Holographic projector device and control method

Abstract

A holographic projector device according to the present technology comprises: a light source; a spatial light modulation unit that performs spatial light modulation on light emitted from the light source; a projection unit that projects a reproduced image generated by the spatial light modulation unit; and a control unit that calculates a correction hologram for correcting deterioration in the reproduced image on the basis of a target image and deterioration element information indicating at least a resolution deterioration element of the reproduced image generated in a projection path from the light source to the projection unit, and performs control so that the spatial light modulation unit is driven according to a spatial light modulation pattern based on the calculated correction hologram.

Description

Holographic projector device and control method

[0001] The present technology relates to a holographic projector device that projects an image using holography technology and a control method thereof, and in particular to a technology for correcting degradation in resolution of a reproduced image.

[0002] Holographic projector devices that use holography technology to project images are known. Holography technology makes it possible to display 2D (two-dimensional) images and 3D (three-dimensional) images. Some holographic projector devices are configured to form holograms using a spatial light modulator, such as a liquid crystal panel. In this case, the hologram formed can be changed by changing the spatial light modulation pattern in the spatial light modulator, thereby enabling the display image to be changed. In other words, changing the spatial light modulation pattern in the spatial light modulator makes it possible to switch between still images and display moving images.

[0003] As a related prior art, the following Patent Document 1 can be cited: Patent Document 1 discloses a technique for increasing the resolution of a hologram image at a user's gaze point.

[0004] Japanese Patent Application Publication No. 10-326071

[0005] In a holographic projector device, resolution degradation of the reproduced image can occur along the projection path for projecting the reproduced image. However, in conventional holographic projector devices, no technology has been established for correcting such resolution degradation along the projection path. For example, it may be possible to use a high-resolution spatial light modulator in anticipation of resolution degradation, but in that case, the spatial light modulator to be used would be expensive, making it difficult to reduce the price.

[0006] The present technology has been made in view of the above circumstances, and aims to suppress degradation of resolution in a holographic projector device while reducing the cost.

[0007] A holographic projector device according to the present technology includes a light source, a spatial light modulation unit that performs spatial light modulation on light emitted from the light source, a projection unit that projects a reconstructed image generated by the spatial light modulation unit, and a control unit that calculates a correction hologram for correcting degradation of the reconstructed image based on a target image and degradation factor information that indicates at least a resolution degradation factor of the reconstructed image that occurs along a projection path from the light source to the projection unit, and controls the spatial light modulation unit to be driven with a spatial light modulation pattern based on the calculated correction hologram. This configuration enables resolution degradation correction that takes into account resolution degradation factors that actually occur along the projection path, thereby enabling appropriate resolution degradation correction. Furthermore, performing resolution degradation correction enables the use of a spatial light modulator with a low resolution.

[0008] 1 is a diagram showing an example of the configuration of a holographic projector device according to a first embodiment of the present technology; FIG. 2 is an explanatory diagram illustrating the principle of hologram formation by spatial light phase modulation; FIG. 3 is an explanatory diagram illustrating measures against disclination; FIG. 4 is an explanatory diagram illustrating various functions for realizing a degradation correction method according to a first embodiment; FIG. 5 is an explanatory diagram illustrating an example of shift multiplexed display; FIG. 6 is a flowchart showing an example of specific processing steps to be executed to realize the degradation correction method according to the first embodiment; FIG. 7 is an explanatory diagram illustrating the principle of hologram formation by spatial light amplitude modulation; FIG. 8 is an explanatory diagram illustrating an example of a holographic projector device according to a second embodiment; FIG. 9 is an explanatory diagram illustrating a degradation correction method according to the third embodiment; FIG. 10 is an explanatory diagram illustrating various functions for realizing the degradation correction method according to the third embodiment; FIG. 11 is a flowchart showing an example of specific processing steps to be executed to realize the degradation correction method according to the third embodiment; FIG. 12 is an explanatory diagram illustrating problems when the reproduction surface is uneven; FIG. 13 is an explanatory diagram illustrating a case where a correction hologram is calculated assuming a reproduction surface having unevenness; and FIG. 14 is an explanatory diagram of a holographic projector device according to a modified example.

[0009] Hereinafter, with reference to the accompanying drawings, embodiments according to the present technology will be described in the following order: <1. First embodiment> [1-1. Device configuration example] [1-2. Deterioration correction method as first embodiment] [1-3. Processing procedure] <2. Second embodiment> <3. Third embodiment> <4. Modified example> <5. Summary of embodiments> <6. Present technology>

[0010] 1 is a diagram showing an example of the configuration of a holographic projector device 1 according to a first embodiment of the present technology. Here, as an example, a holographic projector device that displays 2D (two-dimensional) images is shown.

[0011] As shown in the figure, the holographic projector device 1 includes a light source 2, a beam expander 3, a collimator lens 4, a beam splitter 5, a spatial light modulation unit 6, a relay lens 7, a relay lens 8, an optical filter 9, a projection lens 10, a control unit 11, and a drive unit 12.

[0012] The light source 2 is provided as a light source for generating a reconstructed image. In a holographic projector device, it is desirable to use a coherent light source as the light source for the reconstructed image, and in this example, a semiconductor laser is used as the light source 2.

[0013] Light emitted from the light source 2 is converted into diffused light by the beam expander 3, then converted into parallel light by the collimator lens 4, and enters the beam splitter 5. The light thus entering the beam splitter 5 from the light source 2 side is reflected by the selective reflection surface of the beam splitter 5, and enters the spatial light modulation unit 6 as shown in the figure.

[0014] The spatial light modulation unit 6 has a spatial light modulator, which performs spatial light modulation on incident light. This spatial light modulation is for holographic projection, and a reproduced image for realizing image display is generated by the spatial light modulation. In this embodiment, the spatial light modulator in the spatial light modulation unit 6 is a spatial light phase modulator (hereinafter sometimes abbreviated as a "phase modulator") that performs spatial light phase modulation on incident light. Specifically, a liquid crystal panel is used as the phase modulator. The liquid crystal panel is configured with a plurality of pixels, the orientation state of which is adjustable, arranged two-dimensionally, and is capable of performing spatial light phase modulation on incident light independently for each pixel. In this example, for example, LCOS (Liquid Crystal on Silicon) is used as the liquid crystal panel.

[0015] In this example, the spatial light modulation unit 6 has a reflective spatial light modulator as the spatial light modulator, and therefore, light that has been spatially modulated (spatial light phase modulated) by the spatial light modulation unit 6 is emitted from the spatial light modulation unit 6 as reflected light from the reflective spatial light modulator (a reflective liquid crystal panel in this example).

[0016] The light emitted from the spatial light modulation unit 6 after spatial light modulation is incident again on the selective reflection surface of the beam splitter 5, passes through the selective reflection surface, and enters a relay lens system composed of a relay lens 7 and a relay lens 8.

[0017] In addition, by using, for example, a polarizing beam splitter as the beam splitter 5, it is possible to reduce the light loss associated with the reflection of incident light from the light source 2 side and the transmission of incident light from the spatial light modulation unit 6, thereby increasing the light utilization efficiency.

