Computer-generated holographic display system and method

Abstract

The invention provides a computer-generated hologram display system and method, and the system comprises a control element which is used for obtaining a target scene image of a first resolution, calculating holographic surface complex amplitude information based on the target scene image, and carrying out the coding of the information, thereby obtaining a hologram sequence; the spatial light modulator is used for loading the hologram sequence and modulating the incident light beam according to the hologram sequence to obtain a diffraction image sequence; and the parallel plate modulation element is used for holographically displaying the diffraction image sequence on the image surface according to the target offset by controlling the rotation angle of the parallel plate modulation element. According to the system, a parallel plate modulation element is introduced between a spatial light modulator and an image plane, and high-resolution mapping of a low-resolution hologram on an object plane is ensured through complex amplitude data compensation, so that the modulation capability of the hologram on the spatial light modulator with limited resolution is improved; the computer-generated hologram display performance with higher resolution is achieved, long-time preparation through a complex process is not needed, and the cost of holographic super-resolution display is reduced.

Description

Technical Field

[0001] The present invention relates to the field of holographic display technology, and in particular to a computer-generated holographic display system and method. Background Art

[0002] Computer-generated hologram (CGH) technology can reproduce the amplitude and phase information of the object light wave by using a spatial light modulator (SLM) to load a computer-generated hologram (CGH), thereby reproducing a three-dimensional image. This technology is regarded as one of the ultimate ways to achieve three-dimensional display, because it can provide the depth perception clues required by the human eye and present realistic three-dimensional visual effects. It is widely used in virtual reality, augmented reality, medical imaging, scientific research and other fields.

[0003] However, current computer-generated holographic display systems face significant challenges in terms of information transmission efficiency. Specifically, due to the inherent spatial bandwidth product of spatial light modulators, the display resolution of existing systems is difficult to break through the pixel number limit of the modulation device and cannot meet the needs of ultra-high-resolution all-optical information modulation.

[0004] In order to solve the above-mentioned resolution bottleneck problem, the existing mainstream methods at home and abroad are mainly focused on improvements at the hardware level. A common strategy is to prepare light modulators with ultra-high pixel density. Although this method can theoretically improve the resolution, its high cost, long preparation cycle and complex process requirements make large-scale applications impractical. Another common solution is to increase the number of effective pixels by splicing multiple spatial light modulators. Although this method improves the resolution to a certain extent, it also brings new problems, such as splicing errors, calibration complexity and the stability of the overall system. These methods not only increase the complexity and cost of the system, but also make it difficult to achieve the requirements of real-time dynamic holographic display, and cannot meet the needs of modern applications for high resolution and fast response.

[0005] Therefore, how to solve the problems that the existing computer-generated holographic display system is limited by the inherent spatial-bandwidth product of spatial light modulation devices, making it difficult to achieve ultra-high-resolution all-optical information modulation, and the ultra-high pixel density light modulation devices have complex processes, long preparation cycles, high costs, and cannot achieve real-time dynamic holographic display, is an important issue that needs to be urgently solved in the field of holographic display. Summary of the invention

[0006] The present invention provides a computer-generated holographic display system and method, which are used to overcome the defects of existing computer-generated holographic display systems that are limited by the inherent spatial-bandwidth product of spatial light modulation devices and are difficult to achieve ultra-high-resolution all-optical information modulation and real-time dynamic holographic display, and achieve higher-resolution computer-generated holographic display performance without the need for complex processes and long-term preparation, thereby greatly reducing the cost of holographic super-resolution display.

[0007] On the one hand, the present invention provides a computer holographic display system, comprising: a control element, used to obtain a target scene image of a first resolution, calculate and encode the complex amplitude information of the holographic surface based on the target scene image, and obtain a hologram sequence; a spatial light modulator, connected to the control element, used to load the hologram sequence, and modulate an incident light beam according to the hologram sequence to obtain a diffraction image sequence; a parallel plate modulation element, connected to the spatial light modulator, used to holographically display the diffraction image sequence on the image plane according to the target offset by controlling its own rotation angle.

