JP6888233B2 - Color hologram recording device and color hologram manufacturing method - Google Patents

Description

The present invention relates to a color hologram recording device for recording a color hologram and a method for manufacturing a color hologram.

Conventionally, there is a holography technique as a recording / reproducing method of three-dimensional subject information. This holography technique causes light reflected from an object (object light) to interfere with light different from the object light (reference light), and records the fringes (interference fringes) formed by the interference on a photosensitive medium. .. The photosensitive medium on which these interference fringes are recorded is called a hologram. That is, the hologram is a three-dimensional subject information recorded on a two-dimensional plane.

In recent years, a wave surface printer that records interference fringes for each minute cell called an element hologram on a hologram recording medium has been known (Patent Document 1).
This wave surface printer reproduces three-dimensional digital data (hologram data) generated in a computer using a spatial light modulator (SLM), and is different from the obtained complex amplitude distribution (object light). Interference fringes between the object light guided to the hologram surface by the path and the interfering light (reference light) are recorded on the hologram recording medium.
This wave surface printer records holograms in cell units while moving element holograms (cells) up, down, left, and right, and finally generates one large hologram.

In holography called "volume type", a single hologram recording medium is exposed (overwritten) three times according to each primary color with a light source having wavelengths corresponding to the three primary colors to achieve colorization. It can be realized (Non-Patent Document 1).

Japanese Unexamined Patent Publication No. 2016-212231

Toshihiro Kubota, "Introduction to Holography-Principles and Practice", published by Asakura Shoten, p. 191, November 20, 1995

In order to generate a volumetric color hologram with a conventional wave surface printer, it is necessary to perform three exposures (overwriting) for each primary color, so that the diffraction efficiency at the time of image reproduction per color is lowered. There is a problem.
This is because when color recording is performed on a hologram recording medium, it is necessary to superimpose a monochrome pattern of interference fringes having fineness corresponding to each color on the same photosensitive layer, and the intensity of light and shade per color (light intensity). ) Will be distributed. This problem of multiple recording is also described in "P. Hariharan," Basics of Holography ", p.35, Cambridge University Press, 2002/03/14".

Therefore, it is an object of the present invention to provide a color hologram recording device and a color hologram manufacturing method capable of generating a color hologram in which a decrease in diffraction efficiency is suppressed during hologram reproduction (image reproduction).

In order to solve the above problems, the color hologram recording device according to the present invention is a color hologram recording device that records interference fringes of RGB colors, which are the three primary colors, on a hologram recording medium in cell units, and includes a light source switching means and a light source switching means. An optical path separation means, a spatial modulation means, a recording medium moving means, and a control means are provided, and the control means targets all cells as a writing target at the time of recording the interference fringes for G color, and the interference fringes for R color. At the time of recording, cells that are spaced one cell at a time are targeted for writing, and at the time of recording interference fringes for B color, cells that are not subject to writing at the time of recording interference fringes for R color are targeted for writing.

In such a configuration, the color hologram recording device switches one of the laser light sources of each color of RGB to emit light by the light source switching means. Further, the color hologram recording device separates the light emitted by switching by the light source switching means into two optical paths by the optical path separating means. Further, the color hologram recording device modulates one of the separated lights as object light by the hologram data by the spatial modulation means. Further, the color hologram recording device uses the recording medium moving means to move the cell to be written on the hologram recording medium to an irradiation position where the object light and the reference light, which is the other light separated by the optical path separating means, overlap.

Then, the color hologram recording device drives the recording medium moving means in cell units for each RGB color by the control means, displays the hologram data corresponding to the cell to be written on the spatial modulation means, and displays the corresponding color. The laser beam of the above is controlled to be emitted by the light source switching means.
At this time, the control means targets all cells for writing when recording the interference fringes for the G color. Further, the control means sets the cells to be written at intervals of one cell at the time of recording the interference fringes for R color. Further, the control means targets a cell that is not a write target at the time of recording the interference fringes for the R color at the time of recording the interference fringes for the B color.

In this way, the cells for R color and the cells for B color have a complementary relationship with each other, and the interference fringes corresponding to R color and B color are applied to the hologram recording medium by one exposure at the same place. Will be recorded.
Since all the cells for G color are to be written, the color hologram recording device can generate RGB color holograms by two exposures as a whole.

The R color cell and the B color cell are preferably offset from the G color cell by a predetermined offset so that the cell boundaries do not overlap. This makes it possible to make the cell boundaries inconspicuous during hologram reproduction.

Further, in order to solve the above problems, the color hologram manufacturing method according to the present invention is a spatial modulation means that modulates one light that separates laser light into two optical paths as object light, and the other light that is separated. A color hologram recording device provided with a recording medium moving means for moving a cell to be written on the hologram recording medium to an irradiation position where the light and the object light overlap, and interfering fringes of RGB colors, which are the three primary colors, are formed. It is a color hologram manufacturing method for recording on a hologram recording medium, and is a procedure including a G light recording step and an RB light recording step.