[0018] As shown in the figure, the light incident on the relay lens 7 is converted from parallel light to convergent light, and after being focused at a predetermined position, it is incident as diffused light on the relay lens 8. The relay lens 8 converts the incident diffused light into parallel light and emits it to the projection lens 10.

[0019] An optical filter 9 is disposed between the relay lenses 7 and 8. The optical filter 9 transmits first-order diffracted light at the position where the light emitted from the relay lens 7 is focused, and blocks other light (zeroth-order diffracted light, higher-order diffracted light, etc.), thereby removing noise light.

[0020] The projection lens 10 enlarges and projects the reproduced image incident via the relay lens 8 onto a projection object such as a screen S. This makes it possible to display a 2D image on the projection object such as the screen S.

[0021] The control unit 11 is configured as a computer device equipped with a microcomputer having, for example, a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc., and executes various processes related to image display in the holographic projector device 1.

[0022] The driving unit 12 is configured to have a driving circuit for driving the spatial light modulator (a phase modulator in this example) included in the spatial light modulation unit 6. The driving unit 12 is configured to be able to individually drive each pixel of the spatial light modulator included in the spatial light modulation unit 6.

[0023] As shown in the figure, a target image (a 2D image in this example) that is a display target is input to the control unit 11. The control unit 11 controls the drive unit 12 based on this target image, thereby causing the spatial light modulation unit 6 to perform spatial light modulation for image display. Specifically, the control unit 11 calculates a hologram (CGH: Computer Generated Hologram) based on the target image to obtain a reproduced image corresponding to the target image. The control unit 11 then calculates a spatial light modulation pattern for the spatial light modulation unit 6 so that the calculated hologram is formed by spatial light modulation by the spatial light modulation unit 6, and controls the drive unit 12 to perform spatial light modulation in accordance with the spatial light modulation pattern. Here, the "spatial light modulation pattern" refers to information indicating the light modulation mode for each pixel of the spatial light modulation unit 6 (spatial light modulator). Specifically, in this example, the information indicates the drive signal value for each pixel of the spatial light modulation unit 6.

[0024] As described above, the control unit 11 controls the spatial light modulation pattern of the spatial light modulation unit 6 based on the target image, thereby realizing the display of a 2D image that reproduces the target image.

[0025] The principle of hologram formation by spatial light phase modulation will be explained with reference to Figure 2. For the sake of explanation, a case where a transmissive modulator is used as the phase modulator in the spatial light modulation unit 6 is shown here, but the principle is the same when a reflective modulator is used.

[0026] The figure shows an example in which the spatial light modulation unit 6 includes pixels that modulate the phase of incident light to a phase of 0 [rad] and pixels that modulate the phase to a phase of π [rad]. By performing spatial light phase modulation that imparts a phase distribution to incident light in this way, spherical waves of different phases interfere with each other, and the interference generates a certain pattern of light reinforcement. In other words, an interference fringe (hologram) with a certain pattern is formed. At this time, the hologram pattern can be controlled by the phase distribution pattern imparted to the incident light by the phase modulator, i.e., the spatial light modulation pattern of the phase modulator.

[0027] [1-2. Degradation Correction Method as First Embodiment] It has been confirmed that in a holographic projector device, resolution degradation of the reconstructed image occurs along the projection path for projecting the reconstructed image. In particular, when noise light is removed using an optical filter 9, as in the holographic projector device 1 described above, resolution degradation of the reconstructed image is likely to occur. Specifically, when noise light is removed in real space, a method is adopted in which the noise light is separated while narrowing the area of ​​the original reconstructed image, resulting in an image display with a resolution lower than the resolution that can be displayed, resulting in resolution degradation. Furthermore, when a filter is used in the spatial frequency domain, the angular resolution contributing to the reconstructed image is limited, resulting in resolution degradation of the reconstructed image.

[0028] Furthermore, when a liquid crystal panel is used as a spatial light modulator, resolution degradation of the reproduced image occurs due to measures taken to address disclination in the liquid crystal panel. Specifically, when a liquid crystal panel is used as a spatial light modulator, in order to suppress degradation of display image quality due to disclination, a spatial light modulator with a large pixel pitch is used, or a measure is taken in which, instead of writing information independently on a pixel-by-pixel basis (denoted as "Px" in the figure) as shown in FIG. 3A, the same information is written to multiple adjacent pixels (2 × 2 = 4 pixels or more) as shown in FIG. 3B, thereby artificially increasing the pixel pitch. Increasing the pixel pitch, as in the former case, increases the panel size, which reduces the number of pixels produced during production and leads to issues such as increased costs. Therefore, it is difficult to increase the panel size. As a result, the number of pixels in the liquid crystal panel decreases, resulting in degradation of the resolution of the reproduced image. Increasing the pixel pitch artificially, as in the latter case, reduces the effective number of pixels, resulting in degradation of the resolution of the reproduced image.

[0029] Therefore, in this embodiment, a method is adopted in which degradation correction of the reproduced image is performed using degradation element information, which is information indicating at least resolution degradation elements of the reproduced image that occur along the projection path from the light source 2 to the projection unit (at least the portion including the projection lens 10). In this embodiment, the process for this degradation correction is executed by the control unit 11.

[0030] Various functions of the control unit 11 for realizing the degradation correction method according to the first embodiment will be described with reference to Fig. 4. Fig. 4 also shows the driving unit 12 shown in Fig. 1 together with the functional blocks of the control unit 11.

[0031] In this embodiment, the control unit 11 calculates a correction hologram for correcting the degradation of the reproduced image based on the target image and the degradation element information described above, and controls the spatial light modulation unit 6 so that it is driven by a spatial light modulation pattern based on the calculated correction hologram. To this end, the control unit 11 in this embodiment has the functions of a degraded image estimation unit F1, a multiplexing image generation unit F2, a correction hologram generation unit F3, a modulation pattern generation unit F4, and an output control unit F5 shown in the figure.

[0032] In this embodiment, a method of shift-multiplexed display of multiple reconstructed images is adopted to correct resolution degradation. Here, the term "shift-multiplexed display" as used herein refers to a display method in which multiple reconstructed images are superimposed on one another on the reconstruction plane, and involves a shift (displacement) in the display positions of the reconstructed images by less than the pixel pitch. By performing this type of shift-multiplexed display, a high-resolution image display can be achieved using low-resolution reconstructed images. In other words, resolution degradation correction based on so-called super-resolution technology can be achieved.

[0033] An example of shift multiplexed display in this embodiment will be described with reference to FIG. 5 . FIG. 5A schematically illustrates multiple reconstructed images used for resolution degradation correction. As illustrated in FIG. 5A , in this embodiment, four reconstructed images are generated as the reconstructed images used for resolution degradation correction. Then, as illustrated in FIG. 5B , these four reconstructed images are superimposed on the reconstruction surface, with a shift of less than the pixel pitch occurring in the image formation areas between each reconstructed image. Specifically, in this embodiment, a shift of half a pixel occurs. As illustrated, using the image formation area of ​​one of the four reconstructed images as a reference, the remaining reconstructed image is shifted by half a pixel in the horizontal direction (see the reconstructed image marked with a black triangle in the figure), the other remaining reconstructed image is shifted by half a pixel in the vertical direction (see the reconstructed image marked with a black square in the figure), and yet another remaining reconstructed image is shifted by half a pixel in the diagonal direction (see the reconstructed image marked with an x ​​in the figure). This results in a shift of half a pixel occurring in the image formation areas between each reconstructed image.