[0008] Furthermore, the control element is specifically used to divide the target scene image into an object light image sequence of a second resolution; calculate and encode the complex amplitude information of the holographic surface corresponding to the object light image sequence to obtain a global transmittance function sequence; wherein the first resolution is higher than the second resolution, and the global transmittance function sequence is the hologram sequence.

[0009] Furthermore, the target offset is calculated based on a plurality of key element parameters of the parallel plate modulation element; wherein the plurality of key element parameters include refractive index, thickness and rotation angle.

[0010] Further, the target offset is calculated based on the pixels of the spatial light modulator and the number of diffraction images in the diffraction image sequence.

[0011] Further, the relationship between the target scene image of the first resolution and the object light image sequence of the second resolution is as follows: ; in, represents the target scene image, Indicates the first resolution, Indicates the number of pixels in the horizontal direction. Indicates the number of pixels in the vertical direction. represents the object light image sequence, Indicates the second resolution, Indicates the number of object light images in the object light image sequence.

[0012] Furthermore, the calculation formula of the target offset is as follows: ; in, Indicates The target offset of the diffraction image, represents the thickness of the parallel plate modulation element, Indicates The rotation angle corresponding to the diffraction image is, represents the refractive index of the parallel-plate modulation element.

[0013] Furthermore, the calculation formula of the complex amplitude information of the holographic surface corresponding to the object light image sequence is as follows: ; ; in, Indicates the first The complex amplitude information of the holographic surface corresponding to the object light image, represents the Fourier transform, represents the inverse Fourier transform, Indicates An object light image, represents the holographic surface angle spectrum diffraction transfer function, represents the imaginary unit, represents the wave number, represents the diffraction propagation distance, represents the wavelength, , Represent the sampling frequency in the horizontal and vertical directions respectively.

[0014] In a second aspect, the present invention further provides a computer-generated holographic display method, which is applied to the computer-generated holographic display system described in any of the above items, comprising: acquiring a target scene image of a first resolution; calculating and encoding the complex amplitude information of the holographic surface based on the target scene image to obtain a hologram sequence; controlling the spatial light modulator to load the hologram sequence, and modulating the incident light beam according to the hologram sequence to obtain a diffraction image sequence; and holographically displaying the diffraction image sequence on the image plane according to the target offset by controlling the rotation angle of the parallel plate modulation element.

[0015] Furthermore, the holographic surface complex amplitude information is calculated based on the target scene image and encoded to obtain a hologram sequence, including: dividing the target scene image into an object light image sequence of a second resolution; calculating the holographic surface complex amplitude information corresponding to the object light image sequence; encoding the holographic surface complex amplitude information corresponding to the object light image sequence to obtain a global transmittance function sequence; wherein the first resolution is higher than the second resolution, and the global transmittance function sequence is the hologram sequence.

[0016] Further, the target offset is calculated based on multiple key component parameters of the parallel plate modulation element, wherein the multiple key component parameters include refractive index, thickness and rotation angle; or, the target offset is calculated based on the number of diffraction images in the pixel and diffraction image sequence of the spatial light modulator.

[0017] The computer holographic display system provided by the present invention includes a control element, a spatial light modulator, a parallel flat plate modulation element and an image plane, wherein the control element is used to obtain a target scene image of a first resolution, calculate the complex amplitude information of the holographic surface based on the target scene image and encode it to obtain a hologram sequence; the spatial light modulator is connected to the controlled element, used to load the hologram sequence, and modulate the incident light beam according to the hologram sequence to obtain a diffraction image sequence; the parallel flat plate modulation element is connected to the spatial light modulator, and is used to holographically display the diffraction image sequence on the image plane according to the target offset by controlling its own rotation angle. The system introduces a parallel flat plate modulation element between the spatial light modulator and the image plane according to the display resolution improvement demand, and ensures the higher resolution mapping of the lower resolution hologram on the object plane through complex amplitude data compensation, thereby improving the modulation capability of the hologram for the limited resolution spatial light modulator, achieving higher resolution computer holographic display performance, and does not require complex process and long-term preparation, which greatly reduces the cost of holographic super-resolution display. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 It is a schematic diagram of a computer-generated holographic display system provided by an embodiment of the present invention.