In this procedure, in the hologram manufacturing method, as a G optical recording step, cells for G color are assigned to the hologram surface of the hologram recording medium without intervals, and hologram data for G color corresponding to the cells for G color is used. Is displayed on the space modulation means to emit a G-color laser beam.
Further, as an RB optical recording step, cells for R color and cells for B color are complementaryly and alternately assigned to the hologram surface of the hologram recording medium, and the corresponding R color is assigned to the cells for R color. Hologram data for B color is displayed on the spatial modulation means to emit R color laser light, and for cells for B color, the corresponding hologram data for B color is displayed on the spatial modulation means for B color. Makes the laser beam emit light.
Thereby, the hologram manufacturing method can record an RGB color hologram by exposing the hologram surface twice.

The present invention has the following excellent effects.
According to the present invention, when a color hologram of three primary colors is generated, the hologram can be generated by writing (exposure) twice. As a result, the present invention can widen the dynamic range (amplitude) of each color in one writing as compared with the conventional three writings for each of the three primary colors, and suppresses a decrease in diffraction efficiency during hologram reproduction. Can be done.

It is an overall block diagram which shows the structure of the color hologram recording apparatus which concerns on embodiment of this invention. It is a functional block diagram which shows the structure of the hologram recording control device of FIG. It is a structural diagram of a cell to be written, in which (a) is a structural diagram of a cell for green, (b) is a structural diagram of a cell for red, and (c) is a structural diagram of a cell for blue. It is a flowchart which shows the operation of the color hologram recording apparatus which concerns on embodiment of this invention. It is a structural diagram of a cell of another example to be written, (a) is a structural diagram of a cell for green, (b) is a structural diagram of a cell for red, and (c) is a structural diagram of a cell for blue. Is. It is an overall block diagram which shows the structure of the color hologram recording apparatus which concerns on embodiment of a reference example.

Hereinafter, a mode for carrying out the color hologram recording apparatus according to the present invention will be described in detail with reference to the drawings.

[Configuration of color hologram recording device]
The configuration of the color hologram recording device 1 according to the embodiment of the present invention will be described with reference to FIG.

The color hologram recording device 1 records a color hologram on the hologram recording medium H in units of cells EH, which are rectangular regions having a predetermined size. Here, the color hologram recording apparatus 1 includes a light source 10, a light source switching means 11, a 1/2-wavelength plate 12, the optical path separating means 13, a spatial filter 14, a mirror 15 ₍₁₅ 1, 15 _2), The light path changing means 16, the spatial light modulation means 17, the unnecessary light removing means 18, the reduction optical system 19, the recording medium moving means 20, and the hologram recording control device 50 are provided.

The light source 10 emits coherent light (laser light). _{The light source 10 is a light source 10 R} , 10 _G , 10 _B corresponding to the colors (R, G, B) of the three primary colors.
The light source 10 _R emits a red laser beam. The light source 10 _R emits laser light having a wavelength of, for example, 635 nm among the wavelengths of red light of 620 to 750 nm.
The light source 10 _G emits a green laser beam. The light source 10 _G emits laser light having a wavelength of, for example, 532 nm among the wavelengths of green light of 495 to 570 nm.
The light source 10 _B emits a blue laser beam. The light source 10 _B emits laser light having a wavelength of, for example, 460 nm among the wavelengths of blue light of 450 to 495 nm.
The light source 10 (10 _R , 10 _G , 10 _B ) is arranged in advance so that the optical axes coincide with each other on the output from the light source switching means 11 described later.
The light source 10 (10 _R , 10 _G , 10 _B ) emits each laser beam to the light source switching means 11.

The light source switching means 11 switches _{the laser beams of the light sources 10 (10 R} , 10 _G , 10 _B ) and emits them on the same optical path.
Here, the light source switching means 11 includes a shutter 110, a diameter expanding means 111, mirrors 112, 113, and an optical path changing means 114.

The shutter 110 passes and blocks the laser beam from the light source 10. The shutter 110 corresponds to the light sources 10 _R , 10 _G , and 10 _{B, and includes shutters 110 R} , 110 _G , and 110 _B that control the emission of the respective laser beams. As these shutters 110, an electromagnetic shutter, or preferably an optical shutter such as an acousto-optic modulator or an acoustic-optical polarizing device can be used.
The shutters 110 _R , 110 _G , and 110 _B are controlled to pass or block the laser beam according to an instruction from the hologram recording control device 50 described later.

The diameter expanding means 111 makes the beam diameter of the laser light that has passed through the shutter 110 a collimated beam whose diameter is enlarged. The diameter expanding means 111 can be composed of, for example, two convex lenses. Among the diameter expanding means 111, the convex lens on the shutter 110 side expands the beam diameter of the laser light, and the other convex lens converts the laser light having the expanded beam diameter into parallel light.

