JPH05150701A - White light reproducing hologram recorder - Google Patents

Abstract

PURPOSE:To improve calculation efficiency and to improve the quality of white light reproducing three-dimensional images by providing a hologram calculating section and a scanning recording section which forms the hologram by recording interference fringe patterns on a recording medium while scanning the recording medium. CONSTITUTION:The recorder consists of a real image calculating section 12 for a three- dimensional object 11 desired to be displayed as the hologram, the hologram calculating section 17 for calculating the interference fringe pattern by superposing the real image as object light on reference light 18 and the scanning recording section 19 for recording the image on a photosensitive material or the like by using a laser beam. Further, the real image calculating section 12 consists of a diffracted image calculating section 13 for calculating the diffracted patterns of the three-dimensional object 11, a hologram calculation section 14 for calculating the interference fringe patterns by adding reference light 15 and a real image reproducing section 16 for reproducing the real image from the interference fringes. The reconstructed image is projected to the hologram surface of the hologram calculating section 17 and the interference fringe patterns are calculated by superposing this image on the reference light 18 and thereafter, the hologram hologram which can be basically reconstructed with white light is formed if the scanning and recording are executed by the laser scanning recording section 19.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a white light reproducing hologram recording apparatus for calculating, scanning and recording a white light reproducing hologram pattern.

[0002]

2. Description of the Related Art Computer holograms include those created by calculating a diffraction image of an object and those created by calculating interference fringes. The former divides the hologram surface into small cells, calculates the diffracted light (represented by complex amplitude) from the object at a representative point in the cell, and creates an aperture in the cell according to the amplitude value and phase value of this value. It is made by providing.

FIG. 2 is an example of this type of computer hologram, in which 21 is a cell formed by dividing the hologram surface into several cells, and 22 is an opening in the cell. The height W of the opening 22 is determined according to the amplitude value, and the phase φ
The distance P between the center of the opening 22 and the center of the cell 21 is determined according to the value of. Moreover, the shaded portion 23 is opaque. Such cells 21 are gathered together to form a computer hologram, and object light can be reproduced by irradiating coherent light (AWLohmann & DPParis:
“Binary Fraunhofer holograms, generated by cmpute
r ”, Appl.Opt., Vol.6, No.10, pp.1739-1748 (Oct. 1
967)).

On the other hand, the latter type of computer hologram for calculating interference fringes, like the optical hologram,
It is created by overlapping the diffraction image of the object and the reference light and determining the transmittance of the hologram cell according to the intensity of the interference fringes of the two. In the former type of computer hologram,
The center of the aperture in the cell and the position of the representative point where the phase is calculated are often displaced, resulting in poor image quality compared to the reproduced image obtained from the optically produced hologram. Is expressed in the form of interference fringes, so that a reproduced image with good image quality can be obtained with no phase error.

Such a conventional type computer hologram does not exist as an optical hologram produced by interfering coherent light beams does not require an optical system or a seismic isolator, and an arbitrary wavefront can be obtained by calculation. It has the advantage that it can also create holograms of objects. On the other hand, however, it takes a lot of time to calculate the diffraction image and a huge memory is required to store the hologram data, so that it is difficult to make a hologram capable of reproducing a three-dimensional image or a type capable of reproducing white light. In addition, there is a drawback that the image quality is poor, and further that a procedure for reducing the hologram is required for reproduction.

[0006]

As described above, in the conventional computer hologram, the calculation efficiency is low (the calculation time is long, the memory amount is large), the image quality is poor (there is a phase error, the reproduction of white light is unsuccessful). Yes, it is difficult to reproduce a three-dimensional image), and it is necessary to reduce the hologram by photographic technology.

The present invention makes it possible to shorten the calculation time and save the amount of memory while making the most of the advantages of computer holograms, such as simple equipment and the ability to create holograms of fictitious objects other than existing objects (even from CG images). Therefore, it is an object of the present invention to provide a white light reproduction hologram pattern recording apparatus capable of improving calculation efficiency and obtaining a three-dimensional reproduction image having excellent image quality and a reproduction image by white light.

[0008]

In order to solve the above-mentioned problems, the present invention calculates a real image of a three-dimensional object and further calculates an interference fringe pattern generated by superposition of the real image wavefront of this real image and reference light. The basic feature is that a hologram is formed by scanning and recording on a recording medium using a photosensitizer or the like.

