and boundaries on the hologram recording medium is suppressed, and a decrease in diffraction efficiency due to the incidence of unnecessary light at each element hologram position is also suppressed.

(3) The hologram creating method according to (1) or (2), wherein the reference light is irradiated only to the irradiation position of the object light having a constant interval by a lens array and a collimator lens.

  According to this hologram creation method, the reference light becomes parallel light that is irradiated only to the entire area of the object light exposure area by the lens array and the collimator lens, and the light use efficiency is improved.

(4) The hologram production method according to (2) or (3), wherein irradiation is limited only to a position where the object light limited by the mask for object light is irradiated by the reference light mask arranged on the reference light side. .

  According to this hologram creation method, the reference light irradiated only on the entire object light exposure area by the collimator lens is cut into a circle or a rectangle by the mask. As a result, the reference light size is optimized, mixing of adjacent reference light is prevented, fogging is suppressed, and a decrease in diffraction efficiency is also suppressed.

(5) The relationship between the number of divisions of the object light display area by the interlace exposure and the division pitch of the object light at regular intervals is (X, Y) = (aXn + 1, bXn + 1) (n is an integer of 1 or more)
Number of display areas of object light: (X, Y)
Division pitch of object light at regular intervals: a (X direction), b (Y direction)
The hologram production method according to any one of (1) to (4), wherein:

According to this hologram creation method, when the number of display areas of the object light is X and Y, the X direction and the Y direction of the element hologram are each (number of inter-element hologram feeds) × n + 1. Specifically, for example, 7 × 1 + 1 = 8, 7 × 2 + 1 = 15, 7 × 3 + 1 = 22... In the Y direction. If the element hologram is, for example, X, Y = 16, 8, X, Y = 15, 7 without using one column in the X direction and one column in the Y direction. In such interlaced exposure, the recording of the element holograms in the form of X, Y = 15,7 matrix can be moved at regular intervals over the entire surface of the recording medium, and the most efficient process that does not burden the apparatus is performed. be able to.
As the number of element holograms decreases from 16 to 15 when viewed in the X direction, the number of pixels used in one element hologram can be increased. Further, the number of pixels is not increased, and it may be used at the boundary between element holograms accordingly. In that case, since a predetermined pixel can be allocated among 15 element holograms in the X direction, there are advantages such as freedom in designing the partition member and wider tolerance for assembly errors.

(6) A hologram creating apparatus that divides a laser light source into object light and reference light and performs interference recording on a hologram recording medium,
Beam diameter expanding means for expanding the beam diameter of the object light;
A spatial light modulation element that divides and displays a hologram recording image in a plurality of image display areas and gives hologram recording information to the object light;
A diffusion and partition member that converts the object light from the spatial light modulator into diffused light for each of the divided image regions;
A lens array comprising a plurality of lenses corresponding to each divided castle and irradiating diffused light for each divided image region as object light having a fixed interval on a hologram recording medium,
A reference light optical system that irradiates the reference light from the back surface of the hologram recording medium and interferes with the object light having a constant interval;
A hologram production apparatus comprising: an interlace exposure unit that divides a predetermined interval of object light on the hologram recording medium into a plurality of pitches and performs a moving exposure process on a relative position with respect to the hologram recording medium according to the pitches.

  According to this hologram creating apparatus, the transmitted object light is uniformly diffused by the diffusion plate in the transmissive spatial light modulation element, and a condensed image is formed in a predetermined region by the partition member. In addition, the interlaced exposure means simultaneously moves a plurality of scattered object light groups that are divided at regular intervals, and performs exposure with a large number of dots at high speed and with reduced unevenness.

(7) The hologram production apparatus according to (6), further including a mask disposed on the hologram recording medium and having an opening for object light at a focal position of the lens array.

  According to this hologram creating apparatus, the light diffused by the diffusing screen is transmitted through the mask through the lens array, and unnecessary diffused light is cut when passing through the mask hole, and the scattered object light for recording the element hologram Mutual contamination is prevented. Thereby, the generation of joints and boundaries on the hologram recording medium is suppressed, and a decrease in diffraction efficiency due to the incidence of unnecessary light at each element hologram position is also suppressed.

(8) The hologram creating apparatus according to (6) or (7), wherein the reference light optical system includes a lens array and a collimator lens that irradiates only the irradiation position of the object light having a predetermined interval.

  According to this hologram creating apparatus, the reference light becomes parallel light that is irradiated only to the entire area of the object light exposure area by the lens array and the collimator lens, and the light use efficiency is improved.

(9) The above (7) or (8), wherein the reference light optical system includes a reference light mask having an opening for irradiating the reference light at a position irradiated with the object light limited by the object light mask. The hologram production apparatus described in 1.

  According to this hologram creating apparatus, the reference light irradiated only on the entire object light exposure area by the collimator lens is cut into a circle or a rectangle by the mask. As a result, the reference light size is optimized, and fogging caused by mixing of adjacent reference light is suppressed.

  According to the hologram creating method of the present invention, the object light to which the hologram recording information is given is diffused for each divided image area by the diffusion screen and the partition member, and the diffused light for each divided image area is an object having a constant interval. In addition to irradiating as a light, the interlaced exposure is performed in which a certain interval of the object light is divided into a plurality of pitches, the hologram recording medium is moved according to the pitches, and the interference state recording is repeated. The object light to be diffused uniformly forms a condensed image in a predetermined area by the partition member, and no gap or overlap occurs in the condensed image. In addition, since a plurality of scattered object light groups divided at regular intervals move simultaneously, high-speed exposure can be performed with a large number of dots. As a result, high-speed and non-uniform images can be recorded in an interlaced manner, and high productivity and high image quality of the hologram can be achieved.

  According to the hologram creating apparatus of the present invention, the beam diameter enlarging means for enlarging the object light, the spatial light modulation element for dividing and displaying the hologram recording image in a plurality of image display areas, and the object light from the spatial light modulation element A diffusing and partitioning member for diffusing light for each divided image area, and an interlace exposure means for dividing a predetermined interval of object light on the hologram recording medium into a plurality of pitches and moving and exposing the hologram recording medium according to the pitches In the transmissive spatial light modulator, the transmitted object light is uniformly diffused by the diffusion plate, and a condensed image is formed in a predetermined area by the partition member, and a gap or an overlap occurs in the condensed image. Absent. In addition, since a plurality of scattered object light groups divided at regular intervals move simultaneously by the interlace exposure means, high-speed exposure can be performed with a large number of dots. As a result, high-speed and non-uniform images can be recorded in an interlaced manner, and high productivity and high image quality of the hologram can be achieved.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of a hologram creating method and a hologram creating apparatus according to the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram of a hologram creating apparatus according to an embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the same member in each following figure, and the overlapping description is diverted. In this specification, the light propagation direction is referred to as the front side, and the opposite direction is referred to as the rear side.