[0034] In this embodiment, shift multiplexed display is achieved by projecting the four reconstructed images described above in a time-division manner. Specifically, in this embodiment, the control unit 11 calculates multiple correction holograms for the shift multiplexed display and controls the spatial light modulation unit 6 so that these correction holograms are formed in a time-division manner. By forming multiple correction holograms for the shift multiplexed display in this manner in a time-division manner, it becomes possible to achieve a shift of the reconstructed image for the shift multiplexed display using these correction holograms. Because the shift of the reconstructed image is achieved by the time-division formation of the correction holograms, it is not necessary to provide a shift device for shifting the position of the reconstructed image on the reconstruction plane when achieving shift multiplexed display.

[0035] For confirmation, in order to make the formation areas of each reconstructed image different on the reconstruction surface as shown in Figure 5B, it is sufficient to change the setting of which area on the reconstruction surface is to be used as the target formation area for the reconstructed image in the calculation of each correction hologram.

[0036] In FIG. 4, the functions from the degraded image estimation unit F1 to the correction hologram generation unit F3 are functions for generating a plurality of correction holograms to achieve the resolution degradation correction by the shift multiplexed display as described above.

[0037] The degraded image estimation unit F1 estimates a degraded image as an image in which the target image has been given the degradation indicated by the degradation element information, based on the target image and the degradation element information. Specifically, the process is as follows: first, a hologram reproducing the target image is calculated as an undegraded hologram, then a degraded hologram is calculated based on the undegraded hologram and the degradation element information, and then an image reproduced by the degraded hologram is calculated as the degraded image.

[0038] The undegraded hologram can be obtained by, for example, wavefront propagation calculation using the angular spectrum method. Specifically, it can be calculated as "Hologram" shown in the following [Equation 1]. In [Equation 1], "F" is the Fourier transform, "F －１ " is the inverse Fourier transform, "f ｘ " "fｙ ” are the coordinates in the frequency domain, “u １ " denotes the target wavefront, and "λ" denotes the wavelength of light.

[0039] In this embodiment, the degradation of the reproduced image is corrected by correcting the degradation of resolution caused by the optical filter 9 and the degradation occurring in the liquid crystal panel of the spatial light modulation unit 6, specifically the degradation of the reproduced image caused by the disclination described above. Furthermore, in this example, the degradation caused by optical aberration occurring in the reproduced image is also corrected. The optical aberration here can be, for example, lens distortion occurring in the projection lens 10.

[0040] In this example, the degraded image is generated by reproducing the degradation of resolution caused by the optical filter 9, the degradation of the reconstructed image caused by disclination, and the degradation of the reconstructed image caused by optical aberration. Therefore, as the degradation element information, information on the degradation elements of resolution caused by the optical filter 9, information on the degradation elements of the reconstructed image caused by disclination, and information on the degradation elements of the reconstructed image caused by optical aberration are prepared. Note that it is conceivable that the information indicating the various degradation elements may be obtained in advance experimentally or by simulation calculation.

[0041] First, a degraded hologram is calculated based on the undegraded hologram and the degradation element information. In this example, the degraded hologram is calculated using information on resolution degradation elements caused by the optical filter 9, information on degradation elements of the reconstructed image caused by disclinations, and information on degradation elements of the reconstructed image caused by optical aberrations, all of which are prepared in advance as degradation element information, so that degradation due to these degradation elements is imparted to the undegraded hologram.

[0042] Specifically, the calculation of the degradation caused by the disclination can be performed as a calculation to obtain "Hologram_Dl" in the following [Equation 2]. In [Equation 2], "A" and "φ" represent the amplitude hologram and phase hologram of the pre-degradation hologram as a complex amplitude hologram obtained by the calculation of [Equation 1]. Furthermore, "d" represents the bandwidth limitation of the display pattern caused by disclination. This information about "d" corresponds to information about the degradation factors of the reconstructed image due to disclination.

[0043] Furthermore, the calculation for imparting the degradation in resolution by the optical filter 9 can be performed as a calculation for obtaining "Hologram_Df" in the following [Equation 3]. In [Equation 3], "Mask" represents the band limit of the hologram in frequency space. Note that for "A" and "φ" in [Equation 3], the amplitude hologram and phase hologram in the complex amplitude hologram calculated as "Hologram_Dl" using [Equation 2] are used. The information on "Mask" in [Equation 3] corresponds to information on the resolution degradation factors caused by the optical filter 9.

[0044] Furthermore, in this example, a calculation is performed to further add degradation of the reconstructed image due to optical aberration to the complex amplitude hologram as "Hologram_Df" obtained by [Equation 3]. This calculation can be performed in a similar manner to [Equation 2] and [Equation 3] using information on degradation factors of the reconstructed image due to optical aberration that has been prepared in advance, such as information indicating degradation factors as lens distortion occurring in the projection lens 10.

[0045] In this example, a hologram obtained by adding various types of degradation indicated by the degradation element information to an undegraded hologram as described above is calculated as a degraded hologram. The degraded image estimation unit F1 calculates the reconstructed image from this degraded hologram as a degraded image. The degraded image can be found by performing a wavefront propagation calculation on the degraded hologram in the same manner as in [Equation 1].

[0046] It should be noted that the order in which the degradation of the resolution caused by the optical filter 9, the degradation of the reproduced image caused by disclination, and the degradation of the reproduced image caused by optical aberration is inflicted is not limited to the above order, and it is also possible to adopt other orders, such as inflicting degradation of the reproduced image caused by optical aberration → inflicting degradation of the resolution caused by the optical filter 9 → inflicting degradation of the reproduced image caused by disclination.

[0047] Here, the degradation element information, specifically, in this example, information on resolution degradation elements caused by the optical filter 9, information on degradation elements of the reproduced image caused by disclinations, and information on degradation elements of the reproduced image caused by optical aberrations, is stored in a memory (non-volatile memory) that can be read by the control unit 11. The memory may be provided within the holographic projector device 1. Alternatively, the memory may be provided in an external device (for example, a cloud server, etc.).

[0048] The multiplexing image generation unit F2 generates multiple (four in this example) multiplexing images to be used in the shift multiplexing display described above, based on the difference between the degraded image obtained by the degraded image estimation unit F1 and the target image. Specifically, the multiplexing image generation unit F2 calculates four images (with the same resolution as the target image) that can cancel the difference between the degraded image and the target image by performing the shift multiplexing display described in FIG. 5 . Note that a calculation method used in general super-resolution technology can be used to calculate the multiple multiplexing images to be used in the shift multiplexing display for correcting resolution degradation based on the difference between the degraded image and the target image. For example, the method disclosed in the following reference 1 can be used. Reference 1: “Image Enhancement in Projectors via Optical Pixel Shift and Overlay” by Behzad Sajadi, Duy Qoc-Lai, Alex T. Ihler, M. Gopi, and Aditi Majumder, Department of Computer Science, University of California, Irvine

[0049] The correction hologram generation unit F3 generates, by calculation, a hologram for obtaining the multiplexing image as a reproduced image for each multiplexing image calculated by the multiplexing image generation unit F2. The conversion from the multiplexing image to the correction hologram can also be performed by wavefront propagation calculation as shown in the above-mentioned [Equation 1], as in the conversion from the target image to the undegraded hologram described above.