The mirror 112 reflects the red laser beam emitted by the _{light source 10 R to the optical path changing means 114.}
The mirror 113 reflects the blue laser light emitted by the _{light source 10 B to the optical path changing means 114.}

The optical path changing means 114 _{transmits the green laser light emitted by the light source 10 G} , reflects the red laser light reflected by the mirror 112, and reflects the blue laser light reflected by the mirror 113 to emit each laser light. The optical path is changed to the 1/2 wavelength plate 12. The optical path changing means 114 can be configured by, for example, a cross-half mirror.
The light source switching means 11 is not limited to this configuration as long as it has a configuration in which the optical axes of the laser beams are aligned.
In this way, the light source switching means 11 switches and emits any one of the red laser light, the blue laser light, and the green laser light.

The 1/2 wave plate 12 rotates the plane of polarization of the laser beam incident from the optical path changing means 114. Here, the 1/2 wave plate 12 rotates the plane of polarization to 45 degree polarized light. The light whose plane of polarization is rotated by 45 degrees is emitted to the optical path separating means 13.

The optical path separating means 13 separates the incident laser light according to the polarization component. The optical path separating means 13 can be composed of a polarizing beam splitter (PBS). The optical path separating means 13, of the light incident from 1/2-wavelength plate 12, for P-polarized light, as the light for generating the object beam transmitted through the mirror 15 _2, for the S-polarized light, the reference light As the light that becomes, it is reflected by the space filter 14.

The spatial filter 14 shields the light on the outer peripheral portion of the light separated by the optical path separating means 13 other than irradiating the cell EH as reference light. The light passing through the spatial filter 14 is emitted to the mirror 15 _1.

The mirror 15 is a total mirror that totally reflects the incident light. Here, the mirror 15 ₁ reflects light passing through the spatial filter 14 in a cell EH to be written in the holographic recording medium H. The mirror 15 ₂ are separated by the optical path separating means 13, for reflecting the transmitted light on the optical path changing means 16.

The optical path changing means 16 separates incident light according to its polarization component. The optical path changing means 16 can be composed of a polarizing beam splitter (PBS). The optical path changing means 16 transmits P-polarized light reflected by the mirror 15 ₂ to the spatial light modulating means 17. Further, the optical path changing means 16 reflects the modulated light (S-polarized light) reflected by the spatial light modulation means 17 and emits the light (S-polarized light) to the unnecessary light removing means 18.

The spatial light modulation means 17 modulates the light intensity distribution or phase distribution of the hologram data. The spatial light modulation means 17 can be configured by an SLM (Spatial Light Modulator).
The spatial light modulation means 17 displays hologram data for each color input from the hologram recording control device 50 as page data, and displays light (complex amplitude distribution) modulated by the light emitted from the optical path changing means 16 as object light. Emit as.

The unnecessary light removing means 18 removes unnecessary light emitted from the spatial light modulation means 17 together with the object light. The unnecessary light removing means 18 allows only the primary diffracted light, which is the object light, to pass through the diffracted light of the spatial light modulation means 17. That is, the unnecessary light removing means 18 removes the 0th-order diffracted light and the higher-order diffracted light. The unnecessary light removing means 18 emits object light, which is primary diffracted light, to the reduction optical system 19.

The unnecessary light removing means 18 can be composed of a lens 180, a shielding plate 181 and a lens 182.
The lens 180 is a convex lens that collects the light incident from the optical path changing means 16 on the shielding plate 181.
The shielding plate 181 removes unnecessary light, and is a mask that shields half of the object light for half-zone plate processing.
The lens 182 is a convex lens that converts light that has passed through the shielding plate 181 into parallel light.

The reduction optical system 19 reduces the light incident from the unnecessary light removing means 18. That is, the reduction optical system 19 reduces and irradiates the light of the pixel size of the SLM, which is the spatial light modulation means 17, into the cell EH. The reduction optical system 19 can be composed of two convex lenses 190 and 191 having different focal lengths. As a result, the viewing angle at the time of hologram reproduction can be widened by the diffraction of light.

The recording medium moving means 20 moves the hologram recording medium H, which is the object for recording hologram data, in the horizontal direction and the vertical direction for each cell EH of the writing unit of the hologram data. The recording medium moving means 20 can be configured by, for example, an XY stage.
The recording medium moving means 20 is controlled by the hologram recording control device 50 described later so that the cell EH of the writing unit is at an irradiation position where the object light and the reference light overlap.
It is desirable that the size of the cell EH is equal to or less than one minute (1/60 degree) in terms of visual perception of one pixel, which is the resolution of the human eye. For example, assuming that the viewing distance is about 2 m, the size of the cell EH is about 0.5 to 1.0 mm.

The hologram recording control device (control means) 50 controls the operation of the entire color hologram recording device 1. The hologram recording control device 50 controls the recording medium moving means 20 so that the cell EH to be written is at an irradiation position (reference position) where the reference light and the object light overlap.

Here, the configuration of the hologram recording control device 50 will be described with reference to FIG. 2 (see FIG. 1 as appropriate).
As shown in FIG. 2, the hologram recording control device 50 includes a light source control means 51, a cell position control means 52, a storage means 53, a cell data display means 54, and a synchronization means 55.