  The hologram creating apparatus 100 according to this embodiment includes a laser light source LS, shutters S1, S2, and S3, optical attenuators ND1, ND2, and ND3, λ / 2 wavelength plates λ / 2-1, λ / 2-2, and λ /. 2-2, light splitting means PBS1, PBS2, PBS3, multiplexing means DM1, DM2, DM3, DM4, mirrors M1, M2, M3, M4, beam expander BE, spatial light modulator SLM10, diffusion plate D10, partition wall PA The interlace exposure means 110 is configured with the mask MS, the microlens array L12 and the like as main members.

  As the laser light source LS, a plurality of colors of R laser LS1, G laser LS2, and B laser LS3 are provided. The object light Ob emitted from the laser light source LS will be described later. As an outline of the optical system, first, the optical system is enlarged by the beam expander BE, the spatial light modulation element SLM10, the diffusion plate D10, the partition member (partition wall) PA, The light passes through the microlens array L12 and the mask MS in order, and is irradiated onto the hologram recording medium Med. Further, the reference light Rb is enlarged by the reference light optical system and irradiated on the back surface of the hologram recording medium Med.

  Here, the light source LS is set as a plurality of light sources, and a laser light source in the visible range of 380 to 700 nm having coherence is applied. Even if the light source does not have coherence, the coherence can be improved by performing a band narrowing treatment such as etalon. As the type of laser, a semiconductor laser, a solid-state laser including semiconductor excitation (DPSS), another solid-state laser, a gas laser such as an argon laser, or a liquid laser such as a dye laser can be used. Further, a laser in which a harmonic generator (SHG, THG, etc.) is incorporated in these lasers may be used.

Examples of the wavelength type CW of the laser light source LS include the following.
[Semiconductor] 405, 408, 622, 635, 650, 670
[He-Cd] 442
[DPSS] 447, 457, 473, 491, 514, 527, 532, 561, 671
[Ar] 488, 515
[He-Ne] 633
[Krypton] 413, 407, 647, 676
[Ruby (solid)] 690
In this embodiment, 473, 532, and 647 nm are used.

The wavelength of the laser light source LS includes the following types and pulses.
[Zebra made]
1. 1. Diode pump solid state laser, strobe pump solid state laser, dye laser Ruby, Sapphire, Garnet, Alexandrite, Titanium Sapphire (Ti: Sapphire), Neodium: Yttrium Aluminum Garnet (Nd: YAG), Neodium: Yttrium Lithium Fluoride (Nd: YLF)
3. Optical parametric oscillators (OPOs) tune from 410 to 690 nm from 355 nm, which is the third harmonic of Nd: YAG laser.
From 4.898nm and 1256nm OPO through SHG (2nd harmonic) 449nm and 628nm

[Geola]
1. Nd: YLF 1313 nm, SHG 656.3 nm, THG 437.7 nm
Mainly used as RB.
2. Nd: YLF1047.1nm, SHG523.6nm
Mainly used as G.
3. Nd: YLF1053nm, SHG526.5m
4). Nd: YAG1064.2nm, SHG532.1nm
5. Nd: YAG1318.8nm, SHG659.4nm, THG439.6nm
6). Nd: YAG 1338nm, SHG669nm, THG446nm
7). Nd: YAP1064.3nm, SHG532.2nm
8). Nd: YAP1079.6nm, SHG539.8nm
9. Nd: YAP 1099 nm, SHG 549.5 nm
10. Nd: YAP 1341.4 nm, SHG 670.7 nm, THG 447.1 nm
11. Nd: BEL 1070nm, SHG535nm
12 Nd: BEL1351nm, SHG675.5nm, THG450.3nm
13. 532: DPSS
14 690: Ruby (solid)
15. 628nm and 443nm

  Now, in the optical system provided with the object light Ob, the light emitted from the lasers LS1, LS2, and LS3 enters the shutters S1, S2, and S3. The shutters S1, S2, and S3 are not limited to the mechanical type, and may be any one such as an acoustooptic device (AOM, AOD) or a liquid crystal shutter as long as it can control [passing] / [blocking] of transmitted light. The shutters S1, S2, and S3 are desirably installed for each laser LS1, LS2, and LS3. For stable oscillation, the lasers LS1, LS2, and LS3 are preferably always driven to be ON. Therefore, the transmission light from the lasers LS1, LS2, and LS3 is [passed] / [blocked] controlled by opening and closing the shutters S1, S2, and S3.

  Optical attenuators ND1, ND2, and ND3 are provided at the light traveling direction positions of the shutters S1, S2, and S3. The light splitting means PBS1, PBS2, and PBS3 are not necessarily required when the output can be adjusted by the laser light source LS. Since there is a laser light source LS without a power adjustment function, the power of each laser LS1, LS2, LS3 can be adjusted, and can be used, for example, to finely adjust the color balance of the hologram.

  Half-wave plates (λ / 2 wavelength plates) λ / 2-1, λ / 2-2, and λ / 2-2 are provided at the light traveling direction positions of the optical attenuators ND1, ND2, and ND3. The λ / 2 wavelength plates λ / 2-1, λ / 2-2, and λ / 2-2 have a half-wavelength optical path difference (180 ° phase difference) between orthogonal linearly polarized light components of incident light waves. give.

  The linearly polarized light components emitted from the λ / 2 wave plates λ / 2-1, λ / 2-2, and λ / 2-2 enter the light splitting means PBS1, PBS2, and PBS3. In the present embodiment, a polarization beam splitter is used as the light splitting means PBS1, PBS2, PBS3. According to the polarization beam splitter, light loss can be reduced, and the linearly polarized light component can be efficiently divided into the object light Ob and the reference light Rb. The polarization beam splitter can be arbitrarily changed in spectral ratio by combining with the preceding λ / 2 wavelength plate. Further, as the light splitting means PBS1, PBS2, PBS3, half mirrors may be used. In addition, a wedge glass on which a metal film is deposited may be used. In this case, the division ratio can be changed by changing the type and thickness of the metal curtain.

  The object light Ob and the reference light Rb split by the light splitting means PBS1, PBS2 and PBS3 enter the multiplexing means DM1, DM2, DM3 and DM4 for aligning the optical axes of the respective wavelengths. Here, a dichroic mirror (cube) is used as the multiplexing means DM1, DM2, DM3, DM4. The dichroic mirror has little optical loss and can efficiently overlap the optical axes. Further, as the multiplexing means DM1, DM2, DM3, DM4, a half mirror or other optical member with an optical action film can be used.

  The light split by the light splitting means PBS1, PBS2, PBS3 is introduced into the multiplexing means DM1, DM2, DM3, DM4 by the mirrors M1, M2, M3, M4, and the respective lights of the object light Ob and the reference light Rb. It can be adjusted to the axis.

  A beam diameter expanding means (beam expander) BE for expanding the beam diameter is provided at a position in the light traveling direction of the multiplexing means DM2 for the object light Ob. The beam expander BE includes a first lens L10, a pinhole P10, and a second lens L11. Usually, the diameter of the laser beam emitted from the laser light source is about 0.1 to 5 mm. The beam expander BE expands the beam diameter so that this is irradiated to the entire area of the later spatial light modulator SLM10.