[0020] Figure 2 It is a schematic diagram of the principle of a computer-generated holographic display system provided by an embodiment of the present invention.

[0021] Figure 3 It is a schematic diagram of the overall implementation process of the computer-generated holographic display system provided by an embodiment of the present invention.

[0022] Figure 4 It is a flowchart of the computer-generated holographic display method provided in an embodiment of the present invention.

[0023] Reference numerals: 110: control element; 120: spatial light modulator; 130: parallel plate modulation element; 140: image plane. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] It should be noted that the information efficiency that can be transmitted by existing computer-generated holographic display systems is limited by the inherent spatial-bandwidth product of the spatial light modulator. The display resolution cannot exceed the number of pixels of the spatial light modulator, making it difficult to achieve ultra-high-resolution all-optical information modulation.

[0026] The existing mainstream solutions at home and abroad mainly enhance the modulation capability of hardware by preparing ultra-high pixel density optical modulation devices, splicing spatial light modulators, etc., so as to achieve the purpose of improving resolution. However, these methods are costly, time-consuming to prepare, and require complex processes, and cannot meet the display requirements of real-time dynamic holograms.

[0027] In view of this, the present invention proposes a new computer-generated holographic display system, which can eliminate the resolution dependence of high-resolution object light waves and spatial light modulators, ensure higher-resolution mapping of lower-resolution holograms in the object plane through complex amplitude data compensation, improve the modulation capability of holograms for limited-resolution spatial light modulators, and achieve higher-resolution computer-generated holographic display performance.

[0028] Specifically, Figure 1 FIG. 1 is a schematic diagram of a computer generated holographic display system provided by an embodiment of the present invention. Figure 1 As shown, the system includes a control element 110, a spatial light modulator 120, a parallel plate modulation element 130 and an image plane 140. The following will describe in detail each module in the computer generated holographic display system provided by the embodiment of the present invention.

[0029] Regarding the control element: The control element is used to obtain a target scene image of a first resolution, calculate and encode the complex amplitude information of the holographic surface based on the target scene image, and obtain a hologram sequence.

[0030] In this embodiment, the control element is the control center of the entire computer holographic display system, responsible for generating, processing and transmitting the hologram data required for reproducing three-dimensional images.

[0031] The target scene image includes amplitude information of the light wave, which represents the maximum intensity or brightness of the light wave and is usually proportional to the light intensity.

[0032] The target scene image can be acquired based on real camera capture or can be obtained through computer rendering, which is not specifically limited here. Among them, the rendering algorithm used by the computer rendering can be selected from ray tracing algorithm, path tracing algorithm, etc.

[0033] In this embodiment, the target scene image of the first resolution is intended to emphasize that the target scene image is a high-resolution image. The specific value of the first resolution, such as 2K resolution, 4K resolution, 5K resolution, 8K resolution, etc., can be determined according to actual needs and is not specifically limited here.

[0034] It is easy to understand that after obtaining the target scene image based on real camera acquisition or computer rendering, the target scene image can be divided into multiple moments using the "time division multiplexing" calculation method. The second resolution object light image sequence .

[0035] Specifically, the target scene image can be segmented into a sequence of object light images by image block segmentation. Specifically, the size of each image block (object light image) is first determined according to the first resolution and requirements of the target scene image; then the target scene image is segmented into a plurality of ( N ) objective light images to obtain an objective light image sequence; finally, the corresponding sub-images are processed / displayed at different times.

[0036] It is worth mentioning that due to the persistence of vision of the human eye, multiple rapid modulations in the time domain can achieve an improvement in the resolution of holographic display.