The light source control means 51 controls ON / OFF of the irradiation of the light source 10. The light source control means 51 turns on the irradiation of one of the shutters 110 and irradiates the other shutters with respect to _{the shutters 110 R} , 110 _G , 110 _B of the light source switching means 11 according to the instruction from the synchronization means 55. Turn off.
As a result, the hologram recording control device 50 can irradiate only the laser beam of any of the three primary colors only when the interference fringes are recorded in the cell EH to be written on the hologram recording medium H.

The cell position control means 52 drives and controls the recording medium moving means 20 so that the cell EH to be written is moved to a reference position where the object light and the reference light overlap.
The cell position control means 52 drives and controls the recording medium moving means 20 so as to move the cell EH designated by the synchronization means 55 to the reference position, and after the drive is completed, the drive completion is sent to the synchronization means 55. Notice.

Here, with reference to FIG. 3, cells to be written in each color in the hologram recording medium H will be described. Here, in consideration of the legibility of the drawing, the number of cells in the hologram recording medium H is set to 5 in both vertical and horizontal directions.

As shown in FIG. 3 (a), for the green hologram data corresponding to the (G) (G light data) is assigned as the target writing all cells EH of the hologram plane (cell EH G for G _color).
Further, as shown in FIG. 3B, for the hologram data (R optical data) corresponding to the red color (R), the cell EH to be written (cell EH for R color) is opened horizontally and vertically one cell at a time. _R ) is assigned. The position of the cell EH _R is the cell EH _G, and position shifted half cell content horizontally and vertically, respectively. In FIG. 3 (b), shows the cell boundaries EH _G by a broken line.

Further, as shown in FIG. 3C, for the hologram data (B optical data) corresponding to blue (B), one cell is opened horizontally and vertically, and the cell EH to be written (cell EH for B color) is written. _B ) is assigned. Further, the position of the _{cell EH B is set to be} a position shifted horizontally and vertically by 1/2 cell with respect to _{the cell EHG G} , and is a position to complement _{the cell EHR of the R optical data.} In FIG. 3 (c), it represents the boundary of the cell EH _G by a broken line.
Here, the cell EH _R and cell EH _G, the cell EH _G, but shifted by 1/2 cell, it is not always strictly necessary to shift by 1/2 cell, at least the cell EH _R and cell EH _G cell boundaries may if overlap with cell EH _G.

Returning to FIG. 1, the configuration of the color hologram recording device 1 will be described.
As described with reference to FIG. 3, the cell position control means 52 moves a cell different for each color to a reference position illuminated by the reference light and the object light under the control of the synchronization means 55.

The storage means 53 stores the hologram data generated in advance. The hologram data is color hologram data generated by a general computer-generated hologram (CGH) or the like. Here, in the storage means 53, the G optical data obtained by extracting only the green (G) component, the R optical data obtained by extracting only the red (R) component, and the blue (B) component of the hologram data are stored. The B optical data obtained by extracting only the data is stored.
The storage means 53 can be configured by a general storage device such as a hard disk or a semiconductor memory. Here, it is decided that the G optical data, the R optical data, and the B optical data are separately stored in the storage means 53 in advance, but the color hologram data is stored and the cell data display means described later is stored. 54 may extract hologram data of a required color.

The cell data display means 54 outputs hologram data to be displayed on the spatial light modulation means (SLM) 17. The cell data display means 54 reads out the cell EH to be written and the hologram data corresponding to the color to be written from the storage means 53 according to the instruction from the synchronization means 55, and causes the spatial light modulation means (SLM) 17 to read the hologram data. Output.
As a result, the hologram recording control device 50 can use the hologram data for each color of RGB corresponding to the cell EH to be written as object light.

The synchronization means 55 synchronously controls the operation of the entire color hologram recording device 1. The synchronization means 55 instructs the cell position control means 52 to move the cell EH to be written by being instructed to start from the outside. For example, when displaying green hologram data, the synchronization means 55 sets the upper left cell of the hologram recording medium H as the first writing target, and sequentially switches the writing target in the horizontal direction and the vertical direction. Also, to display red or blue hologram data, synchronization means 55, as described in FIG. 3 (b), (c) , the cell EH _G targeting green, shifting 1/2 cells Te, switched cells EH R position to complement the red or blue one another in one cell _every the EH _B to sequentially write target.

Further, the synchronization means 55 instructs the cell data display means 54 to display the hologram data on the cell EH to be written in synchronization with the movement of the cell EH. That is, the synchronization means 55 notifies the cell data display means 54 of the color to be written and the position of the cell to be written, so that the cell data display means 54 can perform the corresponding hologram data (G optical data). , R optical data, B optical data) is displayed.

Then, when the drive of the cell EH by the cell position control means 52 and the display of the hologram data by the cell data display means 54 are completed, the synchronization means 55 is written to the light source control means 51 for each color to be written. , The shutter 110 of the light source 10 is opened, and an instruction is given to irradiate the laser beam.