  As the first lens L10, a lens having a positive power is normally used, and light that is focused once and then diverges is used. Normally, a general objective lens used in a microscope or the like is used for the first lens L10. A comparatively high magnification objective lens is used to expand the beam at a short distance in the optical axis direction. Here, a lens with a magnification of 40 to 50 times can be preferably used. Further, it is preferable to use a lens such as an achromatic lens that has a small focal position change (small chromatic aberration) even when the wavelength is different.

  The pinhole P10 is not used in the normal beam expander BE, but in this embodiment, since it is used for later optical interference, it is necessary to clean the beam quality. For this purpose, a circular pinhole of φ20 to 50 μm is installed at the focal position of the first lens L10. These combinations of the first lens L10 and the pinhole P10 are particularly referred to as a spatial filter SF. The spatial filter SF is an effective means for removing irregular fluctuations from the intensity distribution of the laser beam.

  The intensity of the laser beam varies due to scattering caused by minute defects in the optical components or minute particles in the air. This can be confirmed by enlarging the laser beam on the card (a part of an ideal pattern in which speckles are uniformly distributed, or a spiral pattern or ring generated on the pattern is spatial noise). . A collimated ideal coherent laser beam exhibits characteristics as if emitted from a point light source at a distance. When performing spatial filtering, it is necessary to focus the beam and generate a “light source” image with all defects on the optical path defocused on the beam periphery. Most are blocked by the pinhole P10.

  A second lens L11 is provided at the position of the pinhole P10 in the light traveling direction. The second lens L11 is a collimator lens having a focal length f that converts divergent light into parallel light. A lens having a positive power is used as the second lens L11. Further, it is preferable to use a lens such as an achromatic lens that has a small focal position change (small chromatic aberration) even when the wavelength is different.

A transmissive spatial light modulation element SLM10 for placing image information as a hologram on the spread object light is provided at a position in the light traveling direction of the beam expander BE. This spatial light modulation element SLM10 is, for example, an electrical address type spatial light modulator, which is composed of a liquid crystal display or the like, and modulates the light intensity (amplitude) of the incident plane wave, which is the spread object light, for each pixel. Then, the image information is carried and transmitted. The display image of the spatial light modulation element SLM10, that is, the output light image from the spatial light modulation element SLM10 can be changed by changing the transmittance of each pixel. Thereby, image processing according to the exposure position is performed.
The display of the spatial light modulator SLM10 is divided and displayed in the form of a matrix in which the same shape is continuously arranged, and is displayed separately as a plurality of image display areas. In the case of the present embodiment, as an example of this matrix, the X direction is 34.816 mm (= 16 × 2.176 mm), the Y direction is 17.408 mm (= 8 × 2.176 mm), and the like.

Here, FIG. 2 is an enlarged configuration diagram showing the configuration from the spatial light modulator to the recording medium.
A diffusion screen (diffusion plate) D10 serving as a screen for projecting an image including image information is provided at a position in the light traveling direction of the spatial light modulator SLM10. As the diffusing plate D10, any material that transmits or reflects light in the visible light region and diffuses light can be used. Preferably, the surface of a plate material such as plastic or glass is rough in a ground glass shape. More preferably, it is made of optical glass having a small light polarization property, and only one surface is ground glass. As for the degree of frosted glass, those having sand numbers # 240 to # 3000 are appropriately used. A transmittance of 10 to 95% is appropriately used. The light emitted from the diffusing plate D10 enters the lens array L12.
In particular, in the case of the transmissive spatial light modulator SLM10, it is simplest and low cost to directly attach the diffusion plate D10 to the spatial light modulator SLM10.

  A lens array L12 is provided at a position in the light traveling direction of the diffusion screen (diffusion plate) D10. The lens array L12 includes a plurality of lenses corresponding to each of the divided image display areas of the spatial light modulator SLM10, and includes a lens group having a focal length f2 having a positive lens power. Each lens is involved in recording in each element program described later. Manufactured by batch molding or adhesive method. In the case of an optical magnification of 1 time, a pitch of about 2.176 mm (= 256 pixels * 8.5 μm) is appropriate from the correspondence with the spatial light modulator SLM10. The larger the NA, the wider the viewing angle of the finally created hologram, and the higher the quality of the hologram. Further, as the focal length f2, specifically, F = 1 to 5 mm is appropriate, and preferably F = 1 to 3 mm.

A partition member (partition wall) PA is provided in parallel with the optical axis in front of the lens array L12 at the position in the light traveling direction of the diffusion plate D10. As described above, the partition wall PA is disposed for the purpose of shielding light so that the image information divided and displayed in the plurality of image display areas by the spatial light modulation element SLM10 does not go to other divided areas. It is provided corresponding to the boundary of the image display area.
The thickness of the partition wall PA is at least 50 μm, preferably 100 μm or more in terms of strength. When the optical magnification is “1”, for example, 56 pixels out of 256 pixels are not used on the spatial light modulation element SLM made by SONY, which will be described later. However, 200 pixels of effective pixels are shielded from light due to a manufacturing error or the like. Therefore, about 300 μm or less is preferable (same in terms of strength).

  The light shielding performance of the partition wall PA is such that the light attenuation in the vertical direction in the visible light region is 1/10 or less, preferably 1/100 or less. The lens-side tip shape is preferably a shape fitted to the concave shape of the lens array L12. In the lens array L12, a central portion of each divided region is convex, and a boundary portion of each divided region is a concave portion. A shape that fits into the recess is preferable. As a result, it is structurally strong and resistant to vibration, the waiting time for vibration suppression when vibration occurs in the optical system is shortened, and printing can be made shorter. Since the length of the partition wall PA is provided between the diffuser plate D10 and the lens array L12, the partition wall L12 having a length matching the back focus value of the lens array L12 is abutted (pinched) without adjusting the position in the optical axis direction. ) Method, the diffusion plate D10 and the lens array L12 can be assembled. In this case, the rigidity of the optical system is also increased. Also, black is desirable for the purpose of preventing multiple reflections.

A mask MS is provided between the microlens array L12 and the recording medium Med, that is, in the vicinity of the recording medium Med and at a non-contact position. The mask MS is located at the focal position of the lens array L12, and has an aperture hole ho for object light corresponding to each lens. A pitch of about 2.176 mm (= 256 pixels * 8.5 um) is appropriate as the pitch of each focal position from the correspondence with the spatial light modulator SLM10 and the lens array L12.
The light shielding mask MS is preferably installed in the vicinity of the focal position after the focal position of the lens array L12. This is for transmitting a part of the light diffused by the diffusion plate D10. The size w1 of the hole ho of the mask MS is preferably smaller than the element hologram size w2 (≈exposure pitch). The shape of the hole ho is preferably the same as that of the element hologram, and is usually rectangular. Alternatively, in order to make it difficult to recognize joints and boundaries on the hologram and prevent unevenness, a parallelogram or rhombus is desirable.

  A predetermined gap Dis is provided between the mask MS and the hologram recording medium Med so as to be non-contact. This is because the positional relationship between the mask MS and the recording medium Med relatively moves during hologram recording, and since the film surface of the recording medium Med is normally on the mask MS side, the film contacts the film when moving. This is to avoid scratches. However, if this gap Dis is too large, blurring is undesirably increased, so an appropriate value for the gap Dis is 0.1 to 2 mm, and more preferably 0.2 to 0.5 mm.