[0037] The relationship between the target scene image and the object light image sequence obtained by segmentation can be seen in the following formula (1).

[0038] (1).

[0039] In formula (1), represents the target scene image, Indicates the first resolution, Indicates the number of pixels in the horizontal direction. Indicates the number of pixels in the vertical direction. represents the object light image sequence, Indicates the second resolution, Indicates the number of object light images in the object light image sequence.

[0040] According to formula (1), the first resolution is much higher than the second resolution. The second resolution object light image sequence in this embodiment is intended to emphasize that the object light image is a low resolution image compared to the target scene image.

[0041] After obtaining a low-resolution object light image sequence, it is necessary to calculate the complex amplitude information of the holographic surface corresponding to the object light image sequence. This step can be achieved through traditional holographic algorithms or deep learning methods, including but not limited to different methods based on angular spectrum diffraction, Rayleigh Sommerfeld diffraction, Fresnel diffraction, Fraunhofer diffraction, neural network learning, etc.

[0042] In a specific embodiment, the object light image sequence is calculated by an angular spectrum diffraction algorithm. The corresponding holographic surface complex amplitude information is calculated by the following formulas (2)-(3).

[0043] (2).

[0044] (3).

[0045] In formulas (2)-(3), Indicates the first The complex amplitude information of the holographic surface corresponding to the object light image, represents the Fourier transform, represents the inverse Fourier transform, Indicates An object light image, represents the holographic surface angle spectrum diffraction transfer function, represents the imaginary unit, represents the wave number, represents the diffraction propagation distance, represents the wavelength, Represent the sampling frequency in the horizontal and vertical directions respectively.

[0046] In order to ensure that the final hologram can match the performance of the spatial light modulator, the object plane and the holographic plane need to be discretized, and the sampling interval needs to be consistent with the pixel size of the spatial light modulator. The resolution of the holographic surface and the target surface is , then the sampling requirement (sampling frequency) , As shown in formula (4).

[0047] (4).

[0048] Next, the complex amplitude information of the holographic surface corresponding to the object light image sequence is Encoding is performed to obtain a hologram sequence. Taking the spatial light modulator as pure phase modulation as an example, the formula for calculating the global transmittance function of a single hologram is as follows (5): That is, the global transmittance function of a single hologram, i.e., the hologram, and thus a hologram sequence can be obtained. Among them, the hologram sequence corresponds one-to-one to the object light image sequence.

[0049] (5).

[0050] It should be noted that some spatial light modulators are good at phase modulation, some are good at amplitude modulation, and some are capable of mixed modulation. Corresponding to spatial light modulators with different functionalities, the encoding and processing method for the complex amplitude information of the holographic surface should be adaptively adjusted here so that the obtained hologram is suitable for processing by the subsequent spatial light modulator.

[0051] The above steps from acquiring the target scene image to calculating the hologram sequence are all executed by the control element.

[0052] In addition, the control element may also be used to control the light source, adjust the position of the optical element, etc.

[0053] After obtaining the object light image sequence After the corresponding hologram sequence is generated, the control element transmits the hologram sequence to the spatial light modulator and controls the spatial light modulator to load / display the hologram sequence.

[0054] Regarding the spatial light modulator: The spatial light modulator is connected to the control element and is used to load the hologram sequence and modulate the incident light beam according to the hologram sequence to obtain a diffraction image sequence.

[0055] A spatial light modulator is a device that can change the amplitude, phase or polarization state of a light beam through electronic control. The main types of spatial light modulators include liquid crystal spatial light modulator (LC-SLM), digital micromirror device (DMD), magneto-optical spatial light modulator (MO-SLM), acousto-optic modulator (AOM) and electro-optic modulator (EOM). Different types of spatial light modulators have different requirements for hologram encoding.

[0056] In a specific embodiment, the spatial light modulator is an LC-SLM, which utilizes the change in molecular arrangement of liquid crystal materials under an external electric field to change the phase or amplitude of transmitted or reflected light.