[0050] The modulation pattern generation unit F4 generates, by calculation, a spatial light modulation pattern for the spatial light modulation unit 6 to form each correction hologram obtained by the correction hologram generation unit F3. In this embodiment, spatial light phase modulation is performed as the spatial light modulation, so only a phase hologram is extracted from the correction holograms as complex amplitude holograms. Specifically, the correction hologram is calculated based on "u" shown in the following [Equation 4]. ２ (x', y')" in [Equation 4]. ｉφ（ｘ’，ｙ’） " is extracted to obtain phase distribution information on the phase modulation surface of the spatial light modulation unit 6.

[0051] The modulation pattern generation unit F4 obtains the phase distribution information for each correction hologram as described above, and then calculates, for each correction hologram, drive signal values ​​for each pixel of the phase modulator to realize the phase distribution indicated by the phase distribution information on the phase modulation plane. The drive signal values ​​for each pixel of the phase modulator calculated in this way for each correction hologram are information on the spatial light modulation pattern for each correction hologram.

[0052] The output control unit F5 outputs information on the spatial light modulation pattern for each correction hologram generated by the modulation pattern generation unit F4 to the drive unit 12 in a time-division manner. This drives the phase modulator of the spatial light modulation unit 6 to form four correction holograms for shift multiplexed display in a time-division manner. As a result, reconstructed images corresponding to the four multiplexed images for correcting various degradations such as resolution are displayed in a time-division shift multiplexed manner, thereby achieving correction of various degradations in the displayed image.

[0053] For confirmation, when shift multiplexing display is performed in a time-division manner as in this embodiment, the display cycle of the multiplexing images is set to a sufficiently fast cycle taking into consideration the integral effect of vision.

[0054] In this embodiment, a phase modulator is used as the spatial light modulator for holographic projection, which can improve the light utilization efficiency when displaying an image. As described above with reference to FIG. 2 , when a phase modulator is used, the hologram can be formed by adjusting the phase of incident light, eliminating the need to block the incident light and improving the light utilization efficiency. By improving the light utilization efficiency, it is possible to increase the contrast of the displayed image and reduce the power consumption of the light source 2.

[0055] Furthermore, in this embodiment, pixel position shifting in shift multiplexed display is performed by spatial light modulation, eliminating the need for a shift device (e.g., a device that vibrates a spatial light modulator) for pixel position shifting. If a shift device is used, a transition period occurs until the pixel positions are completely shifted, during which image display is not possible, resulting in low efficiency. When pixel position shifting is achieved by spatial light modulation as in this embodiment, such a transition period does not occur, thereby improving efficiency. Furthermore, since the shift device is not required, the width of pixel position shifting does not depend on the shift device, enabling improved display density. Therefore, it is possible to achieve highly accurate resolution degradation correction, such as a quarter-pixel shift.

[0056] This embodiment also corrects for degradation due to disclination in the liquid crystal panel, which eliminates the need to use a liquid crystal panel with a large pixel pitch to address disclination or a liquid crystal panel with four or more times the number of pixels of the reproduced image, thereby enabling the holographic projector device 1 to be made smaller and more affordable.

[0057] Furthermore, in this embodiment, the deterioration caused by optical aberrations such as lens distortion is also corrected, which eliminates the need to use expensive lenses with aberration correction functions, thereby enabling the holographic projector device 1 to be manufactured at a lower price.

[0058] [1-3. Processing Procedure] Fig. 6 is a flowchart showing an example of a specific processing procedure to be executed by the control unit 11 to realize the degradation correction method as the first embodiment described above. When a moving image is displayed, the control unit 11 sets frame images constituting the moving image as target images and executes the processing shown in Fig. 6 for each frame image. When a still image is displayed, the control unit 11 may repeatedly execute the processing shown in Fig. 6 for a common target image.

[0059] First, in step S101, the control unit 11 calculates a hologram that reproduces a target image as an undegraded hologram. That is, the undegraded hologram is calculated based on the target image using the above-mentioned [Equation 1].

[0060] In step S102, which follows step S101, the control unit 11 calculates a degraded hologram based on the pre-degraded hologram and the degradation element information. Specifically, in this example, the controller 11 calculates a degraded hologram by performing processing to impart to the pre-degraded hologram the resolution degradation due to the optical filter 9, the degradation of the reconstructed image due to the disclination, and the degradation of the reconstructed image due to the optical aberration, based on information on the resolution degradation element due to the optical filter 9 (the "Mask" described above), information on the degradation element of the reconstructed image due to the disclination (the "d" described above), and information on the degradation element of the reconstructed image due to the optical aberration, all of which are stored in the memory as degradation element information. Note that the specific calculation method for imparting degradation has already been described, so a duplicate description will be avoided.

[0061] In step S103 following step S102, the control unit 11 calculates the reconstructed image from the degraded hologram as a degraded image. That is, the degraded image is calculated from the degraded hologram by wavefront propagation calculation as described above.

[0062] In step S104 following step S103, the control unit 11 calculates a multiplexing image for correcting degradation based on the difference between the calculated degraded image and the target image, and then in the following step S105, calculates a hologram (correction hologram) for each multiplexing image. The calculation methods for the multiplexing image and the correction hologram have already been explained, so a duplicate explanation will be avoided.

[0063] In step S106 following step S105, the control unit 11 calculates a spatial light modulation pattern for forming a hologram for each correction hologram. That is, as described above, a phase hologram is extracted for each correction hologram to obtain information on the phase distribution on the phase modulation plane, and then drive signal values ​​for each pixel of the phase modulator to realize that phase distribution are calculated as the spatial light modulation pattern.

[0064] In step S107 following step S106, the control unit 11 outputs the calculated spatial light modulation pattern in a time-division manner. That is, information on the calculated spatial light modulation pattern for each correction hologram is output to the drive unit 12 in a time-division manner.

[0065] After executing the process of step S107, the control unit 11 ends the series of processes shown in FIG.

[0066] 2. Second Embodiment Next, a second embodiment will be described. In the second embodiment, a hologram for image display is formed by spatial light amplitude modulation instead of spatial light phase modulation.

[0067] 7 is a diagram showing an example of the configuration of a holographic projector device 1A according to the second embodiment. In the following description, parts that are the same as parts that have already been described will be assigned the same reference numerals and will not be described again.

[0068] The holographic projector device 1A differs from the holographic projector device 1 of the first embodiment in that a spatial light modulation unit 6A is provided instead of the spatial light modulation unit 6, and a control unit 11A is provided instead of the control unit 11.

[0069] The spatial light modulation unit 6A has a spatial light amplitude modulator (hereinafter sometimes abbreviated as "amplitude modulator") as a spatial light modulator. In this example, a reflective liquid crystal panel is used as the amplitude modulator. In this case, the liquid crystal panel is configured to be able to adjust the amplitude of incident light for each pixel. Specifically, it is configured to be able to adjust the degree of blocking of incident light for each pixel.