  As can be seen from the configuration shown in FIG. 2, the light diffused by the diffusing plate D10 passes through the mask MS through the lens array L12, and unnecessary diffused light is cut when passing through the mask hole ho. Mutual mixing of scattered object lights to be recorded is prevented. As a result, the generation of joints and boundaries on the hologram recording medium Med is suppressed.

According to the hologram creating apparatus 100 configured as described above, the object light transmitted through the transmissive spatial light modulator SLM10 is uniformly diffused by the diffusion plate D10 and a condensed image is formed in a predetermined region by the partition wall PA. To do. Further, the interlaced exposure means 110 simultaneously shifts the relative positions of the plurality of scattered object light groups divided at regular intervals from the recording medium Med, and performs interlaced exposure, which will be described later, to perform high-speed exposure with a large number of dots. And a hologram is created by generating interference with reference light described below.
The recording medium Med is arranged so that the recording film surface is on the mask MS side. This is because when the object light transmitted through the mask MS reaches the recording film after passing through the transparent support of the recording medium Med, the light affected by the polarization-dependent characteristics of the transparent support reaches the film. This is because defects such as image unevenness may occur.

Next, an optical system for reference light will be described.
A reference light mirror M20 is provided at the light traveling direction position of the above-mentioned combining means DM4 for the reference light Rb. Further, the reference light mirror M20 is configured as a reference light beam expander by sequentially arranging a lens L20, a pinhole P20, and a lens L21 at a position in the light traveling direction.

  The reference light mirror M20 is preferably a mirror that does not affect the polarization state of light. The surface treatment preferably forms an antireflection curtain having a good antireflection function in a wide range of visible light without forming a strong antireflection film at a specific wavelength. The lens L20 corresponds to the first object light lens L10, the aperture (pinhole) P20 corresponds to the object light aperture (pinhole P10), and the lens L21 corresponds to the second object light lens L11. This has the same function as the beam expander BE for object light.

  A reference light final mirror M21 is disposed at the position of the lens L21 in the light traveling direction. The reference light final mirror M21 is a mirror that deflects (directs) the reference light toward the recording medium at a predetermined angle. Usually, the reference light Rb is irradiated onto the recording medium Med at 45 degrees. Alternatively, it is most preferable to irradiate at a Brewster angle of 58 degrees (55 to 60 degrees) with the least reflection with respect to the normal line of the recording medium Med. For example, the Brewster angle of visible light incident on glass having a refractive index of 1.5 from the air having a refractive index of 1 is about 56 degrees. The refractive index changes with wavelength, but the change is not so great. For example, the difference between ultraviolet light and infrared light is about 0.01.

  It is desirable that the size of the reference light Rb reflected by the reference light final mirror M21 is irradiated with uniform illuminance over the entire area of the object light exposure area of the hologram recording medium Med. In order to effectively use the light amount and prevent fogging, the lens L21 creates a beam diameter of a size that can be irradiated on the entire area of the object light exposure area, effectively uses the light amount, and then installs a mask or the like, thereby providing the lens L21. The cross section of the light beam reaching the final mirror for reference light M21 from may be cut from a circle to a quadrangle, and fogging can be prevented with such a configuration.

Next, the reference light can be configured to irradiate only the vicinity of the focal point of the reference light Rb, in addition to the uniform illuminance over the entire area.
FIG. 3 is a configuration diagram in the case of multi-reference light, and FIG. 4 is an enlarged view of a main part of FIG.
Collimator lenses (reference light lens arrays) L22 and L23 are arranged in the light traveling direction position of the reference light final mirror M21. The collimator lenses (reference light lens arrays) L22 and L23 are arranged so as to correspond to the pitch of the microlens array L12 in the object light optical system. The incident angle to the hologram recording medium Med is determined in advance in order to extract the interference state. In the case of this embodiment, it is necessary to change the pitches in the X direction and the Y direction with respect to the optical axis immediately before the material. Specifically, in the case of θ = 58 inclination, the X direction is about 2.176 mm and does not change, but the Y direction is 1.185 mm (= 2.176 × cos 57 degrees), which is about half.

  Further, the reference light size also does not change in the X direction of about 0.4 to 1.0, preferably 0.4 to 0.6 mm, but the Y direction is 0.22 to 0.55 mm, preferably 0.22 to 0.26 mm. A rectangle that is approximately half, such as 0.33 (= X size × cos 57 degrees), is preferable. The reference light Rb is preferably parallel light. As one of the methods, in the design of the second-stage lens array L23, it is possible to change either or both of the lens power and the focal length in the Y direction from the X direction.

  As described above, it is more efficient to direct the reference light Rb to the exposure positions at a plurality of object light focal positions rather than uniform exposure. This is because when the reference light Rb is irradiated on a region other than the object light Ob on the hologram recording medium Med, the hologram recording medium Med in that region is exposed, which causes fogging, This is because the amount of light for essential interference is reduced.

  In addition, in such exposure at a plurality of object light focal positions, light in a region other than that irradiated with the object light Ob is guided to the region irradiated with the object light Ob as much as possible to reduce light loss, and the object light Ob. In order to maintain the exposure balance near the irradiation boundary, it is preferable to use parallel light. Further, by setting the reference light Rb having a size slightly larger than one object light size, each object light can be covered even if there is a slight positional deviation. In the present embodiment, since the object light size is 0.3 mm, each reference light size is preferably 0.4 to 1.0 mm. More preferably, 0.4 to 0.6 mm is good.

  Further, as described above, the reference light size to the reference light lens array L23 is the minimum, X direction 34.816 mm (= 16 × 2.176 mm), Y direction 17.408 mm (= 8 × 2.176 mm). ), But if the Y direction is set to 9.481 mm (= 17.408 × cos 57 degrees), energy can be used more efficiently. Specifically, this can be achieved by appropriately selecting the lens L20, or by appropriately selecting a cylindrical lens having refractive power only in the X direction having a different focal length and a cylindrical lens having refractive power only in the Y direction. . The front sectional shape of the lens array L23 for one division may be a rectangle.

Next, as another embodiment of the optical system of the hologram creating method and the hologram creating apparatus according to the present invention, there is a form using a reflective SLM.
FIG. 5 is a configuration diagram showing an example of an optical system for creating a hologram using a reflective SLM.
The hologram creating apparatus 100 according to the present embodiment uses a reflective spatial light modulator SLM11 instead of the transmissive spatial light modulator SLM10 shown in FIG. In general, in the case of a reflective type, it is an important factor that a high-speed response is achieved. As such a reflective spatial light modulator SLM11 having a high response speed, for example, a reflective LCOS, 4K2KD-ILA, 4096 × 2160 pixel manufactured by Victor Corporation can be used.

  As the configuration, first, the configuration from the laser light source LS of the optical system of the embodiment shown in FIG. 1 to the second lens L11 of the beam expander BE is the same. Then, the light splitting means PBS4 is disposed at the position of the second lens L11 in the light traveling direction, and the object light Ob polarized by the light splitting means PBS1, PBS2, PBS3 is reflected. The object light Ob is reflected by the reflective SLM 11 disposed on one exit surface of the light splitting means PBS4, and information as a hologram is written at that time, and is incident on the light splitting means PBS4 again, and the polarization direction is aligned. As it is, it passes through as it is.