Further, in the present invention, a set of one or a plurality of scanning lines is set as one block in the scan recording, and the procedure for performing the scan recording by calculating only the interference fringe pattern of the portion corresponding to one block is performed for each block. It is characterized in that the entire interference fringe pattern is scanned and recorded by repeating the above procedure or performing the procedure in parallel for a plurality of blocks. In this case, it is preferable that the calculation of the interference fringe pattern of one block and the scan recording be executed in parallel.

Furthermore, the present invention requires 3 in calculating the real image.
Characterized by calculating a real image of a three-dimensional object from one of three patterns of the diffraction pattern of the three-dimensional object or the interference pattern of the diffraction image pattern and the reference light or the real image of the interference fringe pattern To do. In this case, in the calculation of the interference fringe pattern or the real image reproducible part of the interference fringe pattern used to reproduce the real image, the incident angle of the diffraction image and the incident angle of the reference light are made equal, and the interference fringe pattern or the real image of the interference fringe pattern can be reproduced. It is desirable to reduce the sample density required for the part.

The diffraction image pattern of the three-dimensional object or the incident angle of the diffraction image is defined as one of the three patterns of the interference fringe pattern of the diffraction image pattern and the reference light or the real image reproducible portion of the interference fringe pattern. When reproducing a real image of a three-dimensional object, it is desirable to provide a thin slit and use the reproduced real image calculated only from the data of this slit portion. In this case, in the calculation of the interference fringe pattern used for reproducing the real image or the real image reproducible portion of the interference fringe pattern, if the incident angle of the diffraction image and the incident angle of the reference light are equal,
The sample density required for the interference fringe pattern or the real image reproducible portion of the interference fringe pattern can be reduced.

Further, a three-dimensional object light (one line of three-dimensional object light) parallel to the slit coming from the position of the slit used for reproducing the real image from a certain angle (elevation angle) direction produces a diffraction image at the slit position. The interference fringe pattern of the pattern or the diffraction pattern and the reference light or the reproduced real image calculated from the real image reproducible portion of the interference fringe pattern can be used to scan and record the interference fringe pattern for one block.

A fixed angle direction from the slit position is discretized, and each one line of three-dimensional object light obtained from the discretized angle direction and each one block of one block calculated from one line of three-dimensional object light. It is desirable that the positional relationships of the interference fringe patterns of 1) correspond to each other.

In the calculation of the interference fringe pattern used for reproducing the real image or the real image reproducible portion of the interference fringe pattern, it is desirable to make the incident angle of the object light and the reference light incident on the slit equal.

[0015]

[Function] A hologram created by superimposing a real image of an object and a reference beam is a type of hologram that can be reproduced with white light. If scanning recording is performed using a laser beam that is narrowed down, direct recording of the hologram is possible Time reduction processing can be omitted. That is, it is not necessary to reduce the hologram at the time of reproduction, and a hologram capable of reproducing white light and reproducing three-dimensionally can be produced.

Further, in real image reproduction, a hologram with a relatively low resolution is used instead of a hologram with a high resolution in which the angle between the diffracted light and the reference light is large, or an interference fringe in which the angles of the diffracted light and the reference light are in the same direction. By using the pattern (hologram pattern), the calculation time can be shortened and the memory can be saved.

Further, by performing scanning recording by calculating only the interference fringe pattern corresponding to one block in which one line or several lines are put together in scanning recording, it becomes possible to save memory, and moreover, one line or one block can be saved. By executing the calculation of the interference fringe pattern and the scan recording in parallel, the hologram production time can be shortened.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 is a block diagram of an image hologram production system shown as a basic embodiment of a hologram recording apparatus of the present invention, in which a three-dimensional object 11 desired to be displayed as a hologram and a real image calculation unit of the three-dimensional object. 12 and real image are used as object light and superposed with reference light 18 to calculate interference fringe pattern Hologram calculator 17 and laser light that is narrowed down according to the intensity of the interference fringe pattern is used for scanning and recording on a recording medium such as a photosensitive agent. And a scan recording unit 19. Further, the real image calculation unit 12 includes a diffraction image calculation unit 13 that calculates a diffraction image pattern of a three-dimensional object, a hologram calculation unit 14 that calculates a fringe pattern by adding a reference beam 15, and a real image reproduction unit that reproduces a real image from interference fringes. It consists of 16. As a real image reproducing method, there is a method of calculating based on the image forming mechanism of the lens, but in this embodiment, a method of utilizing the real image reproducing method from the hologram will be described.