As described above, the hologram recording control device 50 records the interference fringes on the entire surface of the hologram recording medium H for the green hologram data (G optical data) which has a large contribution to the resolution in terms of visual characteristics. Further, the hologram recording control device 50 records interference fringes on the entire surface of the hologram recording medium H in a pattern that complements each of the red and blue hologram data (R optical data and B optical data).

As a result, when the hologram recording control device 50 records the interference fringes on the hologram recording medium H, the interference fringes using the G optical data and the R optical data and the G optical data are generated at any position on the hologram recording medium H. And only one of the interference fringes using the B optical data will be recorded.

By configuring the color hologram recording device 1 as described above, the color hologram recording device 1 generates a color hologram only by writing (exposure) twice to the same position of the hologram recording medium H. be able to.
As a result, the color hologram recording device 1 can have a wider dynamic range per color as compared with the case where writing is performed three times as in the conventional case, and the diffraction efficiency (contribution to the hologram reproduction in the illumination light). It is possible to suppress a decrease in the ratio of light to be emitted.

Generally, when recording interference fringes on the hologram recording medium H, the dynamic range is limited. Therefore, when overwriting is performed on the hologram recording medium H, the dynamic range (amplitude) of one time is reduced to 1 / N with respect to N times of overwriting. In this case, the diffraction efficiency, which is the ratio of the illumination light during hologram reproduction that contributes to image reproduction, is reduced to ^{1 / N 2.}
That is, since the color hologram recording device 1 usually has R and B spatially structured as compared with the conventional method of writing N = 3, it is possible to generate a color hologram by writing N = 2. it can. As a result, the color hologram recording device 1 can improve the diffraction efficiency more than twice as much as the conventional one.

Further, in the color hologram recording device 1, the joints between the cells are dispersed by shifting the cells of the R optical data and the B optical data by 1/2 cell with respect to the cells of the G optical data. The joints between cells can be made inconspicuous.
As a result, the color hologram recording device 1 can improve the visibility of the generated hologram during reproduction.

[Operation of color hologram recording device]
Next, the operation (color hologram manufacturing method) of the color hologram recording device 1 according to the embodiment of the present invention will be described with reference to FIG. 4 (see FIGS. 1 and 2 for the configuration as appropriate). In the following operation, the color hologram recording device 1 performs a G light recording step of recording a hologram of G light and an RB light recording step of recording holograms of R light and B light, but the order is arbitrary. Therefore, it does not matter from the hologram of any color light.

<G optical recording process>
First, in step S1, the color hologram recording device 1 moves the cell EH to which the G optical data is to be written to the reference position (irradiation position). That is, the hologram recording control device 50 instructs the synchronization means 55 to the cell position control means 52 to move the cell EH corresponding to the G optical data to the reference position. Then, the cell position control means 52 drives and controls the recording medium moving means 20, moves the hologram recording medium H in the plane direction, and moves the cell EH to be written to the reference position.
The color hologram recording apparatus 1, each time of operating a step S1, as described with reference to FIG. 3 (a), so as to cover all the hologram surface, sequentially moves the position of the cell EH _G.

Then, in step S2, the color hologram recording device 1 displays the hologram data (G optical data) corresponding to the cell EH to be written on the spatial light modulation means (SLM) 17. That is, the hologram recording control device 50 reads the G optical data corresponding to the cell EH to be written from the storage means 53 by the G optical data display means 540 of the cell data display means 54 according to the instruction from the synchronization means 55. Output to SLM17.

After that, in step S3, the color hologram recording device 1 irradiates the cell EH to be written with the object light and the reference light, and records the interference fringes. That is, the hologram recording control device 50 opens the shutter 110 _{G of the light source 10 G} that emits green laser light by the light source control means 51 according to the instruction from the synchronization means 55, and irradiates the laser light.
As a result, the green laser light separated by the optical path separating means 13 is irradiated to the cell EH to be written as the object light and the reference light, respectively, and the interference fringes are recorded. After the irradiation for a predetermined time for recording the interference fringes is completed, the light source control means 51 _{closes the shutter 110 G} and stops the irradiation of the laser beam.

Then, in step S4, the color hologram recording device 1 determines whether or not the recording of the hologram recording medium H in all the cells EH is completed by the synchronization means 55.
Here, when the recording to all the cells EH is not completed (No), the color hologram recording device 1 returns to step S1 and continues the operation. On the other hand, when the recording to all the cells EH is completed (Yes), the color hologram recording device 1 proceeds to step S5.

<RB optical recording process: R optical recording>
Next, in step S5, the color hologram recording device 1 moves the cell EH to which the R optical data is to be written to the reference position (irradiation position). That is, the hologram recording control device 50 instructs the cell position control means 52 from the synchronization means 55 to move the cell EH corresponding to the R optical data to the reference position. Then, the cell position control means 52 drives and controls the recording medium moving means 20, moves the hologram recording medium H in the plane direction, and moves the cell EH to be written to the reference position.
Each time the color hologram recording device 1 operates in step S5, the color hologram recording device 1 is shifted by 1/2 in the horizontal direction and the vertical direction with respect to the cell corresponding to the G light, as described in FIG. 3 (b). and, opening one cell, sequentially moves the position of the cell EH _R.