A third lens L13 having the same focal length f1 as that of the second lens L11 is provided at a position facing the reflective SLM 11 and in the light traveling direction from the light splitting means PBS4. The focal length f1 preferably takes the following values.
Focal length f1 = f1a + f1b
f1a: distance from the second lens L11 to the optical axis reflection position of the light splitting means PBS4
f1b: Distance from the optical axis reflection position of the light splitting means PBS4 to the reflection type SLM11 A diffusing plate D10 is disposed at a position twice the focal length f1 from the third lens L13, and the light traveling direction positions thereafter are shown in FIG. 1 and the lens array L12 and the partition member (partition wall) PA are arranged close to the recording medium. As described above, an optical system that forms an image at 1: 1 is the simplest and can be easily set.

Next, regarding a hologram creating method and a hologram creating apparatus using the reflective SLM according to the present invention, a configuration including a reduction optical system instead of a 1: 1 optical system will be described.
FIG. 6 is a modification of FIG. 5 and is a configuration diagram using a reduction optical system.
5 is longer than the focal length f1 of the second lens L11 at the position in the light traveling direction from the light splitting means PBS4 at the position facing the reflective SLM11 with respect to the position of the light splitting means PBS4 and the reflective SLM11 shown in FIG. A third lens L15 having a focal length f5 is provided. Further, a fourth lens L16 having a focal length f6 shorter than the focal length f5 is provided at the position of the third lens L15 in the light traveling direction. The fourth lens L16 is disposed at a position obtained by adding the focal length f6 and the focal length f5, and forms a reduction optical system.

The lens array L12 and the partition member (partition wall) PA are arranged in the vicinity of the recording medium with the same configuration as in FIG.
In this way, by adopting a configuration in which the reduction / enlargement system can be arbitrarily set, it is possible to reduce restrictions on the design of the lens array L12 and the drive system in the light traveling direction position.

As the reflective spatial light modulator SLM11, in addition to the above, an SXRD device, 4K SXRD, which is a reflective liquid crystal device LCOS (Liquid Crystal on Silicon) using a silicon driving element manufactured by Sony, is preferably used. Can do. The specifications are listed below.
Display size Square 1.55 type Number of pixels 8.85 million pixels (4096H x 2160V)
Pixel pitch 8.5μm
Space between pixels 0.35μm
Liquid crystal mode Vertical alignment liquid crystal cell thickness 2μm or less (1.5-2μm)
Alignment film Inorganic alignment film Device contrast 4000: 1
Response speed (τ on + τ off) Less than 5 ms Reflectance (550 nm ± 35 nm) 72%
Backplane process 0.35μm (partially 0.25μm) MOS process

  Here, the parallax required for the hologram is about 200 parallaxes in the left-right direction, and in this case, a smooth parallax image can be observed. In this configuration, a hologram (full parallax hologram) having a parallax also in the vertical direction can be produced, so the vertical direction is also set to 200 parallaxes. It is sufficient that at least one pixel on the SLM corresponds to one parallax. In other words, as one element hologram, the number of pixels required for the SLM is a total of 40000 pixels of 200 pixels in the X direction and 200 pixels in the Y direction.

  If the effective size of one divided lens array is 80%, the size of the lens corresponding to one element hologram is 250 (= 200 ÷ 0.8) pixel. Considering the ease of control digitally, it is preferable to divide in units of 256 pixels. If the reflection type spatial light modulation element SLM11 of 4096 × 2048 pixels is divided into 256 × 256 pixels, it can be divided into 16 × 8 = 128 element holograms (previously, 4 × 3 12 pieces). As a result, a variable optical system can be configured, and it becomes possible to cope with the overall dimensional difference of the lens array L12.

  In the reference light optical system, as shown in FIG. 6, a mask MS may be provided at the position of the lens L21 in the light traveling direction, and an image of the mask MS portion may be formed by an additional optical system. As a result, accurate imaging can be performed in the irradiation range of the object light reduced by the reduction optical system, and the viewing angle can be widened.

Next, a hologram creation method using the hologram creation apparatus 100 of the above embodiment will be described.
FIG. 7 is a schematic diagram showing a basic arrangement of divided element holograms basically determined by a spatial light modulation element and a lens array.
In this hologram production method, an exposure method without gaps is performed. That is, in the configuration of the embodiment of the present invention, object light having a width of 0.3 mm is 16 in the X direction, 8 in the Y direction, and 128 in total in the Y direction by the spatial light modulation element and the lens array. The object light beams are scattered with a gap therebetween to form a divided element hologram group.

  It is necessary to perform exposure without gaps using the scattered object light (spot). Moreover, it is best to perform the feeding at a constant feeding pitch (that is, it is preferable that the recording medium Med is fed back and forth so that the feeding speed does not pulsate).

As described above, the segmented element hologram group is composed of segmented element holograms of X, Y = 16 columns and 8 rows.
Element hologram X-direction size: 0.3 mm
Dividing element hologram X-direction pitch: 2.176 mm
Dividing element hologram Y-direction pitch: 2.176 mm
Dividing element hologram [group] Pitch in X direction: 34.816 (= 2.176 × 16)
Dividing element hologram [group] Y-direction pitch: 17.408 (= 2.176 × 8).

FIG. 8 is a schematic diagram showing a situation where the scattered object light having the basic arrangement shown in FIG. 7 is moved in the X direction and exposed without a gap.
In the present embodiment, the split element hologram X-direction pitch and the Y direction are based on the split element hologram having the above basic arrangement created by the spatial light modulation element and the lens array of the optical system shown in FIGS. The relative position with respect to the hologram recording medium Med is moved according to the pitch, and the recording in the interference state is repeated on the hologram recording medium Med. At this time, at the time of exposure, the moving operation is stopped in order to avoid the deviation of the interference fringes having a pitch of submicron order. The image on the spatial light modulation element SLM10 is changed for each exposure.

In a situation where the scattered object light of the basic array is actually moved in the X direction and exposed without gaps, the following occurs.
Basic form-X-direction movement: Substantially element hologram size X-direction feed number (the number of feeds in the divided element hologram [group], hereinafter referred to as (small) for convenience)
: 7 times ≒ 2.176 / 0.3 (integer)
X direction feed pitch (small)
: 0.311 mm ≒ 2.176 mm / 7 times Actually, since there is a slight gap, the element hologram X direction size is set to 0.32 mm, the X direction feed number (small) is 1 time, and many times 8 times Or 0.272 mm (= 2.176 mm / 8 times).

