Hologram data display device, hologram data generation device, programs thereof, and display system

Abstract

To provide a hologram data display device that displays three-dimensional images with a compact configuration.SOLUTION: A hologram data display device 1 includes: an SLM array 10 which has multiple SLMs 10i arranged two-dimensionally to display hologram data 3; and a DOE 11 which is arranged so as to be apart from the SLM array 10 and on which light reconstructed from the hologram data 3 displayed on the SLM array 10 is incident. The hologram data 3 is the data that is previously generated through calculation in which object light modulated by a virtual DOE 21 having the characteristics opposite to the characteristics of the DOE 11 is interfered with reference light.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to holography, and more particularly to a hologram data display device, a hologram data generating device, and programs therefor, as well as a display system. [Background technology]

[0002] Holography is a technology that records and reproduces the wavefront of light as interference fringes. In principle, 3D images reproduced by holography can faithfully reproduce the light from an actual subject, so it is said that there is no mismatch between convergence and accommodation, which is a problem with stereograms (two-eye three-dimensional displays).

[0003] Computer Generated Hologram (CGH) is a method for generating hologram data, which is the basis of 3D images, by calculation. In the CGH method, the hologram is created by the interference of the wavefront (object light) from the subject and reference light, but not physically, but by calculation. The CGH method involves calculations of the propagation of the object light and the interference between the object light and reference light, as well as the generation of hologram data that matches the modulation method and number of gradations of the spatial light modulator (SLM) used for display.

[0004] The hologram data is displayed on the SLM. A 3D image is reproduced by illuminating the SLM with the reference light used in generating the CGH as the reconstruction illumination light. The viewing angle of the 3D image (the angle at which the 3D image can be observed) θ VA is limited by the diffraction angle due to the pixel structure of the SLM and can be expressed as the following equation (1).

[0005] θ VA =2sin -1 [λ / (2p)] … Equation (1)

[0006] Here, λ is the wavelength of the reconstruction illumination light, and p is the pixel pitch of the SLM. From equation (1), it can be seen that narrowing the pitch of the SLM is necessary to widen the viewing area of ​​a 3D image. Also, to display a large 3D image, it is necessary to increase the area of ​​the SLM. Here, if the number of pixels in the width direction of the SLM is N, x , the number of pixels in the height direction is N y Then, the width W and height H of the SLM can be expressed as the following equations (2) and (3), respectively.

[0007] W=pN x … Formula (2) H=pN y … Formula (3)

[0008] Therefore, to display 3D images with a wide viewing area and on a large screen, it is necessary to increase the number of pixels as well as narrow the pixel pitch. In recent years, research has been conducted on SLMs with narrow pixel pitches and a large number of pixels in order to display holograms with a wide viewing area (for example, see Patent Document 1). Research is also being conducted on realizing an increase in the number of pixels in the entire hologram data display device by arranging and applying multiple SLMs (for example, see Non-Patent Document 1). [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2019-144423 A [Non-patent literature]

[0010] [Non-Patent Document 1] Jin Li et al., “Holobricks: modular coarse integral holographic displays”, Light: Science & Applications 11, 57 (2022) Summary of the Invention [Problem to be solved by the invention]

[0011] However, when using a single SLM to narrow the pixel pitch and increase the number of pixels, it becomes difficult to arrange the circuits to drive the pixels as the number of pixels increases. In addition, the technology disclosed in Non-Patent Document 1 lays out a large optical system on a large workbench board in order to remove the gap between the SLMs. In other words, the conventional method of arranging multiple SLMs to realize an increase in the number of pixels for the entire display device requires a very large optical system.

[0012] The present invention has been made in consideration of the above-mentioned problems, and has an objective of providing a hologram data display device, a hologram data generating device, and their programs, as well as a display system, that display three-dimensional images with a compact configuration.

[0013] In order to solve the above problems, the hologram data display device of the present invention comprises an SLM array having a plurality of spatial light modulators arranged two-dimensionally and displaying hologram data, and a diffractive optical element arranged at a distance from the SLM array and onto which light reconstructed from the hologram data displayed on the SLM array is incident, and the hologram data is generated in advance by calculation of interfering object light modulated by a virtual diffractive optical element having characteristics opposite to those of the diffractive optical element with reference light.

[0014] With this configuration, the hologram data display device is composed of a combination of multiple SLMs and a diffractive optical element (hereinafter referred to as DOE). When an observer observes the SLM array without a DOE, the gaps between the SLMs are visible. On the other hand, when an observer observes the SLM array through a DOE, the wavefront of the reconstructed light is moderately scattered due to the DOE in front of the observer, and a three-dimensional image is seen as if there were no gaps between the SLMs. The hologram data display device does not require a large optical system, and its compact configuration makes it possible to conceal the gaps between the SLMs.

[0015] Furthermore, a hologram data generation device according to the present invention is a hologram data generation device that generates hologram data to be displayed on an SLM array of a hologram data display device having an SLM array having a plurality of spatial light modulators arranged two-dimensionally, and a diffractive optical element arranged at a distance from the SLM array, and is equipped with a memory unit and a processing unit, wherein the processing unit executes a first calculation process of generating object light from subject data, a second calculation process of propagating the object light to a virtual diffractive optical element, a third calculation process of calculating the object light modulated by the virtual diffractive optical element, a fourth calculation process of propagating the object light modulated by the virtual diffractive optical element to a virtual SLM array having a plurality of virtual spatial light modulators arranged two-dimensionally, and a fifth calculation process of causing the object light modulated by the virtual diffractive optical element to interfere with a reference light and generate hologram data, and the virtual diffractive optical element has the inverse characteristics of the diffractive optical element.

[0016] According to this configuration, the hologram data generating device can generate hologram data by performing calculations to propagate object light generated from object data and calculations to modulate the object light by a virtual DOE (diffractive optical element). Since the virtual DOE has the inverse characteristics of the real DOE arranged in the hologram data display device, the object light from which hologram data is reproduced on the hologram data display device side is equivalent to the object light modulated by the virtual DOE. On the hologram data display device side, the light from which this reproduced object light is modulated by the real DOE is equivalent to the object light generated by calculation from the object data. Therefore, when the SLM array is observed on the hologram data display device side through the real DOE, it is possible to reproduce a three-dimensional image that is the basis of the object data. Therefore, by displaying hologram data on the hologram data display device side, a three-dimensional image corresponding to the object data can be displayed on a large screen with a wide viewing area with a compact configuration.