The hologram used for reproducing a real image in an optical system is a hologram obtained by superimposing an object light from a three-dimensional object and a reference light such as a plane wave or a spherical wave to form an interference fringe, and exposing it to a photosensitive agent. .. In this case, the hologram needs to be made with a large difference between the incident angle of the object light and the incident angle of the reference light on the hologram surface in order to effectively separate the virtual image and the real image generated when reproduced by laser light. .. As a result, the resolution of the hologram pattern is very high. When the process of reproducing the real image is realized by calculation, if the process in the optical system is performed as it is, the efficiency becomes very poor in terms of calculation time and memory amount.

Therefore, in this embodiment, a real image is reproduced from a hologram having a low resolution to improve efficiency. That is, after the diffraction image calculation unit 13 calculates the diffraction image pattern of the three-dimensional object, the hologram calculation unit 14 calculates the reference light 15 in the same direction as that of the diffraction image pattern. Only the component (real image component) to be calculated is calculated, and the real image reproducing unit 16 reproduces the real image from this real image component. Since the pattern of the real image component is expressed by complex amplitude and the resolution is considerably reduced compared to the hologram pattern of the optical system, the memory amount is considerably reduced and the calculation time is also significantly reduced. The object light on the hologram surface is O (x, y), and the reference light is R (x, y).
Then, the hologram pattern I (x, y) is I (x, y) = | O (x, y) + R (x, y) | ² = | O (x, y) | ² + | R (x, y) | ² + O (x, y) R (x, y) ^* + O (x, y) ^* R (x, y) (1), of which the fourth term is the real image reproduction component. *
Means complex conjugate. Another possible real image reconstruction method is the diffraction pattern (complex amplitude) before calculating the interference fringes.
It is also possible to reproduce a real image by using, and in this case as well, it is possible to reduce the memory amount and the calculation time. The above method of calculating the diffraction pattern and the method of reproducing the real image have already been formulated (detailed references in optics and literature). For example, taking a case where a Fresnel hologram is calculated using a two-dimensional image as an object, Fresnel diffraction image data can be obtained by the following algorithm.

(1) A two-dimensional image is represented by sample values.
The sample density depends on the performance of the system that creates the hologram and the degree of image quality required for the reproduced image from the hologram, but about 8 to 10 lines / mm is sufficient to obtain a reproduced image with good image quality. Let's do it.

(2) The Fresnel diffraction image pattern (two-dimensional) created on the hologram surface by the light emitted from each sample point is calculated. This calculation may be thought of as calculating the wavefront of the light emitted from the point light source, or assuming that there is a minute aperture at the position of the sample point, and irradiating a plane wave with an intensity equivalent to the sample value from behind the aperture. It may be considered that the wavefront of light from the minute aperture at the time is calculated, and a two-dimensional Fresnel diffraction image is obtained from each sample point. Fresnel integrals are used for these calculations (details can be found in optical reference books and literature).

(3) Finally, if all Fresnel diffraction image patterns from each sample point are added together, a Fresnel diffraction image pattern for a two-dimensional object can be obtained.

The Fresnel diffraction pattern for a three-dimensional object is also expressed as a sample value in the three-dimensional space (a sample value is assigned to each point of the three-dimensional lattice) in the same manner as in the case of the two-dimensional object, or the surface of the three-dimensional object is It is sufficient to express the sample value and add the Fresnel diffraction pattern from each sample point. At this time, the hidden surface can be erased. The diffraction image calculation unit 13 may perform the Fresnel transform of the above method, and when calculating the real image from the real image component of the hologram,
Fresnel conversion of this real image component may be performed (if the incident angles of the object light and the reference light are different, the signal obtained by multiplying the real image component by the reproduction light in the opposite direction to the reference light may be Fresnel converted). When reproducing a real image from a diffraction image pattern, Fresnel conversion is performed after inverting the phase of the diffraction image pattern.