Then, in step S6, the color hologram recording device 1 displays the hologram data (R optical data) corresponding to the cell EH to be written on the spatial light modulation means (SLM) 17. That is, the hologram recording control device 50 reads the R optical data corresponding to the cell EH to be written from the storage means 53 by the R optical data display means 541 of the cell data display means 54 according to the instruction from the synchronization means 55. Output to SLM17.

After that, in step S7, the color hologram recording device 1 irradiates the cell EH to be written with the object light and the reference light, and records the interference fringes. That is, the hologram recording control device 50 opens the shutter 110 _{R of the light source 10 R} that emits red laser light by the light source control means 51 according to the instruction from the synchronization means 55, and irradiates the laser light.
As a result, the red laser light separated by the optical path separating means 13 is irradiated to the cell EH to be written as the object light and the reference light, respectively, and the interference fringes are recorded. After the irradiation for a predetermined time for recording the interference fringes is completed, the light source control means 51 _{closes the shutter 110 R} and stops the irradiation of the laser beam.

Then, in step S8, the color hologram recording device 1 determines whether or not the recording of the hologram recording medium H in the cell EH targeting the red color is completed by the synchronization means 55.
Here, when the recording to the cell EH targeting red is not completed (No), the color hologram recording device 1 returns to step S5 and continues the operation. On the other hand, when the recording in the cell EH targeting red is completed (Yes), the color hologram recording device 1 proceeds to step S9.

<RB optical recording process: B optical recording>
Next, in step S9, the color hologram recording device 1 moves the cell EH to which the B optical data is to be written to the reference position (irradiation position). That is, the hologram recording control device 50 instructs the cell position control means 52 from the synchronization means 55 to move the cell EH corresponding to the B optical data to the reference position. Then, the cell position control means 52 drives and controls the recording medium moving means 20, moves the hologram recording medium H in the plane direction, and moves the cell EH to be written to the reference position.
Each time the color hologram recording device 1 operates in step S9, the color hologram recording device 1 is shifted by 1/2 in the horizontal direction and the vertical direction with respect to the cell corresponding to the G light, as described in FIG. 3C. Then, the cells are opened one by one so as to complement the corresponding cells of the R light, and the positions of the _{cells EH B are sequentially moved.}

Then, in step S10, the color hologram recording device 1 displays the hologram data (B optical data) corresponding to the cell EH to be written on the spatial light modulation means (SLM) 17. That is, the hologram recording control device 50 reads out the B optical data corresponding to the cell EH to be written from the storage means 53 by the B optical data display means 542 of the cell data display means 54 according to the instruction from the synchronization means 55. Output to SLM17.

After that, in step S11, the color hologram recording device 1 irradiates the cell EH to be written with the object light and the reference light, and records the interference fringes. That is, the hologram recording control device 50 opens the shutter 110 _{B of the light source 10 B} that emits a blue laser beam by the light source control means 51 according to the instruction from the synchronization means 55, and irradiates the laser beam.
As a result, the blue laser light separated by the optical path separating means 13 is irradiated to the cell EH to be written as the object light and the reference light, respectively, and the interference fringes are recorded. After the irradiation for a predetermined time for recording the interference fringes is completed, the light source control means 51 _{closes the shutter 110 B} and stops the irradiation of the laser beam.

Then, in step S12, the color hologram recording device 1 determines whether or not the recording of the hologram recording medium H in the cell EH targeting the blue color is completed by the synchronization means 55.
Here, when the recording to the cell EH targeting blue is not completed (No), the color hologram recording device 1 returns to step S9 and continues the operation. On the other hand, when the recording to the cell EH targeting blue is completed (Yes), the color hologram recording device 1 ends the operation.

By the above operation, the color hologram recording device 1 can generate a color hologram by writing (exposure) twice on the hologram recording medium H. Further, the color hologram recording device 1 shifts the cells to be written by the R light and the B light by 1/2 cell with respect to the cells to be written by the G light, and records the hologram during image reproduction. The cell boundaries can be made inconspicuous in.

Although the configuration and operation of the color hologram recording device 1 according to the embodiment of the present invention have been described above, the present invention is not limited to this embodiment.

<Modification example 1>
Here, the R optical data and the B optical data are individually stored in advance in the storage means 53. However, since the cells for R color and the cells for B color are in a complementary relationship, the R optical data and the B optical data are stored in advance as one hologram data (RB optical data) for the hologram recording medium H. You may leave it.

In this case, the R optical data display means 541 and the B optical data display means 542 can be used as one RB optical data display means. Then, the synchronization means 55 instructs the cell position control means 52 to move the hologram recording medium H on a cell-by-cell basis to the recording medium moving means 20. Further, the synchronization means 55 instructs the RB optical data display means to display the hologram data (RB optical data) on the cell to be written in synchronization with the movement of the cell. _{Then, the synchronization means 55 alternately opens the shutters 110 R} and 110 _B for each color (RB) to be written to the light source control means 51 in synchronization with the movement of the cell, and the red laser light and the blue laser Instruct to irradiate with light alternately.