[0017] The hologram data display device can be operated by a hologram data display program that causes a computer to function as each of the above-mentioned means. Furthermore, the hologram data generating device can be operated by a hologram data generating program that causes a computer to function as each of the above-mentioned means. Effect of the Invention

[0018] The present invention provides the following excellent effects. The holographic data display device according to the present invention can display three-dimensional images on a large screen by increasing the number of spatial light modulators arranged in the SLM array. Furthermore, the hologram data display device can also achieve a wider viewing area by increasing the number of spatial light modulators and applying spatial light modulators with narrow pixel pitches. Therefore, the hologram data display device can display three-dimensional images with a wide viewing area and a large screen with a compact configuration. Furthermore, the hologram data generating device is capable of generating hologram data with a compact configuration, which allows the three-dimensional image that is the basis of the subject data to be reproduced on the hologram data display device side. [Brief description of the drawings]

[0019] [Figure 1] 1 is a schematic diagram showing an overview of processing performed by a hologram data display device and a hologram data generating device according to an embodiment of the present invention. [Diagram 2] 1 is a block diagram showing an example of the configuration of a hologram data display device and a hologram data generating device according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a schematic diagram showing a processing flow of the display system according to the first embodiment. [Figure 4] FIG. 11 is a schematic diagram showing a processing flow of a display system according to a second embodiment. [Diagram 5] FIG. 11 is a schematic diagram showing a processing flow of a display system according to a third embodiment. [Figure 6] FIG. 13 is a schematic diagram showing a processing flow of a display system according to a fourth embodiment. [Figure 7] FIG. 13 is a schematic diagram showing a processing flow of a display system according to a fifth embodiment. [Figure 8] FIG. 11 is an explanatory diagram of a first simulation. [Figure 9] FIG. 11 is an explanatory diagram of a second simulation. [Figure 10] FIG. 13 is an explanatory diagram of a third simulation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, embodiments of a hologram data display device, a hologram data generating device, and a display system according to the present invention will be described in order. [Outline of the hologram data display device] As shown in FIG. 1, the hologram data display device 1 includes an SLM array 10 and a DOE (Diffractive Optical Element) 11. The SLM array 10 is a two-dimensional array of multiple SLMs (Spatial Light Modulators) 10. i and displays hologram data 3. Note that i is an identifier of the SLM, and i=1, 2, .... The hologram data 3 is data that has been created in advance by a hologram data generating device 2. In other words, the hologram data 3 is data that has been created in advance by calculation of causing object light 24 modulated by a virtual DOE (diffractive optical element) 21, which has characteristics that are inverse to those of DOE 11, to interfere with reference light 23.

[0021] The DOE 11 is disposed at a distance from the SLM array 10. The DOE 11 receives light reproduced from the hologram data 3 displayed on the SLM array 10. That is, the DOE 11 modulates the light reproduced by irradiating the SLM array 10 displaying the hologram data 3 with a reference light 23 as a reproduction illumination light 13. The DOE 11 modulates light 14 reproduced from the hologram data 3 previously generated by calculation using the DOE 21. For this purpose, a DOE 11 having desired characteristics is first prepared, and a DOE 21 having the inverse characteristics of the DOE 11 is set to generate the hologram data 3. Here, the inverse characteristics refer to optical characteristics that cancel out the positive characteristics of the DOE 11 when the optical characteristics of the DOE 11 are positive characteristics. For example, it is assumed that a certain light (L) is incident on a certain type (transmissive and phase modulation type) DOE 11 in a positive direction, and the phase distribution is modulated by the DOE 11 to emit light (M). In this case, when modulated light (M) is incident in the negative direction on a virtual DOE 21 of the same type (transmissive and phase modulation type) that has been set to inverse characteristics, ideally the phase distribution of the DOE 11 is offset and the original light (L) is emitted. Note that when the positive characteristics are expressed as a function, vector, matrix, complex number, etc., the inverse characteristics correspond to the inverse function, inverse vector, inverse matrix, complex conjugate, etc.

[0022] The SLMs constituting the SLM array 10 can be SLMs commonly used in holography. The SLM is, for example, a liquid crystal display device. When using a liquid crystal display device for the SLM, it is preferable to make the pixel pitch narrower, less than a few μm, in order to achieve a wide viewing angle. The number of SLMs in the SLM array 10 may be more than one, and is not limited to the number shown in the figure (i=1 to 4) or the arrangement shown in the figure (2 vertical × 2 horizontal).

[0023] The DOE 11 is an optical element that utilizes the diffraction phenomenon of light, and converts (modulates) incident light into a pre-designed pattern. DOE functions include a multifocal lens function and a diffusion screen function. DOEs are available in types that transmit incident light and types that reflect it. Known types of DOEs include phase modulation types and amplitude modulation types.

[0024] For example, in the case of a phase modulation type DOE, the thickness of the DOE is a concave-convex structure with thick and thin regions. Light passing through a thick region is delayed relatively compared to light passing through a non-thick region. Conversely, light passing through a thin region is not delayed relatively compared to light passing through a non-thick region. When the surface of the DOE is observed under magnification, it is found that the smallest unit region of the concave-convex structure, a region where two minimum units are connected, a region where three minimum units are connected, a region where four minimum units are connected, a region where five minimum units are connected, a region where six minimum units are connected, a region where seven minimum units are connected, etc. are arranged without any gaps so as to fill the plane. Therefore, in this embodiment, the smallest unit of the concave-convex structure of the DOE is called a pixel.

[0025] Also, for example, in the case of an amplitude modulation type DOE, the DOE passes or does not pass light depending on the area. Alternatively, an amplitude modulation type DOE modulates the input light by passing half the light or one-quarter of the light. Therefore, in this embodiment, the smallest unit of the area with different light intensity on the surface of the DOE is also called a pixel.

[0026] [Example of the configuration of a hologram data display device] 2 is a block diagram showing a display system S including a hologram data display device 1 and a hologram data generation device 2. The hologram data display device 1 shown in FIG. The light source 12 actually irradiates the SLM array 10 displaying the hologram data 3 with the reference light 23 as the reconstruction illumination light 13. The light source 12 may be an external device of the hologram data display device 1, but may also be provided inside the hologram data display device 1. The light source 12 may be a light source that is generally used in holography. The wavelength of the light source is not particularly limited, and may be visible light. The light source 12 is, for example, a laser light.