The real image reproduced in this way is projected on the hologram surface of the hologram calculation section 17, the interference fringe pattern is calculated by superimposing it on the reference beam 18, and then the laser scanning recording section 19 performs scanning recording. Basically, it is possible to make an image hologram capable of reproducing white light.

In the hologram calculators 14 and 17, there are two points to be considered in calculating the interference fringe pattern. The first point is three types of signals (object, diffraction image, interference fringe)
The different sample densities needed to represent each are different. For example, a sample density of about 8 to 10 lines / mm is sufficient for expressing an object, but several tens to 100 lines / mm for a diffraction pattern, and at least several hundred lines / mm for an interference fringe pattern. It seems that the above (1,000 lines / mm or more in some cases) is necessary, and the sample densities are considerably different. In the end, a calculated value with the density of the interference fringe pattern is required, but if all the calculations are performed with this density, a huge amount of memory is required, which is not convenient.

The second point is that it takes a considerable time to calculate the diffraction pattern. In such a situation, in order to minimize the calculation time and reduce the required memory amount, the sample density of the diffraction pattern is calculated as small as possible, and the sample value of this diffraction pattern is interpolated (linear density conversion Then, if the interference fringe pattern is calculated by increasing the sample density of the interference fringe pattern, the calculation amount of the time-consuming diffraction image pattern, that is, the calculation time is reduced, and the memory amount is also small.

Therefore, in the hologram apparatus of this embodiment, the diffraction pattern is calculated at a sample density of about several tens of lines / mm, and when the interference fringe pattern is calculated, the sample points of the diffraction pattern for two lines are calculated. To interpolate the data between the sample points to increase the required density, and superimpose it on the reference light to obtain the final interference fringe pattern for scanning and recording. As a result, it is possible to realize a system capable of reducing the calculation time and saving the memory without storing the interference fringe pattern having a high sample point density.

Next, the sample value interpolation of the diffraction pattern will be described. The interpolation process is a process for matching the sampling density of the diffraction image data with the sampling density of the interference image data to be finally recorded, and is basically the same as the linear density conversion process performed in general image processing. .. Here, consider a case in which a line memory for two lines is provided and two-dimensional interpolation processing is performed by electronic processing for both main scanning and sub-scanning.

FIG. 3 shows a diffraction image pattern for 2 lines and 2 lines.
It is the example which explained the procedure of the dimensional interpolation processing method. The white circles are the i-th and i + 1-th sample points of the diffraction pattern, and the black triangles and black squares are the interpolated data. In the case of interpolation, first, the sampling point of the i-th line is used to determine the interpolation point (displayed by a black square) in the main scanning direction (example of 3-point interpolation), and the value is calculated to calculate the interference fringe pattern. One line of diffraction image data required for calculation is constructed. The interference fringe data for one scanning line is calculated from the diffraction image data for this one line, and after performing the scan recording, or while performing the scan recording, the diffraction image pattern corresponding to the next scanning line is calculated. The diffraction image data corresponding to the next scanning line is i
Interpolation points (displayed by black triangles) are determined in the sub-scanning direction between two lines at the sample points (white circles) of the 1st diffraction image line and the (i + 1) th diffraction image line (example of 3-point interpolation). , The value of the interpolation point closest to the i-th diffraction image line that has already been scanned and recorded is calculated. Then, an interpolation point (displayed by a black square) in the main scanning direction is determined (example of three-point interpolation), and a sample value thereof is calculated to obtain diffraction image data for the next scanning line. If this procedure is continued up to the i + 1st diffraction image line, 2 of the part sandwiched between the ith and i + 1th
Dimensional interpolation is completed. This process is repeated for all diffraction image lines. The interpolation process in this description is basically one-dimensional interpolation, and conventional interpolation processes such as simple linear interpolation, Lagrange interpolation, and spline interpolation can be used, but the process of interpolating data is not limited to these methods. It goes without saying that anything is fine.

Furthermore, in this description, an example in which the interpolation processing is performed using two lines has been described, but it is also possible to use more lines.