The movement of the coordinates (1, 1) will be described as a representative of the X-direction movement process.
The optical unit or the recording medium Med moves relatively.
1.1) Move in the X direction from 1) to 2), move in the X direction feed pitch (small) (0.311 mm) Move in the X direction from 2) to 3) move in the X direction feed pitch (small) (0.311 mm) 3.3 Move from 3) to 4) in the X direction, move in the X direction feed pitch (small) (0.311 mm) Move to the X direction from 4.4) to 5) move in the X direction feed pitch (small) (0.311 mm) 5.5) Move to X) in the X direction, X direction feed pitch (small) (0.311 mm) move to 6.6) to 7) Move in the X direction to X direction feed pitch (small) (0.311 mm) 7.7) to 8) in the X direction, X direction feed pitch (large) (32.950 mm)
= 34.816 mm−6 times * 0.311 mm) Movement By repeating these steps, exposure can be performed without gaps in the X direction.
After the exposure of the desired exposure width is completed, the coordinates (1, 1) return to the position of the original coordinates (1, 1) only in the X direction.
Next, since there is a gap in the Y direction, the next exposure is repeated.

FIG. 9 is a schematic diagram in which the exposure shown in FIG. 8 is developed in the Y direction.
Basic form-Y-direction movement: Approximately element hologram size Y-direction feed number (small): 7 times ≒ 2.176 / 0.3 (integer)
Y direction feed pitch (small): 0.311 mm ≒ 2.176 mm / 7 times

The movement of the coordinates (1, 1) will be described as the Y-direction movement process.
The optical unit or the recording medium Med moves relatively.
1.1) To 2) Y direction, Y direction feed pitch (small) (0.311 mm) Move X direction move process 2.2) to 3) Y direction, Y direction feed pitch (small) (0.311mm) Movement X direction movement process implementation 3.3) to 4) Y direction, Y direction feed pitch (small) (0.311mm) Movement X direction movement process implementation 4.4) to 5) Move to Y direction, Y direction feed pitch (small) (0.311 mm) move X direction move step 5.5) to 6) Move to Y direction, Y direction feed pitch (small) (0.311 mm) move X Execute directional movement process 6.6) to 7) In Y direction, Y direction feed pitch (small) (0.311mm) Execute X direction movement process By repeating these, there is no gap in both X direction and Y direction X, Y that can be exposed and only divided element hologram [group] and X, Y direction feed number (small) The exposure for the area occupied by the direction feed pitch (small) is completed.

  Next, as the movement in the Y direction between the bands, the position of the coordinates (1, 1) of the divided element hologram [group] is changed from 7) to 8) in the Y direction, and the Y direction feed pitch (feed of the divided element hologram [group] itself is sent. (15.542 mm = 17.408 mm-6 times x 0.311 mm) by carrying out the movement and repeating these, one side of the recording medium Med is placed in the X direction. It is possible to perform exposure without a gap in the Y direction.

  In the case of the above-described embodiment of the hologram creation method, there is a possibility that banding (band-like unevenness) is formed in both the X direction and the Y direction. Therefore, other embodiments described below can be applied.

FIG. 10 is a conceptual diagram of a configuration in which the basic array of divided element holograms [group] is tilted, FIG. 11 is a schematic diagram showing an exposure situation in which the basic array shown in FIG. 7 is tilted, and FIG. It is a schematic diagram showing the situation of exposure which moved the scattered object light of the arrangement in the X direction.
In multi-dot exposure, as shown in FIG. 10, exposure can be performed by tilting the spot array in the main scanning direction (Y direction in the figure). In this case, as shown in FIG. 11, there are 16 division element holograms in the Y direction of 2.176 mm, and the exposure pitch in the Y direction is 0.136 mm.

  When the Y-direction element hologram size is smaller than 0.136 mm, interlace recording is performed. When the Y-direction element hologram size is slightly larger than 0.136 mm, the Y-direction element hologram size may be used as it is, or the tilt angle may be increased, and the number of element holograms in the X direction may be less than 16.

  Even when such a basic array tilt exposure method is performed, banding (band-like unevenness) may be formed in both the X direction and the Y direction, as shown in FIG. However, it is possible to reduce banding in the Y direction by employing interlaced recording in the Y direction. Each element hologram has parallax at least in the horizontal direction, and the basic array of the element holograms is tilted in order to expose images with directionality in the X direction and Y direction displayed by the spatial light modulator SLM10. In this case, if the parallax direction is slightly inclined and the image displayed on the spatial light modulation element is not finely adjusted correspondingly, the image is distorted by the inclination direction when viewed as a hologram.

Therefore, still another embodiment relating to the hologram production method of the present invention will be described below.
FIG. 13 is a schematic diagram of a basic array in which the number of X-direction element holograms is reduced to 15.
First, in the present embodiment, the basic arrangement of element holograms is not inclined but has the following configuration.
Basic form-basic arrangement X, Y = 15 columns, 7 rows = 105 In other words, the X direction and the Y direction of the element hologram are set as follows in both the X direction and the Y direction.
[Number of feeds between element holograms] × n + 1 (n is an integer of 1 or more)
Specifically, 1.7 × 1 + 1 = 8
2. 7 × 2 + 1 = 15
3. 7 × 3 + 1 = 22
・
・
・

In the present embodiment, since the element hologram is X, Y = 16, 8, it is preferable to use X, Y = 15, 7 without using one column in the X and Y directions. Become. Of course, X, Y = 8,8 may be used, but sufficient effects are not exhibited.
As the number of element holograms is reduced from 16 to 15, the number of pixels (256 × 256 pixels) used in one element hologram may be increased (in this case, the exposure pitch changes, so caution is required). The number of pixels may not be increased and may be used at the boundary between element holograms accordingly. In that case, since 256 pixels are allocated between 15 element holograms in the X direction, 17 pixels can be allocated per boundary portion, and the degree of freedom in designing the partition wall PA and the tolerance to assembly errors are widened. There are advantages such as.

In the following description, a description will be given in a state where no such device is used.
Element hologram X-direction size: 0.3 mm
Dividing element hologram X-direction pitch: 2.176 mm
Dividing element hologram Y-direction pitch: 2.176 mm
Dividing element hologram [group] Pitch in X direction: 32.640 (= 2.176 × 15)
Dividing element hologram [group] Y-direction pitch: 15.232 (= 2.176 × 7)

Basic form-X-direction movement: Approximately element hologram size Number of feeds between X-direction element holograms: 7 times ≈ 2.176 / 0.3 (integer)
X-direction minimum feed resolution: 0.311 mm≈2.176 mm / 7 times Since there is a slight gap, actually, the element hologram X-direction size is set to 0.32 mm to fill the gap.

FIG. 14 is a schematic diagram showing a simulation for finding the most efficient movement amount in the X direction with respect to the scattered object light of the basic array shown in FIG.
Examination of setting of high efficiency movement in X direction:
(Assumption)
In order to facilitate understanding, only the 15 divided element holograms in the first row of the basic array will be described.
In the horizontal direction, the minimum position number in the X direction is indicated.
-The leftmost scattered object light is the first.
The second scattered object light is positioned at 0.311 mm, which is the minimum X-direction transmission resolution.
Dividing element hologram [group] Within the X-direction pitch 32.640, there are 105 (= 32.640 mm / 0.311 mm) X-direction minimum feed resolution positions.
The second order of the divided element hologram [group] X-direction pitch is located at the 106th position.
As a relative movement, the element hologram [group] moves to the right in the X direction.
An example is shown in which this movement pitch is changed from (a) 1 to (p) 17 times the minimum feed resolution in the X direction as the only movement pitch for recording the entire image.
Since it is difficult to understand the situation when the divided element holograms arranged in the X direction are moved in the X direction as they are, the movement is not shown in the figure in the vertical direction (in fact, it is not shifted in the vertical direction. (It is not expressed as the Y direction).