[0027] The hologram data display device 1 can include a synchronization device 17 and a control unit 18, if necessary. The synchronizer 17 outputs a synchronization signal to the SLM array 10 and the light source 12 for synchronizing, for example, the display timing of the hologram data 3 displayed on the SLM array 10 with the irradiation timing of the light source 12 .

[0028] The control unit 18 outputs operation instructions to, for example, the SLM array 10 and the light source 12. The control unit 18 can also receive the hologram data 3 from the hologram data generating device 2, store the hologram data 3, and output the hologram data 3 to the SLM array 10. The control unit 18 is realized, for example, by a general computer including a storage unit and a processing unit. The processing unit operates based on a hologram data display program stored in the storage unit. The hologram data display program is a program for causing a computer to function as the hologram data display device 1. The control unit 18 may be incorporated, for example, in a liquid crystal display device and used as an SLM that constitutes the SLM array 10.

[0029] [Outline of processing by the hologram data display device] The process performed by the hologram data display device 1 is outlined below. (Regarding placement) In FIG. 1, the DOE 11 is disposed at a position z away from the SLM array 10 in the z direction. D The position of the DOE 11 is set to the z direction with the position of the SLM array 10 as the reference (position 0). D The position of the SLM array 20 in the z direction is taken as the reference (position 0), and the position of the DOE 21 is also taken as the z D The distance from the position of the SLM array 10 to the position of the DOE 11 is z D (If we express the distance including the propagation direction, it is +z D ), and the distance from the position of the DOE 21 to the position of the SLM array 20 is z D (When expressing the distance including the propagation direction, -z D ) In addition, the position of the object light (Object Light) 25 is z O Similarly, the position of the reconstructed light 15 is z O In other words, the distance from the position of the SLM array 10 to the position of the reconstructed light 15 is z O (If we express the distance including the propagation direction, it is +z O ), and the distance from the position of the object beam 25 to the position of the SLM array 20 is z O (When expressing the distance including the propagation direction, -z O )

[0030] Here, the position of the reconstruction light 15 (and the position of the object light 25) z O can be set to a desired value depending on the depth at which the three-dimensional image 16 is to be displayed. Also, at the position of DOE21 (and the position of DOE11) z D can be set to a desired value depending on the quality of the 3D image 16 to be displayed. Note that the 3D image to be reproduced may have a reduced brightness in the area corresponding to the gap between the SLMs, resulting in brightness unevenness. However, when the DOE 21 is positioned at the z D By adjusting the position z of the DOE21, it is possible to eliminate the unevenness in brightness. D Regardless of this, it is also possible to reduce brightness unevenness by performing a process in advance to increase the brightness of areas in a 3D image where the brightness is low (such as areas corresponding to the gaps between SLMs).

[0031] As shown in Fig. 1, an SLM array 10 displays hologram data 3. The hologram data is reconstructed by irradiating the SLM array 10 on which the hologram data 3 is displayed with the reference light 23 used when generating the hologram as the reconstruction illumination light 13. The reconstructed light is guided to a predetermined distance z D By propagating the light, a reconstructed light 14 modulated by the DOE 21 applied when the hologram data was generated is obtained. The reconstructed light 14 modulated by the DOE 21 is modulated by transmitting or reflecting the DOE 11 and is distorted over a predetermined distance (z O -z D) to obtain a reconstructed light 15, and a three-dimensional image 16 is reproduced.

[0032] 1, the reference numerals of the components of the hologram data display device 1 are in the tens range, and the reference numerals of the components of the hologram data generation device 2 are in the twenties range. Furthermore, the ones digit of the reference numerals of the components of the hologram data generation device 2 that correspond to the components of the hologram data display device 1 corresponds to the ones digit of the reference numerals of the components of the hologram data display device 1. 1, the reconstructed beams 14 and 15 and the object beams 24 and 25 are shown as schematic wavefronts of light. The three-dimensional image 16 is not limited to a cylinder or a rectangular parallelepiped shown in the figure, and may be another three-dimensional shape as long as it has the same shape as the subject data 26 on which the three-dimensional image 16 is based.

[0033] [Outline of the hologram data generator] Next, an overview of the hologram data generating device 2 will be described. The hologram data generator 2 generates hologram data 3 to be displayed on the SLM array 10 of the hologram data display device 1 through calculation. The hologram data generating device 2 is realized by a general computer including a storage unit and a processing unit, such as a personal computer. For example, the hologram data generating device 2 shown in FIG. 2 includes a CPU 51, a ROM (Read Only Memory) 52, a RAM (Random Access Memory) 53, a HDD (Hard Disk Drive) 54, an input / output interface 55, a communication interface 56, and a media interface 57.

[0034] The CPU 51 operates based on a hologram data generation program stored in the ROM 52 or the HDD 54, and executes the hologram data generation program read into the RAM 53. The hologram data generation program is a program for causing a computer to function as the hologram data generation device 2. The input / output interface 55 is connected to an input device 61 such as a mouse or a keyboard, and an output device 62 such as a display. The media interface 57 writes data to and reads data from a recording medium 64 such as a semiconductor memory.

[0035] The generated hologram data can be transmitted to the hologram data display device 1 via a network 63. It is also possible to record the hologram data in advance on a recording medium 64, and read the recording medium 64 in the hologram data display device 1.

[0036] [Outline of processing by the hologram data generator] The process performed by the hologram data generating device 2 is outlined below. The calculation for generating the hologram data 3 by the hologram data generating device 2 has a complementary relationship with the hologram reproduction process. As shown in FIG. 1, the hologram data generating device 2 transmits object light 25 from object data 26 on which a three-dimensional image 16 is based to a DOE 21 (distance: z O -z D ), the object beam 24 modulated by the DOE 21 is calculated. The hologram data generating device 2 converts the object light 24 modulated by the DOE 21 into the SLM 20. i is propagated to the SLM array 20 in which multiple beams are arranged (distance: -z D ) and interfere with a reference beam 23 to calculate hologram data 3. The SLM array 20 has a similar configuration to the SLM array 10, but is not real, but is virtual. The DOE 21 has a similar configuration to the DOE 11, but is not real, but is virtual, and has optical properties opposite to those of the DOE 11.