The calculation method of the interference fringe pattern obtained by superimposing the interpolated diffraction image data and the reference light (plane wave or spherical wave) is as follows. 2 of diffraction pattern
Diffraction image data with high resolution for each scanning line (not one line of the diffraction image pattern, but one line of the interference fringe pattern to be scan-recorded) obtained by the interpolation processing using the data for the line, and the plane wave or Reference light of spherical wave 18
The data of and are added independently at each sample point, and the absolute value thereof is squared. As a specific calculation method, the interference fringe pattern is obtained by multiplying the real part and the imaginary part of the interpolated diffraction image data and the reference light data, and adding the respective multiplication results. Since the amplitude of this interference fringe pattern also fluctuates in the negative direction, after multiplying the interference fringe data with an appropriate constant to adjust the amplitude value of the interference fringe pattern, the bias constant is further added to the interference fringe pattern. Have only positive amplitude values. This is because only positive values can be recorded when performing scan recording on the recording medium.

As described above, the interference fringe pattern for one scanning line can be calculated. The interference fringe pattern of the next scanning line can also be calculated by repeating the same processing from the interpolated diffraction image data corresponding to this scanning line position.

The interference fringe data for one scanning line obtained from the hologram calculation section 17 is recorded on the recording medium by the laser scanning recording section 19. At this time, in order to correct the gradation of the exposure characteristics of the recording material and the modulation characteristics of the recording light source, and to suppress the noise generation due to the distortion of the gradation characteristics of the interference fringe pattern that is finally created, gradation correction is performed. It is desirable to perform processing. In the conventional optical interference method, it was difficult to control the gradation property because it depended on the characteristics of the recording material itself, but the gradation correction processing according to the present invention is easy to control, and it is great for improving image quality. There are merits.

The corrected interference image data subjected to gradation correction is
It is written on the recording material by the scanning recording unit 19. To create an interference fringe type hologram, 1000 lines / mm
To 3000 lines / mm may be required. Here, FIG. 4 shows a configuration of a rotary drum type scanning system and a scanning recording unit 19 in which multiple beams are formed to increase the recording speed.

In FIG. 4, the recording material is mounted on the drum 100. The drum 100 is a drum rotation driving motor 1
01 rotates at a constant speed. This rotation direction X corresponds to the main scanning direction. The rotation state of the drum 100 is monitored by the rotary encoder 102 attached to the rotation shaft, and the clock corresponding to the rotation is divided by the frequency dividing circuit 1.
04, further sent to the clock control circuit 105, and fed back to the write timing of the recording data.

On the other hand, the sub-scanning is performed by moving the recording light source. Three LDs (semiconductor lasers) 107, 108, and 109 are attached to the recording light source unit 106 at intervals, and the respective light beams are focused lenses 110 and 11.
At 1,112, the spot size on the recording surface is narrowed down so that it is on the order of wavelength. The interval between the LDs 107 to 109 is a value obtained by dividing the recording width in the sub-scanning direction Y into three equal parts, and is basically adjusted so as to satisfy a positive multiple of the scanning line pitch. Should be satisfied. The recording light source unit 106 is moved and scanned in the sub-scanning direction Y by a ball screw 113 and a light source driving motor 114 that rotates the ball screw 113. As a result, the scanning ends at the moving distance of ⅓ of the total recording width in the sub-scanning direction Y.

A drum rotation driving motor 101 for main scanning and a light source driving motor 114 for sub scanning.
Are driven by motor drive circuits 115 and 116, respectively. This drive control is controlled in synchronization with the control signal from the control circuit 117 and the clock from the clock control circuit 104.

The corrected interference image data to be recorded is input to the buffer circuit 118 in three channels in parallel. The print data fetched by the buffer circuit 118 is adjusted by the digital-analog converter 11 at each scanning driving timing.
Sent to 9. 3 with this digital-analog converter 119
By supplying the recording data signal converted into the analog signal in the channel parallel to the light source array driving circuit 120, the light intensity modulation of each of the LDs 107 to 109 is performed and the two-dimensional interference image pattern is combined with the multi-beam scanning. Recorded. The recording controller 121 controls the entire multi-beam scanning recording in response to an instruction from the host controller.