(A) When the feed amount is 1 time,
It can be seen that exposure can be performed without gaps in the X direction. It can be seen that at least the divided element hologram (2, 1) of the 0th time and the divided element hologram (1, 1) of the 7th movement overlap in the X direction. Therefore, multiple exposure is performed, resulting in image unevenness.

(B) When the feed amount in the X direction is double
From the X direction minimum position number 7 onward, it can be seen that exposure can be performed without a gap. It can be seen that at least the divided element hologram (3, 1) of the zeroth time and the divided element hologram (1, 1) of the seventh movement overlap in the X direction. Therefore, multiple exposure is performed, resulting in image unevenness.

(C) When the feed amount in the X direction is 3 times
From the X direction minimum position number 13 onward, it can be seen that exposure can be performed without a gap. It can be seen that at least the divided element hologram (4, 1) of the zeroth time and the divided element hologram (1, 1) of the seventh movement overlap in the X direction. Therefore, multiple exposure is performed, resulting in image unevenness.

(D) to (f) When the feed amount in the X direction is 4 to 6 times, (h) to (m) 8 to 13 times,
Similar to the above (a), (b), and (c), there are portions that are subjected to multiple exposure, resulting in image unevenness.

(G) When X direction feed amount is 7 times, (n) X direction feed amount is 14 times,
In every movement, the presence / absence of the split element hologram is periodically in the X direction.

(P) When the X-direction feed amount is 16 times or more,
A gap is formed after the second lowest X-direction position number 106 in the second order. Such an X-direction scan can be avoided by performing the scan twice or more, but the sequence is more complicated and the scan time increases, which is contrary to the main purpose of high productivity.

(O) When the feed amount in the X direction is 15 times
It can be seen that exposure can be performed without a gap after the minimum position number 85 in the X direction, and it is understood that 15 times the minimum feed resolution in the X direction is the most appropriate, with the movement pitch for recording the entire image being a constant pitch. This numerical value coincides with the number of divided element holograms in the X direction. It should be noted that uniform exposure can be performed without forming a jagged image in the horizontal direction by performing a procedure so that data is not transmitted before the X-direction minimum position number 84.

FIG. 15 is a schematic diagram showing an exposure situation in which the scattered object light of the basic arrangement shown in FIG. 13 is moved 10 times in the X direction with a resolution of 15 times.
As can be seen from FIG. 15, the basic array shows 10 movements in the X direction (15 times the minimum feed resolution in the X direction). With respect to the X direction, it can be seen that recording has been performed without gaps and without duplication since the sixth movement. After the exposure of the desired exposure width is completed, the coordinates (1, 1) return to the position of the original coordinates (1, 1) only in the X direction.

Next, since there is a gap in the Y direction, the next exposure is repeated.
FIG. 16 is a schematic diagram showing an exposure situation in which the scattered object light having the basic arrangement shown in FIG. 13 is moved in the Y direction.
Examination of setting of high-efficiency movement in Y direction:
(Assumption)
In order to facilitate understanding, only the divided element hologram in the first column of the basic array and the feed amount of 8 times will be described.
In the vertical direction, the minimum position number in the Y direction is indicated.
・ The top spotted object beam is the first.
The second scattered object light is located at 0.311 mm which is the minimum Y-direction transmission resolution.
There are 56 (= 17.408 mm / 0.311 mm) Y-direction minimum feed resolution positions in the Y-direction pitch 17.408 of the divided element hologram [group].
The second order of the pitch in the Y direction of the divided element hologram [group] is located at the 57th position.
As a relative movement, the element hologram [group] moves downward in the Y direction.
-This movement pitch is the only movement pitch for recording the entire image, and shows when the feed amount is 8 times.
Since it is difficult to understand when the divided element holograms arranged in the Y direction are moved in the Y direction as they are, it is difficult to understand the movement in the figure in the horizontal direction (in fact, it is not shifted in the horizontal direction. (It is not expressed in the X direction).

  As can be seen from FIG. 16, when the moving feed amount is 8 times, exposure can be performed without a gap after the minimum position number 43 in the Y direction. The numerical value of 8 times the Y-direction minimum feed resolution matches the number of divided element holograms in the Y direction. By performing a procedure so that data is not transmitted before the Y-direction minimum position number 42, uniform exposure can be performed without causing the lateral direction to be jagged.

FIG. 17 is a schematic diagram showing a part of the exposure situation in which the scattered object light of the basic arrangement shown in FIG. 13 is moved 10 times in the X direction and 8 times in the Y direction.
A state after the following three steps (1), (2), and (3) are sequentially repeated 10 times is shown.
(1) A process in which the basic array is moved 10 times and exposed with an X-direction movement amount 15 times the X-direction minimum feed resolution.
(2) A step in which the basic arrangement returns the movement distance for 10 times at once with the X-direction movement amount being 15 times the X-direction minimum feed resolution.
(3) A step in which the basic array moves once with the Y-direction movement amount being 8 times the Y-direction minimum feed resolution.

  By repeating these exposures / movements, the exposure operation can be filled at a constant speed without gaps. During exposure of the second half of each scan, it is possible to prevent (straighten) exposure at a desired position by measures such as not transmitting an image signal.

  According to the above hologram creation method, when the number of display areas of the object light is X and Y, the X direction and the Y direction of the element hologram in both the X direction and the Y direction are the inter-element hologram feed number × n + 1. Become. Specifically, 7 × 1 + 1 = 8, 7 × 2 + 1 = 15, 7 × 3 + 1 = 22. When the element hologram is, for example, X, Y = 16,8, X, Y = 15, 8 without using one column in the X direction. As the number of element holograms decreases from 16 to 15, the number of pixels used in one element hologram can be increased. Further, the number of pixels is not increased, and it may be used at the boundary between element holograms accordingly. In that case, since a predetermined pixel can be allocated among 15 element holograms in the X direction, there are advantages such as freedom in designing the partition member and wider tolerance for assembly errors.

(Example)
Exposure time example 1
i.A4 size 210 × 297mm
ii. Element hologram size 0.3mm
iii. Exposure time / time 0.25 seconds
iv. 120 dots
v. Exposure time calculation (210 × 297 mm) ÷ (0.3 × 0.3 mm) × 0.25 seconds / 120 dots = 1443.75 seconds As described above, the exposure time is as short as about 24 minutes and the vibration waiting time is also long. Shortened. In addition, an element hologram size of 0.3 mm can achieve high image quality.