[0037] [Effects of the hologram data display device and the hologram data generation device] In the hologram data display device 1 and hologram data generation device 2 having the configuration shown in FIG. 1, a desired reconstructed beam 15 can be obtained by designing the DOE 11 (real) and the DOE 21 (virtual). The observer observes the hologram from the side where the 3D image 16 is arranged (the right side in FIG. 1) with the DOE 11 as a reference in FIG. 1. In other words, the observer sees the 3D image 16 through the DOE 11, so that the SLM 10 i Even if the gap between the SLM10 and the DOE11 is large enough to be visible to the naked eye, it can be hidden. i Gaps will be visible, and the quality of the three-dimensional image 16 will deteriorate significantly. Furthermore, since unwanted light (higher-order diffracted light, zero-order light, etc.) is modulated by transmitting or reflecting on the DOE 11, the unwanted light can be made less noticeable to the observer than the desired reconstructed light 15.

[0038] From the perspective of recording the object light 25, all the light from an object point that constitutes the subject data 26 is recorded by the SLM 20. i When the light from a certain object point reaches a narrow region called the gap between the object points (the cross-shaped region in Fig. 1), it is not possible to record or reproduce the object point. On the other hand, by performing modulation using the DOE21, the light from the certain object point reaches the SLM20 due to the effect of this modulation. i In this case, the light beam can be incident on the SLM array 20 widely, over the gap between the SLMs (e.g., the cross-shaped area). i Since there are gaps between the recorded images, some of the hologram data 3 will be lost in the display system. However, the redundancy of holography makes it possible to reconstruct the recorded object points, albeit with some degradation due to the loss. Increasing the number of pixels in the SLM can improve the PSNR (Peak Signal to Noise Ratio) of the reconstructed image.

[0039] When the hologram data 3 generated by the hologram data generating device 2 is displayed by the hologram data display device 1, the two devices may be directly connected, or may be connected via a recording medium on which the hologram data 3 is written. Alternatively, the hologram data 3 may be transferred via broadcasting or transmission, either wired or wirelessly. In addition, each SLM 10 constituting the SLM array 10 i The SLMs do not all need to have the same specifications; for example, SLMs with different numbers of pixels or pixel pitches may be arranged. i It is not necessary for all of the specifications to be the same. Furthermore, in the hologram data display device 1, the configuration between the SLM array 10 and the DOE 11 can be, for example, free space (air). Alternatively, a light-transmitting member made of a material that transmits visible light, such as glass or resin, can be disposed between the SLM array 10 and the DOE 11 so as to integrate the SLM array 10 and the DOE 11. By integrating the SLM array 10 and the DOE 11 in this way, it is possible to prevent the positional relationship between the SLM array 10 and the DOE 11 from shifting.

[0040] The display systems according to the first to fifth embodiments will be described below in order with reference to the drawings. (First embodiment) As shown in Fig. 3, the display system according to the first embodiment includes a hologram data display device 101 and a hologram data generating device 102. In Fig. 3, the reference numerals of the components of each device are indicated by numbers in the 100 range to indicate that this is the first embodiment. The last two digits of the reference numerals of the components of each device correspond to the reference numerals of the components shown in Fig. 1. Below, explanations of the same configuration as in Fig. 1 will be omitted as appropriate.

[0041] In this embodiment, the DOE 111 constituting the hologram data display device 101 diffuses the incident light by modulating the phase of the incident light. Hereinafter, it is assumed that the DOE 111 randomly modulates the phase of the incident light. Also, the phase distribution is expressed as φ DIt is expressed as (x,y), where (x,y) represent spatial coordinates.

[0042] On the other hand, in the hologram data generation device 102, the processing unit (CPU 51) sequentially executes the following first calculation process S1, second calculation process S2, third calculation process S3, fourth calculation process S4, and fifth calculation process S5. The first calculation process S 1 is a process for generating object light 125 from subject data 126 . The second calculation process S 2 is a process for propagating the object light 125 to the DOE 121 . Here, the position z O The complex amplitude distribution of the object light 125 in O ) The propagation distance of the object light 125 to the DOE 121 is (z D -z O ) That is, the DOE 121 is at position z D The DOE 121 has the inverse characteristics of the DOE 111.

[0043] The third calculation process S3 is a process for calculating the object light 124 modulated by the DOE 121. Here, the phase distribution of the DOE 121 is expressed as φ D * (x,y), i.e. φ D The modulated object beam 124 is calculated as the phase conjugate of (x, y). Note that the complex amplitude distribution at the position of the DOE 121 is O(x, y, z D )exp[jφ D * (x, y)] can be expressed as

[0044] The fourth calculation process S4 is a process of propagating the object beam 124 modulated by the DOE 121 to the SLM array 120. Here, the propagation distance of the modulated object beam 124 to the SLM array 110 is (-z D ), and let the complex amplitude distribution of the modulated object beam 124 at the position of the SLM array 120 be O(x,y,0).

[0045] The fifth calculation process S5 is a process of causing the object beam 124 modulated by the DOE 121 to interfere with the reference beam 123 to generate the hologram data 103. Here, the complex amplitude distribution of the reference beam 123 at the position of the SLM array 120 is represented as R(x, y, 0). In addition, when generating hologram data from the interference fringes of the object light O(x,y,0) and the reference light R(x,y,0), each SLM 10 constituting the SLM array 110 of the hologram data display device 101 i Calculations are performed according to specifications such as the number of pixels, pixel pitch, and modulation method (see Figure 1). One example is the SLM10 i is a phase-modulating SLM, and the interference fringes that contribute to the reconstructed light are O(x,y,0)R * When only (x, y, 0) is considered, the hologram data 103 (phase hologram data φ H (x, y) can be expressed by the following equation (4).

[0046] φ H (x,y)=arg[O(x,y,0)R * (x, y, 0)] … Equation (4)

[0047] On the other hand, in the hologram data display device 101, hologram data 103 is displayed on the SLM array 110, and the recorded object beam is reconstructed by irradiating the SLM array 110 with the reference beam 123 that was used when the hologram data 103 was generated as the reconstruction illumination beam 113. The reconstruction illumination beam 113 is emitted from a light source 112.