Thus, the recording of the hologram is completed. The written recording material is subjected to processing such as development and fixing as necessary, and a final hologram is completed.
Although the structure of this processing of the recording material differs depending on the recording material used, in configuring the hologram recording device,
It is better not to require recording material processing such as development and fixing. For example, if a photochromic material using photochemical change, an electro-optical material such as LiNbO ₃ that causes a change in refractive index by light, or an amorphous semiconductor whose light blackening and refractive index change is used, no recording material treatment is required.
Recording materials that can be handled by a relatively simple dry process include thermo-plastics that are used in electrostatic recording and thermal development.
Photopolymer treated with UV and heat (monomer, initiator,
Polymer matrix type including sensitizing dye) and the like.
Conventionally used silver salt photosensitive materials, dichromated gelatin, photoresists and the like require a wet process, but if they can be incorporated in terms of equipment and system, there is no problem from the point of the present invention.

(Embodiment 2) FIG. 5 is an embodiment in which the present invention is applied to a rainbow hologram. In the real image calculation unit 12, the direction designation unit 3 of the diffracted light is provided before the diffraction image calculation unit 13.
1 is different from that of the first embodiment. This type of hologram has a parallax only in one direction because the real image is reproduced from the interference fringes of the thin slit portion, but the first embodiment has a parallax.
It is characterized by less blurring and better image quality than the image hologram.

In order to form a rainbow hologram by an optical method, a hologram is once formed by an ordinary method, a thin slit is provided in this hologram, a real image is reproduced from the slit portion, and then the reproduced real image is made into a hologram again. It is common. According to this procedure,
It is clear that it is extremely inefficient in terms of computation time and memory. Therefore, in this embodiment, the efficiency of calculation is improved by utilizing the fact that the finally obtained hologram basically has a parallax only in one direction. That is, the hologram used for reproducing the real image by the direction designating unit 31 of the diffracted light in the real image calculation unit 12 may be a hologram having only one direction of parallax, and may be calculated for each line. A specific calculation method when a two-dimensional plane is used as an object will be described below.

(1) Determine a line (parallel to the slit) that intersects with the two-dimensional object plane when a ray parallel to the slit is emitted from the slit at a constant angle (elevation angle).

(2) A diffracted image pattern, an interference fringe pattern, or a real image reproducible portion of the interference fringe pattern which one line of the two-dimensional object plane causes at the slit position is calculated. Since this calculation is only for one line, this method has a smaller resolution than the method of calculating the diffraction pattern as the sum of the diffracted light reaching the slit position from the entire object, as in the case of the optical method. Calculation of patterns is allowed.
Further, if the direction of the reference light used for the calculation of the interference fringes is set to be the same as the direction of the object light for one line, the calculation of the interference fringe pattern can be performed with a small resolution, so that the calculation time and the memory amount can be reduced.

(3) A real image for one line is reproduced from the diffraction image pattern or the interference fringe pattern of the slit portion or the real image reproducible portion of the interference fringe.

(4) Interpolation of the reproduced real image for one line,
After increasing the sample density to the resolution required for the interference fringe pattern, superimposing the reference light, calculating the interference fringe pattern,
Perform laser scanning recording. A plane wave is often used as the reference light. The number of scanning lines obtained at this time depends on the incident angle of the plane wave of the reference light. For example, when the incident angle of the plane wave is set in the vertical direction (parallel to the slit), interference fringes are formed in the vertical direction, so that it is necessary to record many scanning lines. That is, the object image corresponding to the width of one line is
Produces many scan lines in the same width. On the other hand, if the incident angle of the plane wave is in the left-right direction (perpendicular to the slit), 1
One scan line can fill the width of one line.

(5) Constant angle from the slit position (elevation angle)
Change the value of and repeat the calculation from (1) to (4) to complete the rainbow hologram. How to change the elevation value,
The angles may be discretized at equal intervals, or may be discretized at unequal intervals in which the discretization angles are changed between a portion having a large angle and a portion having a small angle. Alternatively, the elevation angle may be determined so that the width of the object image for one line is constant, instead of discretizing by angle. It is sufficient that the density of discretization is about 8 to 10 lines / mm.

In the above description, a two-dimensional image is taken as an example of an object, but a three-dimensional object can be calculated in the same manner.