[0070] The principle of hologram formation by spatial light amplitude modulation will be explained with reference to Fig. 8. For the sake of explanation, a case where a transmissive modulator is used as the amplitude modulator in the spatial light modulation unit 6A is shown here, but the principle is the same when a reflective modulator is used.

[0071] In the figure, an example is shown in which the spatial light modulation unit 6A has pixels that display white (lowest light blocking level) and pixels that display black (highest light blocking level), and by performing such spatial light amplitude modulation, spherical waves from pixels (white pixels) through which light is transmitted without being blocked cause interference, and the interference causes light to reinforce each other in a certain pattern, forming interference fringes (hologram) in a required pattern. At this time, the hologram pattern can be controlled by the pattern of the amplitude distribution imparted to the incident light in the amplitude modulator, that is, the spatial light modulation pattern of the amplitude modulator.

[0072] The control unit 11A has the same functions as the degraded image estimation unit F1, the multiplexing image generation unit F2, the correction hologram generation unit F3, the modulation pattern generation unit F4, and the output control unit F5 that the control unit 11 has, but differs from the control unit 11 in that the modulation pattern generation unit F4 performs conversion processing corresponding to the case where an amplitude modulator is used for converting the correction hologram into a spatial light modulation pattern. Specifically, for the correction hologram as a complex amplitude hologram obtained in the form shown in the above [Equation 4], ２By extracting the amplitude distribution information (x', y') from the amplitude modulation surface of the spatial light modulation unit 6A, amplitude distribution information on the amplitude modulation surface of the spatial light modulation unit 6A is obtained. In this case, the modulation pattern generation unit F4 obtains the amplitude distribution information as described above for each correction hologram, and then calculates, for each correction hologram, a drive signal value for each pixel of the amplitude modulator that will realize the amplitude distribution indicated by the amplitude distribution information on the amplitude modulation surface. This allows for obtaining information on the spatial light modulation pattern for each correction hologram that corresponds to the case where an amplitude modulator is used.

[0073] Furthermore, in the second embodiment, when correcting degradation due to disclination of a liquid crystal panel, the degraded image estimation unit F1 does not apply degradation to the pre-degraded hologram using the above-mentioned [Equation 2], but rather applies degradation using the following [Equation 5].

[0074] By adopting a technique for forming a hologram by spatial light amplitude modulation as in the second embodiment, it is possible to use an amplitude modulation type spatial light modulator that is generally used for image display as the spatial light modulator.

[0075] 3. Third Embodiment In the third embodiment, the degradation correction of a reproduced image is performed only on a partial image region, such as a region of interest as an image region that is attracting the user's attention.

[0076] 9 is a diagram showing an example of the configuration of a holographic projector device 1B according to a third embodiment. The difference from the holographic projector device 1 shown in FIG. 1 is that a control unit 11B is provided instead of the control unit 11.

[0077] The control unit 11B controls the spatial light modulation unit so that a correction hologram is formed only in a specified partial image area of ​​the reproduced image. Specifically, in this example, attention area designation information is input to the control unit 11B. This attention area designation information is information that designates the user's attention area, i.e., the image area in the displayed image that the user is focusing on.

[0078] Here, the attention area may be determined based on the results of estimating the user's gaze direction, facial orientation, etc. based on a captured image of the user obtained by a camera installed inside or outside the holographic projector device 1B. Alternatively, the attention area may be specified by a user operation. In the former case, it is assumed that the estimation process of the user's gaze direction, facial orientation, etc. and the setting process of the attention area based on the estimation results are performed outside the control unit 11B. In this case, information indicating the attention area set externally is input to the control unit 11B as attention area designation information. Note that the estimation process and the setting process of the attention area based on the estimation results may be performed by the control unit 11B itself. Alternatively, it is also possible to perform only the estimation process outside the control unit 11B, and the setting process of the attention area based on the estimation results may be performed by the control unit 11B. In the latter case, it is also possible that the setting process of the attention area based on the user operation is performed by the control unit 11B. In this case, information about the operation performed by the user to designate the attention area is input to the control unit 11B as attention area designation information.

[0079] The region of interest may also be identified by image analysis of the target image, for example, by using an artificial intelligence model that has undergone machine learning such as deep learning to infer the region of interest from the input image.

[0080] The control unit 11B in this example calculates a plurality of multiplexing images to be used for shift multiplexing display and calculates a correction hologram for each multiplexing image only for the region of interest specified by the region of interest specification information.

[0081] 10 is an explanatory diagram of a degradation correction method according to a third embodiment. First, as indicated by <1> in the diagram, the control unit 11B calculates a whole hologram from the target image. This process, similar to the process in step S101 above, calculates an undegraded hologram from the target image. In the second embodiment, the undegraded hologram for the entire target image is referred to as the whole hologram.

[0082] Furthermore, as indicated by <2> in the figure, the control unit 11B generates a multiplexing image for the region of interest based on the target image. Then, as indicated by <3> in the figure, the control unit 11B converts each multiplexing image for the region of interest into a hologram to obtain multiple correction holograms. The control unit 11B then synthesizes the correction hologram generated in <3> with the overall hologram calculated in <1> above. This synthesis with the overall hologram is performed for each correction hologram. Subsequently, each synthesized hologram is converted into a spatial light modulation pattern, and the spatial light modulation pattern for each synthesized hologram is output to the drive unit 12 in a time-division manner. This enables degradation correction limited to the region of interest.

[0083] 11 is an explanatory diagram of the functions of the control unit 11B. As shown in the figure, the control unit 11B differs from the control unit 11 in that it has a function as a degraded image estimation unit F1B instead of the degraded image estimation unit F1, a function as a multiplexing image generation unit F2B instead of the multiplexing image generation unit F2, and the functions of a whole hologram calculation unit F6 and a synthesis unit F7 have been added.

[0084] The degraded image estimation unit F1B generates a degraded image for the region of interest based on the target image, the degradation element information, and the region of interest designation information. The processing performed by this degraded image estimation unit F1B is the same as the processing performed by the degraded image estimation unit F1, except that the image region to be processed is limited to the region of interest, so a duplicated description will be avoided.

[0085] The image for multiplexing generation unit F2B generates an image for multiplexing of the region of attention by calculation based on the degraded image for the region of attention obtained by the degraded image estimation unit F1B, the target image, and the region of attention designation information. Specifically, the image for multiplexing generation unit F2B generates an image for multiplexing of the region of attention based on the difference between the image of the region of attention in the target image and the degraded image for the region of attention obtained by the degraded image estimation unit F1B. This processing is similar to the processing of the image for multiplexing generation unit F2 except that the image region to be processed is limited to the region of attention, so a duplicated description will be avoided.

[0086] In this case, the correction hologram generation unit F3 converts each multiplexing image of the area of ​​interest generated by the multiplexing image generation unit F2B into a hologram, thereby obtaining each correction hologram for the area of ​​interest (see <3> in Figure 10).

[0087] The whole hologram calculation unit F6 obtains a whole hologram by performing calculations to convert the target image into a hologram. The synthesis unit F7 synthesizes the whole hologram obtained by the whole hologram calculation unit F6 with a correction hologram for the region of interest obtained by the correction hologram generation unit F3. As described above, synthesis with the whole hologram is performed for each correction hologram. In other words, in this example, four correction holograms are generated, and therefore four synthesized holograms are obtained, each with a different correction hologram.