[0048] According to the principle of holography, the wavefront (complex amplitude distribution) of the recorded object light is reproduced as the reconstructed light. Therefore, the reconstructed light propagates to the DOE 111 (propagation distance: z D ), the reconstructed light 114 modulated by the DOE 121 on the hologram data generation side is reproduced. The complex amplitude distribution of the reconstructed light 114 at the position of the DOE 111 is the same as the complex amplitude distribution of the object light at the position of the DOE 121 on the hologram data generation side. In other words, the complex amplitude distribution of the reconstructed light 114 is expressed as O(x, y, z D )exp[jφD * (x, y)] can be expressed as

[0049] The modulated reconstructed light 114 is transmitted through or reflected by the DOE 111 on the display side, and the phase distribution of the DOE 121 on the hologram data generation side is offset. Here, the complex amplitude distribution after the phase distribution of the DOE 121 is offset is expressed as O(x, y, z D The reconstructed light having this complex amplitude distribution can be expressed as O -z D ), the recorded object light (wavefront) 125 is reproduced as the reproduced light (wavefront) 115. This allows the hologram data display device 101 to present a three-dimensional image 116 to the observer.

[0050] In addition, although Fig. 3 illustrates the reference light 123 being irradiated perpendicularly to the hologram surface, it may be irradiated non-perpendicularly as shown in Fig. 1. Similarly, the irradiation direction of the reconstruction illumination light 113 may be either perpendicular or non-perpendicular as long as it is the same as the direction of the reference light 123.

[0051] In the display system, the case where phase hologram data is generated and reproduced has been described as an example, but it is also possible to generate and reproduce amplitude hologram (second embodiment) or complex amplitude hologram (third embodiment) data. Furthermore, when generating hologram data 103, known hologram generation processes may be applied to the hologram data generation processes other than the calculation process, except for the calculation of modulating object light using DOE 121. For example, a ray-wavefront conversion technique may be used in the first calculation process S1 for generating object light 125 from subject data 126. Furthermore, in the fifth calculation process S5 (when generating phase hologram data), the hologram data may be optimized by the Fourier iteration method or the error diffusion method. In addition, in reproducing hologram data, other than the process of modulating the reproduced light using the DOE 111, known hologram reproduction means may be applied.

[0052] Second embodiment Next, a display system according to a second embodiment will be described with reference to FIG. The display system according to the second embodiment includes a hologram data display device 201 and a hologram data generating device 202. In Fig. 4, the reference numerals of the components of each device are indicated by numbers in the 200 range to indicate that this is the second embodiment. The last two digits of the reference numerals of the components of each device correspond to the reference numerals of the components shown in Fig. 1. Below, explanations of the same configuration as in Fig. 3 will be omitted as appropriate.

[0053] In this embodiment, the DOE 211 constituting the hologram data display device 201 diffuses the incident light by modulating the amplitude of the incident light. Hereinafter, it is assumed that the DOE 211 randomly modulates the amplitude of the incident light, and the amplitude distribution is A D The explanation will be given assuming that it is represented as (x, y). Meanwhile, in the hologram data generating device 202, the processing unit (CPU 51) sequentially executes the calculation processes S1, S2, S3B, S4, and S5. That is, first, the hologram data generating device 202 generates the object light 225 based on the subject data 226, and performs a propagation calculation to the DOE 221 (S1, S2).

[0054] The next third calculation process S3B differs from the third calculation process S3 in the following points. The amplitude modulation type DOE 211 cannot physically perform negative modulation, so in principle it generates zero-order light. The zero-order light means light that is not modulated by the DOE 211. Therefore, unless some ingenuity is taken, the SLM 20 will not emit zero-order light when observing the reconstructed light 215, just as in the case where the DOE is not applied. i The gap in between is visible. In order to remove the zero-order light component when generating the hologram data 203, the hologram data generating device 202 calculates the amplitude distribution A D Instead of (x, y) itself, the average value μ D A minus D * (x, y) is modulated as the amplitude distribution of the DOE 221.

[0055] A D * (x,y)=A D (x,y)-μ D … Formula (5)

[0056] That is, the hologram data generating device 202 generates the amplitude distribution A D From (x,y), the amplitude distribution A D The average value of (x,y) μ D A minus D * The object light 224 is calculated by modulating (x, y) as the amplitude distribution of the DOE 221. D * The asterisk symbol in (x,y) does not denote a complex conjugate. Although it is physically impossible to perform negative amplitude modulation, the DOE 221 is a calculation-based virtual DOE, and therefore it is possible to perform negative amplitude modulation. Following the third calculation process S3B, the hologram data generation device 202 propagates this object beam 224 to the SLM array 220, where it interferes with the reference beam 223, and generates the hologram data 203 (S4, S5).

[0057] On the other hand, in hologram data display device 201, hologram data 203 is displayed on SLM array 210, and reference light 223 applied when generating hologram data 203 is irradiated as reconstruction illumination light 213, thereby reconstructing the recorded object light. Note that reconstruction illumination light 213 is emitted from light source 212. Thereafter, similarly to the first embodiment, the reconstructed light (reconstructed light 214 modulated by DOE 221) passes through or is reflected by DOE 211, and recorded object light 225 is reproduced as reconstruction light 215. As in the first embodiment, in generating and reproducing hologram data other than the process of modulating the object light and the reproduction light using DOE 211 and DOE 221, known hologram generating and reproducing means may be used.

[0058] Third embodiment Next, a display system according to a third embodiment will be described with reference to FIG. The display system according to the third embodiment includes a hologram data display device 301 and a hologram data generating device 302. In Fig. 5, the reference numerals of the components of each device are indicated by numbers in the 300 range to indicate that this is the third embodiment. The last two digits of the reference numerals of the components of each device correspond to the reference numerals of the components shown in Fig. 1. Below, explanations of the same configuration as in Fig. 3 will be omitted as appropriate.

[0059] In this embodiment, the DOE 311 constituting the hologram data display device 301 is a complex amplitude modulation type diffractive optical element. Below, the complex amplitude distribution of DOE311 is denoted as A D (x,y)exp[jφ D In this explanation, the vector is represented as (x, y)]. Meanwhile, in the hologram data generating device 302, the processing unit (CPU 51) sequentially executes each of the calculation processes S1, S2, S3C, S4, and S5. That is, first, the hologram data generating device 302 generates the object light 325 based on the subject data 326, and performs a propagation calculation to the DOE 321 (S1, S2).

[0060] The next third calculation process S3C differs from the third calculation process S3 in the following points. In the formula for the complex amplitude distribution, the phase component (φ D As for (x, y)), similarly to the first embodiment, the phase conjugate distribution φ D * Use (x,y). Here, the complex amplitude distribution A D (x,y)exp[jφ D (x,y)] average value μ D will be close to zero if the phase distribution is random. Therefore, the complex amplitude distribution A D (x,y)exp[jφ D (x,y)] to the average value μ DThe object beam 324 may be calculated by subtracting the above and modulating the result as the complex amplitude distribution of the DOE 321, or the subtraction may be omitted and the result may be modulated as the complex amplitude distribution of the DOE 321.