<Modification 2>
In addition, here, as shown in FIG. 3 (b), (c) , the write target opening the cell EH _B for the cell EH _R and B color for R color, respectively, by horizontal and vertical 1 cells It was the cell of. However, the arrangement of the cells is not limited to this. For example, FIG. 5 shows an example thereof.

5 (a) shows a green writing target cells (G) (cell EH _G for G color), which is similar to FIG. 3 (a).
As shown in FIG. 5 (b), for the red hologram data corresponding to the (R) (R light data), allocates the write target cell EH (cell EH R for R _color) open by vertically 1 cells .. The position of the cell EH _R is the cell EH _G, and position shifted half cell content horizontally and vertically, respectively. In FIG. 5 (b), shows the cell boundaries EH _G by a broken line.

Further, as shown in FIG. 5C, for the hologram data (B optical data) corresponding to the blue color (B), the cell EH to be written (cell EH B for color _B ) is opened vertically one cell at a time. To assign. Further, the position of the _{cell EH B is set to be} a position shifted horizontally and vertically by 1/2 cell with respect to _{the cell EHG G} , and is a position to complement _{the cell EHR of the R optical data.} In FIG. 5 (c), the represents the boundary of the cell EH _G by a broken line.
Here, the cell EH _R and cell EH _B, respectively, by opening one cell in the vertical direction in a complementary manner has been a write target, of course, each opening one cell in the horizontal direction, complementarily write target It doesn't matter.

<Modification example 3>
Further, here, the interference fringes were recorded by shifting the cells corresponding to the R optical data and the B optical data by 1/2 cell with respect to the cells corresponding to the G optical data. However, the cells corresponding to the R optical data and the B optical data may not be shifted. Even in this case, since the hologram recording medium is overwritten only twice in the same area, it is possible to suppress a decrease in diffraction efficiency during hologram reproduction.

<Reference example>
Here, the color hologram recording device 1 uses the spatial light modulation means 17 to generate object light from hologram data generated by a computer-synthesized hologram or the like.
However, the present invention can also be applied to a device that generates a hologram using the object light of a real object.

As a reference example, a color hologram recording device 1B that generates a color hologram using the object light of a real object will be described with reference to FIG.
As shown in FIG. 6, the color hologram recording device 1B includes a light source 10, a light source switching means 11, and the optical path separating means 13, a mirror 15 ₍₁₅ 1, 15 _2), and a magnifying lens 30, a magnifying optical system 31 And. Except for the magnifying lens 30 and the magnifying optical system 31, it is the same as the color hologram recording device 1 described with reference to FIG.
However, the light source 10 in the light source switching means 11 is manually switched via a switch or the like.

Magnifying lens 30, the laser beam reflected by the mirror 15 _2, it is to irradiate in the enlarged view of the object O.
Magnifying optical system 31, the laser beam reflected by the mirror 15 ₁ and converts it into a parallel beam the size of the hologram recording medium H.
As a result, the interference fringes can be recorded on the hologram recording medium H by the reference light emitted from the magnifying optical system 31 and the object light reflected by the object O.

However, depending on the color of the laser beam, the mask M is attached to both hologram surfaces of the hologram recording medium H as needed.
Here, when recording the interference fringes by the laser beam of the G light, the operator opens the shutter 110 _G of the _{light source 10 G without attaching masks to both sides of the hologram recording medium H.} As a result, the interference fringes of the G light are recorded on the hologram recording medium H by the reference light of the G light and the object light.

Further, when recording the interference fringes by the laser beam of the R light, the operator passes through a half region of the G light as described in FIG. 3 (b) and blocks the other region of the mask M of the chess pattern. the by attaching to face both sides of the hologram recording medium H, opens the shutter 110 _R of the light source 10 _R.
Further, when recording the interference fringes by the laser light of the B light, the operator passes through the region complementing the R light in a half region of the G light as described in FIG. 3 (c) and other regions. the mask M chess pattern for blocking and sticking to face both sides of the hologram recording medium H, and opens the shutter 110 _B of the light source 10 _B.
At this time, the size of the region through which the light of the mask M passes may be about the same as that of the cell of the color hologram recording device 1.

As a result, when the color hologram recording device 1B records the interference fringes on the hologram recording medium H, the interference fringes using the G light and the R light and the G light and the B light are generated at any position of the hologram recording medium H. Only one of the interference fringes using the above is recorded, and a hologram in which a decrease in diffraction efficiency is suppressed can be generated.