[0088] In this case, the modulation pattern generation unit F4 converts each composite hologram obtained by the combination unit F7 into a spatial light modulation pattern, and the output control unit F5 outputs the spatial light modulation pattern for each composite hologram obtained by the modulation pattern generation unit F4 to the drive unit 12 in a time-division manner.

[0089] Fig. 12 is a flowchart showing an example of a specific processing procedure executed by the control unit 11B to realize the degradation correction method as the third embodiment described above. Note that, in the processing shown in Fig. 12, similar to the processing shown in Fig. 6, when a moving image is displayed, the frame images constituting the moving image are used as target images and the illustrated processing is executed for each frame image, and when a still image is displayed, the illustrated processing is executed repeatedly for a common target image.

[0090] First, in step S101, the control unit 11B calculates a hologram that reproduces a target image as a pre-deterioration hologram (whole hologram). This process corresponds to the process described above for the whole hologram calculation unit F6.

[0091] In response to execution of the process of step S101, the control unit 11B advances the process to step S201. In step S201, the control unit 11B calculates a degraded hologram for the region of attention based on the undegraded hologram of the region of attention, the degradation element information, and the region of attention designation information. That is, based on the region of attention designation information, the image of the region of attention in the target image is converted into a hologram to obtain an undegraded hologram of the region of attention, and various degradations are imparted to the undegraded hologram of the region of attention using the degradation element information, thereby obtaining a degraded hologram of the region of attention.

[0092] In step S202 following step S201, the control unit 11B calculates a degraded image of the region of interest based on the calculated degraded hologram. Then, in step S203 following step S202, the control unit 11B calculates a multiplexing image of the region of interest based on the difference between the degraded image of the region of interest and the image of the region of interest in the target image, and then in step S204, calculates a hologram of the multiplexing image (correction hologram). The processing of steps S203 and S204 corresponds to the processing of the above-mentioned multiplexing image generation unit F2B and correction hologram generation unit F3, respectively.

[0093] In step S205 following step S204, the control unit 11B performs a synthesis process of the whole hologram (pre-deterioration hologram) and the correction hologram. That is, this process synthesizes the whole hologram (pre-deterioration hologram calculated in step S101) with each correction hologram calculated in step S204. As described above, synthesis with the whole hologram is performed for each correction hologram.

[0094] In step S206 following step S205, the control unit 11B converts each composite hologram into a spatial light modulation pattern, and in the subsequent step S207, outputs the spatial light modulation pattern in a time-division manner.

[0095] After executing the process of step S207, the control unit 11B ends the series of processes shown in FIG.

[0096] The technique of performing degradation correction by confining it to a partial image region as in the third embodiment can also be applied to the case where an amplitude modulator is used as the spatial light modulator as in the second embodiment.

[0097] 4. Modifications Although various embodiments according to the present technology have been described above, the present technology is not limited to the specific examples described above and may adopt configurations as various modifications. For example, in the above description, the calculation of the correction hologram is performed on the assumption that a two-dimensional flat reconstruction surface is used. However, the calculation of the correction hologram may also be performed on the assumption that the reconstruction surface has projections and recesses.

[0098] For example, as shown in Fig. 13, the actual reproduction surface may not be a two-dimensional plane indicated by "I" in the figure, but may be a surface with relatively large concaves and convexes. In this case, particularly assuming that a light diffusion element such as a microlens array, HOE (Holographic Optical Element), DOE (Diffractive Optical Element), or the like is arranged on the reproduction surface to improve the viewing angle characteristics, if hologram calculation is performed assuming a two-dimensional plane as the reproduction surface, the imaging positions of the light rays of the reproduction image will not coincide with the positions of the diffusion element, that is, defocusing with respect to the diffusion element will occur, and the diffusion element will not properly diffuse the light, preventing the improvement of the viewing angle characteristics.

[0099] Therefore, the correction hologram is calculated assuming that the reconstruction surface is an uneven surface, as shown in Fig. 14. Specifically, three-dimensional information indicating the uneven shape of the reconstruction surface is measured in advance, and the measured three-dimensional information is used as the three-dimensional information of the assumed reconstruction surface in the calculation of the correction hologram.

[0100] 15 is a diagram illustrating a holographic projector device 1C that calculates a correction hologram using three-dimensional information about the reproduction plane as described above. Specifically, it is a diagram illustrating the functions of a control unit 11C that holographic projector device 1C has. Note that the configuration of holographic projector device 1C, other than control unit 11C, is similar to that of holographic projector device 1 described in the first embodiment, for example, and therefore a duplicated description will be avoided.

[0101] Control unit 11C differs from control unit 11 in that it has a correction hologram generation unit F3C instead of correction hologram generation unit F3. Measured three-dimensional information of the reproduction surface is input to correction hologram generation unit F3C as reproduction surface three-dimensional information. Here, the reproduction surface three-dimensional information, like the degradation element information, may be stored in a memory that can be read by control unit 11C.

[0102] The correction hologram generation unit F3C uses the coordinate information indicated by the three-dimensional reconstruction surface information as the coordinate information of the reconstruction surface assumed in calculating the correction hologram. This makes it possible to calculate an appropriate correction hologram for correcting resolution degradation in cases where the actual reconstruction surface has unevenness. In particular, when the above-mentioned diffusion element is arranged on the reconstruction surface, it is possible to align the focusing position of each light beam of the reconstruction image with the position of the diffusion element, thereby improving the viewing angle characteristics.

[0103] Here, in the explanation so far, an example of displaying a 2D image has been given, but the present technology can also be suitably applied to the case of displaying a 3D image.

[0104] This technology can also be suitably applied to the display of color images. For example, a configuration can be considered in which a spatial light modulator for each color (R, G, B) is provided, a correction hologram is generated for each color based on a target image and a degraded image, and a shift multiplexed display is performed using the generated correction hologram. Alternatively, a single-plate spatial light modulator can be configured to define a spatial light modulation area for each color, and each spatial light modulation area can be treated as a color-specific spatial light modulator. Similarly, a correction hologram is generated for each color based on a target image and a degraded image, and a shift multiplexed display is performed using the generated correction hologram. The above configuration for displaying color images allows the reconstructed images of each color to be displayed simultaneously rather than in a time-division manner, thereby suppressing color breakup. Note that, if color breakup can be ignored, a configuration can be considered in which a shift multiplexed display using correction holograms generated for each color is performed in a time-division manner.

[0105] Furthermore, while the explanation so far has been given of an example in which resolution degradation correction is performed using shift multiplexing display, it is also possible to realize resolution degradation correction by, for example, generating a single correction hologram that cancels the difference between a target image and a degraded image and forming the correction hologram using a spatial light modulation unit. In this case, the correction hologram may be generated by, for example, calculating a blur function for each pixel of the degraded image, multiplying the pixel value for each pixel of the target image by the inverse function of the blur function to generate a correction image, and then generating a hologram that reproduces the correction image.