[0061] As in the first embodiment, in generating and reproducing hologram data other than the process of modulating the object light and the reproduction light using DOE 311 and DOE 321, known hologram generating and reproducing means may be used.

[0062] (Fourth embodiment) Next, a display system according to a fourth embodiment will be described with reference to FIG. The display system according to the fourth embodiment includes a hologram data display device 401 and a hologram data generating device 402. In Fig. 6, the reference numerals of the components of each device are indicated by numbers in the 400 range to indicate that this is the fourth embodiment. The last two digits of the reference numerals of the components of each device correspond to the reference numerals of the components shown in Fig. 1. Below, explanations of the same configuration as in Fig. 3 will be omitted as appropriate.

[0063] This embodiment can be applied to any of the first to third embodiments already described, as long as the wavelength of the reference light can be multi-wavelength instead of a single wavelength to generate hologram data. Hereinafter, the fourth embodiment will be described with respect to the differences from the first to third embodiments.

[0064] The hologram data generating device 402 generates hologram data by using multiple wavelengths of the reference light. j is a multi-wavelength reference light 423 obtained by time division. j Here, j is an identifier for identifying the wavelength of light. For example, when three colors of light are emitted, j may be set to 1, 2, and 3. As an example, the reference light 423 j is assumed to be light of the three colors RGB. In this case, j=R, G, B, which corresponds to the three colors RGB.

[0065] That is, the reference light 423 shown in the figure j is the first reference beam 423 R and the second reference beam 423 G and the third reference beam 423 B The hologram data 403 shown in the figure is a generalized version of the above. j The first hologram data 403 R and the second hologram data 403 G and the third hologram data 403 B Similarly, in the illustrated hologram data generating device 402, the object beam 425 j , modulated object beam 424 j , Hologram data 403 j is the reference beam 423 j The figure shows a generalized representation of the three RGB colors corresponding to the above.

[0066] On the other hand, the holographic data display device 401 includes a light source 412 in addition to the SLM array 410 and the DOE 411. j and a synchronization device 417. light source 412 j is a reconstructed illumination light 413 having multiple wavelengths by time division for the SLM array 410. j The illustrated light source 412 is switched to emit light. j is the first light source 412 R and the second light source 412 G and the third light source 412 B The first light source 412 is a generalized example of the first light source 412. R is the wavelength λ corresponding to red R The second light source 412 emits light of G is the wavelength λ corresponding to green G The third light source 412 emits light of B is the wavelength λ corresponding to blue B The light emitted is

[0067] light source 412 i can be configured by, for example, providing red light source elements, green light source elements, and blue light source elements in a predetermined periodic array. Each light source element can be, for example, a semiconductor laser. In the illustrated hologram data display device 401, the reconstructing illumination light 413 j , modulated regenerated light 414 j , regeneration light 415 j , 3D image 416 j is light source 412 j The figure shows a generalized representation of the three RGB colors corresponding to the above.

[0068] The synchronizer 417 synchronizes the reconstructed illumination light 413 j Wavelength and Hologram Data 403 j The synchronization device 417 synchronizes the switching timing between the SLM array 410 and the light source 412. j The SLM array 410 outputs a synchronization signal for each wavelength according to the time. j Switch between the two. Light source 412 j In accordance with the synchronization signal, the reconstructed illumination light 413 corresponding to each wavelength is generated according to time. j Switch and fire.

[0069] Specifically, the light source 412 j is the first wavelength λ R and a second wavelength λ G and the third wavelength λ B That is, the SLM array 410 emits light of the first wavelength λ R First hologram data 403 according to R When the light source 412 is displayed, j is the first wavelength λ R The SLM array 410 also emits light of a second wavelength λ G Second hologram data 403 according to G When the light source 412 is displayed, j is the second wavelength λ G In addition, the SLM array 410 emits light of a third wavelength λ B Third hologram data 403 according to B When the light source 412 is displayed, j is the third wavelength λ BAs a result, the hologram data display device 401 displays a color three-dimensional image 416 j can be presented to the observer.

[0070] Fifth embodiment Next, a display system according to a fifth embodiment will be described with reference to FIG. The display system according to the fifth embodiment includes a hologram data display device 501 and a hologram data generating device 502. In Fig. 7, the reference numerals of the components of each device are indicated by numbers in the 500 range to indicate that this is the fifth embodiment. The last two digits of the reference numerals of the components of each device correspond to the reference numerals of the components shown in Fig. 1. Hereinafter, explanations of the same configuration as in Fig. 6 will be omitted as appropriate.

[0071] This embodiment can be applied to any of the first to fourth embodiments described above, so long as the wavelength of the reference light is not a single wavelength but a multi-wavelength, and hologram data can be generated and displayed in a spatially divided manner. In the following, the fifth embodiment will be described with respect to the differences from the fourth embodiment.

[0072] A color filter 519 is disposed on the DOE 511 constituting the hologram data display device 501. As an example, the reference light 523 j is assumed to be light of three colors, RGB. Here, j=R, G, B, specifically corresponding to the three colors, RGB. In this case, color filters 519 of the three colors, RGB, arranged in a predetermined periodic array are arranged on the DOE 511. As the color filters, general filters made of known materials can be used. As the array method of the color filters, general methods such as the Bayer method can be used. Note that color filters can also be arranged on the SLM array 510 instead of the DOE 511.

[0073] In the following, this embodiment is applied to, for example, any one of the first to third embodiments. In this case, the hologram data generating device 502 generates a reference light 523 having multiple wavelengths by time division. jEach hologram data 503 generated by j By multiplexing the hologram data 503 k Here, the identifier k indicates that the hologram data is multiplexed. Specifically, the hologram data 503 k is the first wavelength λ R First hologram data 503 according to R and the second wavelength λ G Second hologram data 503 according to G and the third wavelength λ B Third hologram data 503 according to B and are multiplexed.

[0074] The illustrated reference beam 523 j is the first reference beam 523 R and the second reference beam 523 G and the third reference beam 523 B Similarly, in the illustrated hologram data generating device 502, the object light 525 j , modulated object beam 524 j is the reference beam 423 j The figure shows a generalized representation of the three RGB colors corresponding to the above.