Exposure time example 2
i. By using a pulse laser, the vibration waiting time can be shortened to near zero, and the stage can be moved continuously without stopping, so the SLM frequency limit is 120 Hz, and the stage speed and exposure time become rapid. .
ii. Vibration waiting time 0 seconds
iii. Stage moving speed = 60 mm / sec
iv. Exposure area / head 32.640 × 17.408mm
v. Exposure time calculation X-direction movement time Movement distance = 210 mm + 32.64
2. = 242.64mm
X direction travel time = 242.64 / 60 mm / s
2. = 4.044s
Acceleration / deceleration time during exposure 1s both
Return time (same speed)
1.2s
Acceleration time and deceleration time when returning Both 0.5s
= 4.044 + 1 + 1 + 2 + 0.5 + 0.5
≒ 9
Number of movements in the Y direction Movement distance in the Y direction 1.297 + 17.408 × 2mm
2. = 331.816 mm
Y direction moving pitch 1.0.311 mm (minimum resolution) × 8 pitches = 2.488 mm
Acceleration / deceleration time for Y-direction movement Both 0.3s
= (9 + 0.3 + 0.3s) × (331.816 / 2.488)
= 1280 seconds About 21 minutes.

Example of interlace recording in both the X and Y directions without tilting the basic array
i. Rotate basic array 90 degrees
ii. X, Y = 8 columns, 15 rows = 120
iii. In this way, 8 to 15 lines can be exposed at one time by scanning once in the X direction, so that exposure was possible earlier.

Example of interlace recording in both the X and Y directions without tilting the basic array
i. Naturally, exposure is possible even faster by exposing not only one-way but also the X-direction return path.

  The manufacturing center position accuracy of the lens array L12 can be dealt with by changing the display pixel position. It is necessary to measure the center position of the lens array L12 in advance. As another example, four or more types of lasers can be used to improve color reproducibility. In addition, the quality of the reproduced image can be improved by color matching.

It is a block diagram of the hologram production apparatus which concerns on embodiment of this invention. FIG. 3 is an enlarged configuration diagram showing a configuration between a spatial light modulation element and a recording medium. It is a block diagram in the case of using multi-reference light. It is a principal part enlarged view of FIG. It is a block diagram which shows the example of the optical system for hologram creation using reflection type SLM. FIG. 6 is a modification of FIG. 5 and is a configuration diagram using a reduction optical system. It is the schematic diagram showing the basic arrangement of the division element hologram fundamentally determined by a spatial light modulation element and a lens array. FIG. 8 is a schematic diagram illustrating a situation where the scattered object light of the basic array illustrated in FIG. 7 is moved in the X direction and exposed without a gap. It is the schematic diagram which expand | deployed the exposure shown in FIG. 8 to the Y direction. FIG. 10 is a conceptual diagram of a configuration in which the basic array of divided element holograms [group] is tilted. It is a schematic diagram showing the condition of the exposure which inclined the basic arrangement | sequence shown in FIG. It is a schematic diagram showing the condition of the exposure which moved the scattered scattered object light of the basic arrangement in the X direction. It is a schematic diagram of the basic arrangement in which the number of X-direction element holograms is reduced to 15. It is a schematic diagram which shows the simulation for finding the most efficient movement amount to the X direction with respect to the scattered object light of the basic arrangement | sequence shown in FIG. It is a schematic diagram showing the situation of exposure which moved the scattered object light of the basic arrangement shown in FIG. 13 ten times with a resolution of 15 times in the X direction. It is a schematic diagram showing the condition of the exposure which moved the scattered object light of the basic arrangement shown in FIG. 13 in the Y direction. FIG. 14 is a schematic diagram showing a part of an exposure situation in which the scattered object light of the basic arrangement shown in FIG. 13 is moved 10 times in the X direction and 8 times in the Y direction. It is a block diagram of the conventional hologram production apparatus which expands and projects the decomposition | disassembly image of SLM on a diffusion plate. It is a block diagram of the hologram production apparatus which records 12 element holograms at once by an afocal reduction optical system. It is a block diagram of the hologram production apparatus which installed the partition plate between the liquid crystal panel and the lens array.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Hologram production apparatus 110 ... Interlace exposure means BE ... Beam expander (beam diameter expansion means)
D10 ... Diffusion plate (diffusion screen)
L10: First lens L11: Second lens L12: Lens array L22, L23: Reference light lens array (collimator lens)
LS ... Laser light source MS ... Mask, reference light mask Med ... Hologram recording medium Ob ... Object light PA ... Partition wall (partition member)
Rb: Reference light SLM10: Transmission type spatial light modulation element SLM11: Reflection type spatial light modulation element

Claims (9)

A hologram creating method for performing interference recording by dividing a laser light source into object light and reference light,
The object light is enlarged by a beam diameter enlarging means, and hologram recording information is given to the object light whose beam diameter is enlarged by a spatial light modulation element that divides and displays a hologram recording image in a plurality of image display areas,
The object light given the information for hologram recording is diffused for each of the divided image areas by a diffusion screen and a partition member,
Irradiating diffused light for each of the divided image areas as object light having a constant interval on the hologram recording medium by a lens array composed of a plurality of lenses corresponding to each divided area,
Irradiating the reference light from the back of the hologram recording medium to record interference with the object light having a certain interval;
A hologram creation method for performing interlaced exposure in which a predetermined interval of object light on the hologram recording medium is divided into a plurality of pitches, and a relative position with respect to the hologram recording medium is moved according to the pitches to repeatedly record an interference state.   The hologram production method according to claim 1, wherein a mask disposed on the hologram recording medium blocks light other than object light at a focal position of the lens array.   The hologram creating method according to claim 1, wherein the reference light is irradiated only to the irradiation position of the object light having a constant interval by a lens array and a collimator lens.   The hologram production method according to claim 2, wherein irradiation is limited only to a position where the object light limited by the object light mask is irradiated by the reference light mask arranged on the reference light side. (X, Y) = (aXn + 1, bXn + 1) (n is an integer equal to or greater than 1).
Number of display areas of object light: (X, Y)
Division pitch of object light at regular intervals: a (X direction), b (Y direction)
The method for producing a hologram according to any one of claims 1 to 4. A hologram creating apparatus that divides a laser light source into an object beam and a reference beam and performs interference recording on a hologram recording medium,
Beam diameter expanding means for expanding the beam diameter of the object light;
A spatial light modulation element that divides and displays a hologram recording image in a plurality of image display areas and gives hologram recording information to the object light;
A diffusion and partition member that converts the object light from the spatial light modulator into diffused light for each of the divided image regions;
A lens array comprising a plurality of lenses corresponding to each divided castle and irradiating diffused light for each divided image region as object light having a fixed interval on a hologram recording medium,
A reference light optical system that irradiates the reference light from the back surface of the hologram recording medium and interferes with the object light having a constant interval;
A hologram production apparatus comprising: an interlace exposure unit that divides a predetermined interval of object light on the hologram recording medium into a plurality of pitches and performs a moving exposure process on a relative position with respect to the hologram recording medium according to the pitches.   The hologram creating apparatus according to claim 6, further comprising a mask disposed on the hologram recording medium and having an aperture for object light at a focal position of the lens array.   The hologram creating apparatus according to claim 6 or 7, wherein the reference light optical system includes a lens array and a collimator lens that irradiates only the irradiation position of the object light having a predetermined interval.   The hologram according to claim 7 or 8, wherein the reference light optical system includes a reference light mask having an opening for irradiating the reference light at a position irradiated with the object light limited by the mask for object light. Creation device.