[0106] Furthermore, in the above description, an example has been given in which a semiconductor laser is used as the light source 2, but it is also possible to use a light emitting element other than a semiconductor laser, such as an LED (Light Emitting Diode), as the light source 2.

[0107] Furthermore, in the above description, an example has been given in which a reflective liquid crystal panel is used as a spatial light modulator for forming a hologram, but it is also possible to use a reflective spatial light modulator other than a liquid crystal panel. For example, when a phase modulator is used as in the first embodiment, it is possible to use a mirror using MEMS (Micro Electro Mechanical Systems), specifically, a MEMS mirror configured to allow the height of the mirror surface to be adjusted for each pixel. Furthermore, when an amplitude modulator is used as in the second embodiment, it is possible to use a DMD (Digital Micro Mirror Device). It is also possible to use a transmissive spatial light modulator instead of a reflective spatial light modulator.

[0108] 5. Summary of the Embodiments As described above, the holographic projector device (1, 1A, 1B, 1C) according to the embodiment includes a light source (2), a spatial light modulation unit (6, 6A) that performs spatial light modulation on light emitted from the light source, a projection unit (relay lenses 7, 8, projection lens 10) that projects a reconstructed image generated by the spatial light modulation unit, and a control unit (11, 11A, 11B, 11C) that calculates a correction hologram for correcting degradation of the reconstructed image based on a target image and degradation element information indicating at least resolution degradation elements of the reconstructed image that occur along the projection path from the light source to the projection unit, and controls the spatial light modulation unit to be driven by a spatial light modulation pattern based on the calculated correction hologram. This configuration enables resolution degradation correction that takes into account resolution degradation elements that actually occur along the projection path, thereby enabling appropriate resolution degradation correction. Furthermore, resolution degradation correction allows the use of a low-resolution spatial light modulator. Therefore, the holographic projector device can be manufactured at a low price while suppressing degradation in resolution.

[0109] Furthermore, the holographic projector device according to the embodiment includes an optical filter (see reference 9) that applies optical filtering to the reproduced image, and the degradation factor information includes information on resolution degradation factors caused by the optical filter, which allows for resolution degradation correction in cases where the resolution degradation factors are caused by the optical filter.

[0110] Furthermore, in the holographic projector device according to the embodiment, the optical filter is an optical filter that removes noise light. The optical filter that removes noise light can cause degradation in the resolution of the reproduced image. Therefore, it is preferable to correct the resolution degradation by taking into account the resolution degradation caused by the optical filter.

[0111] Furthermore, in an embodiment of the holographic projector, the spatial light modulation unit performs spatial light modulation using a liquid crystal panel, and the degradation factor information includes information on degradation factors of the reproduced image that occur in the liquid crystal panel, thereby making it possible to correct degradation of the reproduced image in response to cases where degradation factors of the reproduced image occur in the liquid crystal panel used for spatial light modulation.

[0112] Furthermore, in the holographic projector device according to the embodiment, the degradation factor information includes information on degradation factors of the reproduced image caused by disclinations in the liquid crystal panel. This allows for correction of degradation of the reproduced image caused by disclinations, eliminating the need to use liquid crystal panels with a large pixel pitch or liquid crystal panels with four or more times the number of pixels of the reproduced image to address disclinations. This allows for the miniaturization and cost reduction of the holographic projector device.

[0113] Furthermore, in the holographic projector device according to the embodiment, the degradation factor information includes information indicating degradation factors that occur in the reproduced image due to optical aberrations. This makes it possible to calculate a corrective hologram that can correct not only degradation in resolution but also degradation in the reproduced image due to optical aberrations, such as lens distortion in a projection lens system. This improves the image quality of the displayed image.

[0114] Furthermore, in a holographic projector device according to an embodiment, the control unit controls the spatial light modulation unit so that degradation is corrected by a technique of shifting and multiplexing a plurality of reconstructed images. By performing shift and multiplexing display, a high-resolution image can be displayed using a low-resolution reconstructed image. In other words, resolution degradation correction based on so-called super-resolution technology can be achieved.

[0115] In addition, in the holographic projector device according to the embodiment, the control unit controls the spatial light modulation unit to form multiple correction holograms for shift multiplexed display in a time-division manner. By forming multiple correction holograms for shift multiplexed display in a time-division manner as described above, it becomes possible to shift the reconstructed image for shift multiplexed display using these correction holograms. By shifting the reconstructed image through time-division formation of correction holograms, it becomes unnecessary to provide a shift device for shifting the position of the reconstructed image on the reconstruction surface when realizing shift multiplexed display. This reduces the number of components required to correct resolution degradation, thereby enabling the holographic projector device to be made smaller, lighter, and more affordable.

[0116] Furthermore, in a holographic projector device according to an embodiment, the control unit calculates a hologram reproducing a target image as an undegraded hologram, calculates a degraded hologram based on the undegraded hologram and the degradation element information, calculates a reconstructed image using the degraded hologram as a degraded image, calculates multiple multiplexing images to be used for shift multiplexing display based on the difference between the calculated degraded image and the target image, calculates a hologram for obtaining the multiplexing image as a reconstructed image as a correction hologram for each calculated multiplexing image, and controls the spatial light modulation unit to form the correction hologram for each calculated multiplexing image in a time-division manner. By forming the correction hologram for each multiplexing image in a time-division manner as described above, the correction holograms shift the reconstructed image for shift multiplexing display. Therefore, there is no need to provide a shift device for shifting the position of the reconstructed image on the reconstruction surface to achieve shift multiplexing display, which reduces the number of parts required to correct resolution degradation and enables the holographic projector device to be made smaller, lighter, and more affordable.

[0117] Furthermore, in the holographic projector devices (1, 1B, and 1C) according to the embodiments, the spatial light modulation unit performs spatial light phase modulation as the spatial light modulation. By generating a reproduced image using spatial light modulation, it is possible to improve the efficiency of light utilization in image display, thereby achieving high contrast in the displayed image and reducing the power consumption of the light source.

[0118] In addition, in the holographic projector device (1B) according to the embodiment, the control unit (11B) controls the spatial light modulation unit so that a correction hologram is formed only in a specified portion of the image area of ​​the reproduced image. This makes it possible to perform calculations for correcting resolution degradation only in a portion of the image that particularly requires correction, such as an image area that the user is paying attention to. This reduces the calculation processing load required for correcting resolution degradation.

[0119] Furthermore, in the holographic projector device according to the embodiment, the control unit (11C) calculates a correction hologram assuming an uneven reproduction surface, thereby enabling calculation of an appropriate correction hologram for correcting resolution degradation even when the actual reproduction surface is uneven.

[0120] Furthermore, a control method as an embodiment is a control method for a holographic projector device including a light source, a spatial light modulation unit that performs spatial light modulation on light emitted from the light source, and a projection unit that projects a reconstructed image generated by the spatial light modulation unit, the control method comprising: calculating a correction hologram for correcting degradation of the reconstructed image based on a target image and degradation factor information that indicates at least resolution degradation factors of the reconstructed image that occur along the projection path from the light source to the projection unit; and controlling the spatial light modulation unit to be driven by a spatial light modulation pattern based on the calculated correction hologram. Such a control method can also achieve the same functions and effects as the holographic projector device as the above-described embodiment.