[0075] On the other hand, in the hologram data display device 501, a light source 512 of three colors of RGB is k is the multiplexed hologram data 503 k Based on this premise, the SLM array 510 is multiplexed with RGB three-color reconstructed illumination light 513 k In the illustrated hologram data display device 501, modulated reconstructed light 514 is irradiated. k shows the multiplexed RGB tricolors. Modulated regenerated light 514 k is spatially divided into a first wavelength λ by a color filter 519 disposed in the DOE 511. R and a second wavelength λ G and the third wavelength λ B It should be noted that the reconstructed light 514 shown in the figure can be separated into the reconstructed light 514. j and 3D images 516j shows a generalized spatially divided RGB triplet. In addition, since this embodiment does not require a synchronization device, the hologram data display device can be constructed in a compact configuration.

[0076] The hologram data display device, hologram data generation device, and display system according to the embodiments of the present invention have been described above, but the scope of the present invention is not limited to these descriptions and should be broadly interpreted based on the claims. Furthermore, it goes without saying that various changes and modifications based on these descriptions are also included in the scope of the present invention.

[0077] Below, we will explain in turn some simulations that were performed to verify the effects of the display system. [Simulation 1] A simulation for verifying generation and reproduction of hologram data in the display system according to the first embodiment will be described with reference to FIG. 3 (and also with reference to FIG. 8 where necessary). The simulation conditions are as follows. (SLM Array 110) The number of pixels of the SLMs constituting the SLM array 110: 3596 pixels horizontally × 8192 pixels vertically Arrangement of SLMs constituting the SLM array 110: 2 horizontally × 1 vertically SLM pixel pitch: p = 2 μm SLM modulation method: Phase modulation type SLM gray scale: 256 values ​​(8 bits) Gap between SLMs: g = 2 mm Position of SLM array 110: 0 mm (DOE111) Number of pixels in DOE: 16384 pixels horizontally x 16384 pixels vertically DOE pixel pitch: 2μm DOE modulation method: Phase modulation type DOE gray scale: 2 levels (1 bit) DOE modulation pattern: phase random pattern Position of DOE111: z D =51.13mm (DOE121) Calculations were performed under the same conditions as DOE111 (but with inverse characteristics). (Subject data 126) Input image pixel count: 256 pixels x 256 pixels Pixel pitch of input image: 32 μm (pixel aperture: 2 μm) (Object light 125) It was generated by giving a random phase to each pixel of the input image. Wavelength of object light 125: 632.8 nm Position of object beam 125: z O =5mm The wavelength of the reference light is also 632.8 nm.

[0078] The results of generating hologram data 103 and performing reconstruction calculations under the above conditions are set as Example 1. For comparison, the results of generating hologram data and performing reconstruction calculations under conditions other than the above DOE conditions (without DOE) are set as Comparative Example 1. Fig. 8(a) is a diagram showing a schematic arrangement of the SLM array 110 and the DOE 111 in Simulation 1. Fig. 8(b) is a diagram showing the reconstruction result of Comparative Example 1 (when there is no DOE). Fig. 8(c) is a diagram showing the reconstruction result of Example 1 (when there is a DOE). Fig. 8(d) is a reference diagram showing the input image (subject data 126). According to the reproduction results of Comparative Example 1, when DOE111 and DOE121 are not applied, the gap between the SLMs is clearly observed, and it is found that the image quality is deteriorated. On the other hand, according to the reproduction results of Example 1, it was confirmed that a 3D image in which the gap between the SLMs is hidden can be obtained with a compact configuration without using a large optical system as in the conventional technology by applying DOE111 and DOE121. Also, according to Example 1, by increasing the number of SLMs and applying SLMs with a narrow pixel pitch, it is possible to display a 3D image with a wide viewing area and a large screen.

[0079] [Simulation 2] Next, a simulation for verifying generation and reproduction of hologram data in the display system according to the second embodiment will be described with reference to FIG. 4 (and also with reference to FIG. 9 where appropriate). The only difference between the simulation conditions of Simulation 2 and Simulation 1 is that DOE211 and DOE221 in Simulation 2 are amplitude modulation types. All other parameters were the same as those in Simulation 1.

[0080] The results of generating hologram data 203 and performing reconstruction calculations under the above conditions are shown in Example 2. For comparison, the amplitude distribution A D (x,y) to average value μ D The results of generating hologram data and performing reconstruction calculations without subtracting the average value μ D A minus D * By modulating (x, y) (see equation (5) above) as the amplitude distribution of the DOE 221, the object light 224 is calculated, and the hologram data 203 is generated and a reconstruction calculation is performed.

[0081] FIG. 9(a) is a diagram showing a schematic arrangement of the SLM array 210 and the DOE 211 in Simulation 2. FIG. 9(b) is a diagram showing Comparative Example 2 (average value μ D FIG. 9(c) shows the reproduction results of Example 2 (without subtraction of the average value μ D 9(d) is a reference diagram showing the input image (subject data 126).

[0082] According to the reproduction results of Comparative Example 2, the amplitude distribution A D (x,y) to average value μ D When not subtracted, the inter-SLM gap is clearly observed, and the image quality is degraded. On the other hand, according to the reproduction results of Example 2, the amplitude distribution A D (x,y) to average value μ DIt was confirmed that by subtracting the , a 3D image with the gap between the SLMs hidden can be obtained with a compact configuration. Also, according to the second embodiment, by increasing the number of SLMs and applying SLMs with narrow pixel pitches, a 3D image can be displayed with a wide viewing area and a large screen.

[0083] [Simulation 3] Next, in the display system, the DOE position z D A simulation for verifying the relationship between the image quality of the reproduced 3D video and the input video signal will be described with reference to FIG. 1 (and FIG. 10 as appropriate). The simulation conditions in this case are as follows: (SLM Array 10) The number of pixels of the SLMs constituting the SLM array 10: 1792 pixels horizontally × 952 pixels vertically Arrangement of SLMs constituting the SLM array 10: 2 horizontal × 2 vertical SLM pixel pitch: p = 3.74 μm SLM modulation method: Phase modulation type SLM gray scale: 256 values ​​(8 bits) Gap between SLMs: g = 0.957 mm Position of SLM array 10: 0 mm (DOE11) Number of pixels in DOE: 8192 pixels horizontally x 8192 pixels vertically DOE pixel pitch: 3.74μm DOE modulation method: Phase modulation type DOE gray scale: 256 values ​​(8 bits) DOE modulation pattern: phase random pattern Position of DOE11: z D =53.71mm (DOE21) Calculations were performed under the same conditions as DOE11 (but with inverse characteristics). (Subject data 26) Input image pixel count: 256 pixels x 256 pixels Input image pixel pitch: 29.92 μm (pixel aperture: 3.74 μm) (object light 25) It was generated by giving a random phase to each pixel of the input image. Wavelength of object beam 25: 532 nm Position of object beam 25: z O =0mm The wavelength of the reference light is also 532 nm.