(Embodiment 3) FIG. 6 is an embodiment in which the present invention is applied to a holographic stereogram, in which a parallax image calculation unit 30 is inserted before the real image reproduction unit 30, and the parallax image calculation unit 12 further includes a parallax image. Image switching unit 32 and real image addition unit 3
3 has been added. First, various angles for observing the three-dimensional object are changed, and the two-dimensional image (parallax image) at each angle is calculated by the parallax image calculation unit 30. This is the same as taking a picture at a different angle. Next, similarly to the second embodiment, from one line of the first parallax image corresponding to the elevation angle direction from the slit position,
Calculate the diffraction image pattern or interference fringe pattern at the slit position or the real image reproducible part of the interference fringe pattern,
Reproduce the real image. The calculation method at this time is the same as that of the second embodiment. Next, a real image is reproduced in the same manner using the second parallax image and added to the first real image. If this process is performed on all parallax images, a real image of a three-dimensional object can be obtained.

In the example of FIG. 6, the addition is performed in the stage of the reproduced real image in the real image adder 33. However, a part of the diffraction image pattern or the interference fringe pattern or the real image reproducible portion of the interference fringe pattern is arranged in the order of the parallax image. It is also possible to reconstruct a real image after reconstructing into a diffraction image pattern or an interference fringe pattern corresponding to one line or a real image reproducible portion of the interference fringe pattern.

Finally, the reference fringes may be added to calculate the interference fringe pattern, and scanning recording for one line may be performed. This procedure is performed by the diffracted light direction designating unit 31 in the direction of diffracted light (elevation angle).
Is repeated and repeated.

In the above embodiments, the number of slits is not limited to one, and if a plurality of slits are used, parallax occurs not only in the horizontal direction but also in the vertical direction, so that the appearance of a three-dimensional object can be made closer. Further, in order to colorize the hologram, the calculation procedure of Examples 1 to 3 is performed using three kinds of wavelengths of red, blue and green, and the interference fringe patterns are superposed on a recording medium capable of recording three color signals. It may be scanned and recorded together.

[0053]

As described above, according to the present invention, the calculation time can be shortened and the amount of memory can be reduced while utilizing the characteristics of the conventional computer hologram such that a hologram of an imaginary object can be created without requiring a complicated optical system. It is possible to improve the calculation efficiency by saving the cost and create a hologram capable of reproducing white light of a three-dimensional object having excellent image quality.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment in which a hologram recording device of the present invention is applied to an image hologram.

FIG. 2 is a diagram for explaining the relationship between cells and openings in a conventional computer hologram pattern.

FIG. 3 is an explanatory diagram of interpolation processing in the embodiment.

FIG. 4 is a diagram showing a configuration example of a scanning recording apparatus in the embodiment.

FIG. 5 is a block diagram showing an embodiment in which the hologram recording device of the present invention is applied to a rainbow hologram.

FIG. 6 is a block diagram showing an embodiment in which the hologram recording device of the present invention is applied to a holographic stereogram.

[Explanation of symbols]

11 ... Three-dimensional object 12 ... Real image calculation unit 13 ... Diffraction image calculation unit 14 ... Hologram calculation unit 15 ... Reference light 16 ... Real image reproduction unit 17 ... Hologram calculation unit 18 ... Reference light 19 ... Laser scanning recording device 21 ... Cell 22 ... Aperture 23 ... Opaque part 30 ... Parallax image calculation part 31 ... Diffracted light direction designating part 32 ... Parallax image switching part 33 ... Real image adding part 106 ... Recording light source unit 107-10
9 ... Semiconductor laser 110-112 ... Focusing lens 113 ... Ball screw

Claims (3)

[Claims] 1. A real image calculation means for calculating a real image of a three-dimensional object, and an interference fringe pattern calculation for calculating an interference fringe pattern between the object light and the reference light, using the real image calculated by this means as object light. A white light reproducing hologram recording apparatus comprising: a recording medium; and a scanning recording device that scans and records an interference fringe pattern calculated by this device on a recording medium. 2. The scanning recording means sets a set of one or a plurality of scanning lines for scanning recording as one block, and calculates only an interference fringe pattern of a portion corresponding to one block to perform scanning recording. 2. The white light reproduction hologram recording apparatus according to claim 1, wherein the entire interference fringe pattern is scanned and recorded by repeating each block or performing the procedure in parallel for a plurality of blocks. 3. The real image calculation means is one of three patterns of a diffraction image pattern of the three-dimensional object or an interference fringe pattern between the diffraction pattern and a reference light or a real image reproducible portion of the interference fringe pattern. The white light reproducing hologram recording apparatus according to claim 1, wherein a real image of the three-dimensional object is calculated from the above.