[0121] The effects described in this specification are merely examples and are not limiting, and other effects may also be present.

[0122] <6. The Present Technology> The present technology may also have the following configurations. (1) A holographic projector device comprising: a light source; a spatial light modulation unit that performs spatial light modulation on light emitted from the light source; a projection unit that projects a reconstructed image generated by the spatial light modulation unit; and a control unit that calculates a correction hologram for correcting degradation of the reconstructed image based on a target image and degradation element information that is information indicating at least resolution degradation elements of the reconstructed image that occur along a projection path from the light source to the projection unit, and controls the spatial light modulation unit to be driven by a spatial light modulation pattern based on the calculated correction hologram. (2) The holographic projector device described in (1) above, including an optical filter that performs optical filtering on the reconstructed image, wherein the degradation element information includes information on resolution degradation elements caused by the optical filter. (3) The holographic projector device described in (2) above, wherein the optical filter is an optical filter that removes noise light. (4) The holographic projector device according to any one of (1) to (3), wherein the spatial light modulation unit performs the spatial light modulation using a liquid crystal panel, and the degradation element information includes information on degradation elements of the reconstructed image that occur in the liquid crystal panel. (5) The holographic projector device according to (4), wherein the degradation element information includes information on degradation elements of the reconstructed image caused by disclinations in the liquid crystal panel. (6) The holographic projector device according to any one of (1) to (5), wherein the degradation element information includes information on degradation elements caused by optical aberrations that occur in the reconstructed image. (7) The holographic projector device according to (1), wherein the control unit controls the spatial light modulation unit so that the degradation is corrected by a technique of shift-multiplexing displaying a plurality of reconstructed images. (8) The holographic projector device according to (7), wherein the control unit controls the spatial light modulation unit so that a plurality of the correction holograms for the shift-multiplexing display are formed in a time-division manner.(9) The holographic projector device according to any one of (8) to (9), wherein the control unit calculates a hologram reproducing the target image as an undegraded hologram, calculates a degraded hologram based on the undegraded hologram and the degradation element information, calculates a reproduced image from the degraded hologram as a degraded image, calculates a plurality of multiplexing images to be used for the shift multiplexing display based on a difference between the calculated degraded image and the target image, calculates a hologram as the correction hologram for obtaining the multiplexing image as a reproduced image for each of the calculated multiplexing images, and controls the spatial light modulation unit to form the correction hologram for each of the calculated multiplexing images in a time-division manner. (10) The holographic projector device according to any one of (1) to (9), wherein the spatial light modulation unit performs spatial light phase modulation as the spatial light modulation. (11) The holographic projector device according to any one of (1) to (10), wherein the control unit controls the spatial light modulation unit so that the correction hologram is formed only in a specified partial image region in the reconstructed image. (12) The holographic projector device according to any one of (1) to (11), wherein the control unit calculates a hologram assuming a reconstruction surface having projections and depressions to calculate the correction hologram. (13) A control method for a holographic projector device including a light source, a spatial light modulation unit that performs spatial light modulation on light emitted from the light source, and a projection unit that projects the reconstructed image generated by the spatial light modulation unit, the control method comprising: calculating a correction hologram for correcting degradation of the reconstructed image based on a target image and degradation element information that is information indicating at least resolution degradation elements of the reconstructed image that occur on a projection path from the light source to the projection unit; and controlling the spatial light modulation unit to be driven by a spatial light modulation pattern based on the calculated correction hologram.

[0123] REFERENCE SIGNS LIST 1, 1A, 1B, 1C holographic projector device 2 light source 3 beam expander 4 collimator lens 5 beam splitter 6, 6A spatial light modulation section 7, 8 relay lens 9 optical filter 10 projection lens 11, 11A, 11B, 11C control section 12 drive section S screen F1, F1A degraded image estimation section F2, F2B multiplexing image generation section F3, F3C correction hologram generation section F4 modulation pattern generation section F5 output control section F6 overall hologram calculation section F7 synthesis section

Claims

1. A holographic projector device comprising: a light source; a spatial light modulation unit which performs spatial light modulation on the light emitted from the light source; a projection unit which projects a reconstructed image generated by the spatial light modulation unit; and a control unit which calculates a correction hologram for correcting degradation of the reconstructed image based on a target image and degradation element information which is information indicating at least resolution degradation elements of the reconstructed image which occur on the projection path from the light source to the projection unit, and controls the spatial light modulation unit to be driven by a spatial light modulation pattern based on the calculated correction hologram.

2. The holographic projector device according to claim 1, further comprising an optical filter that applies optical filtering to the reconstructed image, and wherein the degradation factor information includes information on resolution degradation factors caused by the optical filter.

3. The holographic projector device according to claim 2, wherein the optical filter is an optical filter for removing noise light.

4. The holographic projector device according to claim 1, wherein the spatial light modulation section performs the spatial light modulation using a liquid crystal panel, and the degradation factor information includes information on degradation factors of the reproduced image that occur in the liquid crystal panel.

5. The holographic projector device according to claim 4, wherein the degradation element information includes information on degradation elements of the reproduced image caused by disclinations in the liquid crystal panel.

6. The holographic projector device according to claim 1, wherein the degradation element information includes information indicating degradation elements caused by optical aberrations occurring in the reconstructed image.

7. The holographic projector device according to claim 1, wherein the control unit controls the spatial light modulation unit so that the deterioration is corrected by a method of shifting and multiplexing a plurality of reconstructed images to be displayed.

8. The holographic projector device according to claim 7, wherein the control unit controls the spatial light modulation unit so that a plurality of correction holograms for the shift multiplexed display are formed in a time-division manner.

9. The holographic projector device of claim 8, wherein the control unit: calculates a hologram reproducing the target image as an undegraded hologram; calculates a degraded hologram based on the undegraded hologram and the degradation element information; calculates a reconstructed image from the degraded hologram as a degraded image; calculates a plurality of multiplexing images to be used for the shift multiplexing display based on the difference between the calculated degraded image and the target image; calculates a hologram for obtaining the multiplexing image as a reconstructed image as the correction hologram for each of the calculated multiplexing images; and controls the spatial light modulation unit so that the correction hologram for each calculated multiplexing image is formed in a time-division manner.

10. The holographic projector device according to claim 1, wherein the spatial light modulation section performs spatial light phase modulation as the spatial light modulation.

11. The holographic projector device according to claim 1, wherein the control unit controls the spatial light modulation unit so that the correction hologram is formed only in a specified partial image area in the reconstructed image.

12. The holographic projector device according to claim 1, wherein the control unit calculates a hologram assuming a reproduction surface having projections and recesses in order to calculate the correction hologram.

13. A control method for a holographic projector device comprising a light source, a spatial light modulation unit which performs spatial light modulation on the light emitted from the light source, and a projection unit which projects a reconstructed image generated by the spatial light modulation unit, the control method comprising the steps of: calculating a correction hologram for correcting degradation of the reconstructed image based on a target image and degradation element information which is information indicating at least resolution degradation elements of the reconstructed image occurring on the projection path from the light source to the projection unit; and controlling the spatial light modulation unit to be driven by a spatial light modulation pattern based on the calculated correction hologram.

Images