[0084] Position of DOE21 (and position of DOE11) z D is SLM20 i The pixel pitch p of SLM20 i Gap length g between the SLM20 i Diffraction angle θ due to pixel structure D And, the position z of DOE21 is determined by D The position z defined by the following equation (6) D0 Using this as an index, hologram data generation and reconstruction calculations were performed under conditions changed to 0.2, 0.4, 0.6, 0.8, 1.0, and 1.2 times the index.

[0085] z D0 =[max(W,H)+g] / (2tanθ D ) … Formula (6) Where θ D =sin -1 [λ / (2p)] … Equation (7)

[0086] In formula (6), max(W,H) is a function that returns the larger value of W and H. W and H are the SLM20 i are the width W and height H of the SLM20 as shown in (2) and (3) above, respectively. i The number of pixels in the width direction of x , the number of pixels in the height direction N y 2, SLM20 i This indicates the value multiplied by the pixel pitch p.

[0087] Under these conditions, at position z of DOE21 D The change in the reproduced 3D image with respect to the position z defined by equation (6) is shown in FIG. D0The reproduction results obtained at 0.2, 0.4, 0.6, and 0.8 times the index show uneven brightness. D0 The reproduction results obtained at 1.0 and 1.2 times the index showed no unevenness in brightness. D <z D0 When z is 1, the brightness distribution of the reproduced 3D image becomes non-uniform, resulting in degradation of image quality. D ≧z D0 In this case, the object beam 24 modulated by the DOE 21 is i The light is then irradiated onto the SLM array 20 through the gap between the SLMs. i It can be seen that the gap between the DOEs is effectively hidden. Therefore, the position of DOE21 (and the position of DOE11) z D It can be concluded that it is desirable to satisfy the relationship of the following equation (8).

[0088] z D ≧[max(W,H)+g] / (2tanθ D ) … Formula (8)

[0089] Therefore, according to Simulation 3, the DOE should be placed at the appropriate position z D By arranging the projector in this way, it is no longer necessary to use a large optical system as in conventional technology, and the compact configuration can improve the quality of the reproduced 3D images. Note that formula (8) is not limited to the case where the number of SLMs is 2 horizontally and 2 vertically, but can also be applied when a greater number of SLMs are arranged. For example, a simulation was performed with 4 horizontally and 4 vertically, and it was confirmed that the formula worked correctly. [Explanation of symbols]

[0090] S Display System 1,101,201,301,401,501 Holographic data display device 2,102,202,302,402,502 Hologram data generator 3,103,203,303,403 j ,503j ,503 k Hologram Data 10 i SLM (Spatial Light Modulator) 10,110,210,310,410,510 SLM array 11,111,211,311,411,511 DOE (diffractive optical element) 12,112,212,312,412 j ,512 j ,512 k light source 13,113,213,313,413 j ,513 j ,513 k Regenerative lighting 14,114,214,314,414 j ,514 j ,514 k Modulated reconstructed light 15,115,215,315,415 j ,515 j play light 16,116,216,316,416 j ,516 j 3D images 17,417,517 Synchronous device 18 Control Unit 20 i SLM (Virtual Spatial Light Modulator) 20,120,220,320,420,520 SLM array (virtual SLM array) 21,121,221,321,421,521 DOE (Virtual Diffractive Optical Element) 23,123,223,323,423 j ,523 j reference light 24,124,224,324,424 j ,524 j Modulated object beam 25,125,225,325,425 j ,525 j object light 26,126,226,326,426 j ,526 jSubject data

Claims

1. an SLM array having a plurality of spatial light modulators arranged two-dimensionally to display holographic data; a diffractive optical element disposed at a distance from the SLM array, on which light reproduced from hologram data displayed on the SLM array is incident; A hologram data display device characterized in that the hologram data is data generated in advance by calculating an interference between an object light modulated by a virtual diffractive optical element having characteristics opposite to those of the diffractive optical element and a reference light.

2. 2. The hologram data display device according to claim 1, wherein the diffractive optical element diffuses the incident light by modulating the phase of the incident light.

3. 2. The hologram data display device according to claim 1, wherein the diffractive optical element diffuses the incident light by modulating the amplitude of the incident light.

4. 2. The hologram data display device according to claim 1, wherein the diffractive optical element is a complex amplitude modulation type diffractive optical element.

5. the hologram data is generated by a reference light having multiple wavelengths in a time division manner, a light source that switches and irradiates the SLM array with a multi-wavelength reproduction illumination light in a time division manner; 2. The hologram data display device according to claim 1, further comprising a synchronization device for synchronizing a switching timing between the wavelength of the reconstructing illumination light and the hologram data.

6. the hologram data is generated by a reference light having multiple wavelengths in a time division manner, 2. The hologram data display device according to claim 1, wherein a color filter is disposed on the diffractive optical element or the SLM array.

7. A hologram data generating device for generating hologram data to be displayed on an SLM array of a hologram data display device having an SLM array having a plurality of spatial light modulators arranged two-dimensionally and a diffractive optical element disposed at a distance from the SLM array, comprising: The apparatus includes a storage unit and a processing unit, A first calculation process for generating an object light from the subject data; a second calculation process for propagating the object light to a virtual diffractive optical element; a third calculation process for calculating an object beam modulated by the virtual diffractive optical element; a fourth calculation process of propagating the object light modulated by the virtual diffractive optical element to a virtual SLM array having a plurality of virtual spatial light modulators arranged two-dimensionally; A fifth calculation process is executed to generate hologram data by causing the object light modulated by the virtual diffractive optical element to interfere with a reference light; A hologram data generating device, wherein the virtual diffractive optical element has an inverse characteristic of the diffractive optical element.

8. A hologram data display program for causing a computer to function as the hologram data display device according to any one of claims 1 to 6.

9. A hologram data generating program for causing a computer to function as the hologram data generating device according to claim 7.

10. A hologram data display device according to any one of claims 1 to 6, A display system comprising: the hologram data generating device according to claim 7 .

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