1 Color hologram recording device 10 Light source 11 Light source switching means 12 1/2 Wave plate 13 Optical path separation means 14 Spatial filter 15 Mirror 16 Optical path changing means (PBS)
17 Spatial Light Modulation Means (SLM)
18 Unnecessary light removing means 19 Reduction optical system 20 Recording medium moving means 50 Hologram recording control device (control means)
51 Light source control means 52 Cell position control means 53 Storage means 54 Cell data display means 55 Synchronization means

Claims (4)

A color hologram recording device that records interference fringes of RGB colors, which are the three primary colors, on a hologram recording medium in cell units.
A light source switching means for switching and emitting light from any of the RGB laser light sources of each color,
An optical path separating means for separating light emitted by switching by the light source switching means into two optical paths, and an optical path separating means.
Spatial modulation means that modulates one of the separated lights as object light using hologram data,
A recording medium moving means for moving a cell to be written on the hologram recording medium to an irradiation position where the object light and the reference light which is the other light separated by the optical path separating means overlap.
The recording medium moving means is driven for each of the RGB colors, the hologram data corresponding to the cell to be written is displayed on the spatial modulation means, and the laser beam of the corresponding color is switched to the light source. It is equipped with a control means for emitting light by means.
The control means
When recording interference fringes for G color, all cells are targeted for writing.
When recording the interference fringes for the R color, the boundaries of the cells for the R color do not overlap with the boundaries of the cells for the G color to be written when recording the interference fringes for the G color, and the cells are spaced one by one. The cell to be written is targeted
A color hologram recording apparatus characterized in that when recording interference fringes for B color, a cell that is not a writing target at the time of recording interference fringes for R color is targeted for writing. A color hologram recording device that records interference fringes of RGB colors, which are the three primary colors, on a hologram recording medium in cell units.
A light source switching means for switching and emitting light from any of the RGB laser light sources of each color,
An optical path separating means for separating light emitted by switching by the light source switching means into two optical paths, and an optical path separating means.
Spatial modulation means that modulates one of the separated lights as object light using hologram data,
A recording medium moving means for moving a cell to be written on the hologram recording medium to an irradiation position where the object light and the reference light which is the other light separated by the optical path separating means overlap.
The recording medium moving means is driven for each of the RGB colors, the hologram data corresponding to the cell to be written is displayed on the spatial modulation means, and the laser beam of the corresponding color is switched to the light source. It is equipped with a control means for emitting light by means.
The cell is a region that divides the hologram recording medium into a horizontal direction and a vertical direction.
The control means
When recording interference fringes for G color, all cells are targeted for writing.
When recording the interference fringes for the R color, the cells for the R color are shifted by 1/2 cell in the horizontal and vertical directions with respect to the cells for the G color to be written at the time of recording the interference fringes for the G color, respectively. , The cells that are spaced one cell at a time are targeted for writing.
A color hologram recording apparatus characterized in that when recording interference fringes for B color, a cell that is not a writing target at the time of recording interference fringes for R color is targeted for writing. A space modulation means that modulates one light that separates the laser light into two optical paths as object light, and an irradiation position where the reference light, which is the other separated light, and the object light overlap, and the writing target of the hologram recording medium. A color hologram manufacturing method for recording interference fringes of RGB colors, which are the three primary colors, on a hologram recording medium with a color hologram recording device provided with a recording medium moving means for moving the cells.
G-color cells are assigned to the hologram surface of the hologram recording medium without intervals, and G-color hologram data corresponding to the G-color cells is displayed on the spatial modulation means to display a G-color laser. G light recording process that emits light and
The cells for R color and the cells for B color are complementaryly and alternately assigned to the hologram surface of the hologram recording medium, and the corresponding hologram data for R color is assigned to the cells for R color. The R color laser beam is emitted by displaying on the space modulation means, and the corresponding hologram data for the B color is displayed on the space modulation means for the B color cell to emit the B color laser light. and RB optical recording step to emit light, only including,
In the RB optical recording step, the cell for the R color and the cell for the B color so that the boundary between the cell for the R color and the cell for the B color does not overlap the boundary of the cell for the G color. A color hologram manufacturing method characterized by writing. A space modulation means that modulates one light that separates the laser light into two optical paths as object light, and an irradiation position where the reference light, which is the other separated light, and the object light overlap, and the writing target of the hologram recording medium. A color hologram manufacturing method for recording interference fringes of RGB colors, which are the three primary colors, on a hologram recording medium with a color hologram recording device provided with a recording medium moving means for moving the cells.
G-color cells are assigned to the hologram surface of the hologram recording medium without intervals, and G-color hologram data corresponding to the G-color cells is displayed on the spatial modulation means to display a G-color laser. G light recording process that emits light and
The cells for R color and the cells for B color are complementaryly and alternately assigned to the hologram surface of the hologram recording medium, and the corresponding hologram data for R color is assigned to the cells for R color. The R color laser beam is emitted by displaying on the space modulation means, and the corresponding hologram data for the B color is displayed on the space modulation means for the B color cell to emit the B color laser light. and RB optical recording step to emit light, only including,
The cell is a region that divides the hologram recording medium into a horizontal direction and a vertical direction.
The RB optical recording step is characterized in that the cell for the R color and the cell for the B color are shifted by 1/2 cell in the horizontal direction and the vertical direction with respect to the cell for the G color, respectively. Color hologram manufacturing method.

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