[0057] It is easy to understand that after loading the corresponding hologram on the spatial light modulator at different times, a laser with a wavelength suitable for the spatial light modulator (such as a 532nm green laser) is selected to generate a parallel light beam (incident light beam) through a collimating lens to illuminate the surface of the spatial light modulator. The spatial light modulator is placed in the collimated light path so that the incident light is perpendicular to the surface of the spatial light modulator. At the same time, the light reflected or transmitted from the spatial light modulator is collected through a preset lens group to form a diffraction pattern, that is, a diffraction image.

[0058] Thus, a diffraction image sequence can be obtained according to the hologram sequence. There is a one-to-one correspondence between the hologram sequence and the diffraction image sequence.

[0059] It should be noted that the laser, collimating lens, and lens group here can be regarded as a basic optical system. Of course, the optical system can also be replaced by other systems that can achieve the same function, and no specific limitation is made here.

[0060] It should also be noted that according to the optical working mode of the spatial light modulator, it can be divided into a transmissive spatial light modulator and a radial spatial light modulator. The former modulates the light field by controlling the amplitude or phase of the incident light beam when it passes through the device, while the latter modulates the light field by controlling the phase or amplitude of the incident light beam when it is reflected.

[0061] In this embodiment, if the spatial light modulator is transmissive, the direction from the spatial light modulator to the parallel plate modulation element is the direction of the incident light beam; if the spatial light modulator is reflective, the direction from the parallel plate modulation element to the spatial light modulator is the direction of the incident light beam.

[0062] Regarding the parallel plate modulation element: The parallel plate modulation element is connected to the spatial light modulator and is used to holographically display the diffraction image sequence on the image plane according to the target offset by controlling its own rotation angle.

[0063] according to Figure 1 It can be seen that the parallel flat plate modulation element in this embodiment is arranged between the spatial light modulator and the image plane, and is composed of two parallel flat plates (which can be made of materials such as glass or crystal), and the two parallel flat plates can control their own rotation angles as required.

[0064] The parallel plate modulation element in this embodiment is different from the ultra-high pixel density light modulation device, and its refractive index is , thickness is The optical focal length is 0, and there is no need for complex and time-consuming preparation, which can significantly reduce the cost of holographic super-resolution display.

[0065] Among them, the refractive index, thickness, optical focal length and rotation angle are all key component parameters of the parallel plate modulation element. The refractive index, thickness and optical focal length are all determined when preparing the parallel plate modulation element and can be directly applied during actual modulation.

[0066] It is easy to understand that the diffraction image sequence obtained by the spatial light modulator is as the light beam passes through the parallel plate modulation element. The parallel plate modulation element passes at different times. , respectively control their own rotation angles to , to achieve the target offset corresponding to the diffraction image sequence , corresponding to the content / image displayed on the image plane , in order to realize time-division multiplexed holographic scanning super-resolution display.

[0067] In a specific embodiment, the holographic scan is displayed as a random scan, where the target offset The calculation formula is as follows (6).

[0068] (6).

[0069] In formula (6), Indicates The target offset of the diffraction image, represents the thickness of the parallel plate modulation element, Indicates The rotation angle corresponding to the diffraction image is represents the refractive index of the parallel plate modulation element. Each diffraction image corresponds to It is given in advance, and you only need to control the corresponding rotation angle in sequence.

[0070] In another specific embodiment, the holographic scanning is displayed as a uniform scanning, in which case the target offset corresponding to the diffraction image sequence is based on the pixel of the spatial light modulator. p and the number of diffraction images in the diffraction image sequence N Calculated, specifically: .

[0071] About the image plane. The image plane refers to the plane where the image is formed by the focused light beam during the imaging process. As mentioned above, the image plane is used to Displays the diffraction image modulated by the parallel plate modulation element .

[0072] In this embodiment, the computer-generated holographic display system includes a control element, a spatial light modulator, a parallel plate modulation element, and an image plane, wherein the control element is used to obtain a target scene image of a first resolution, calculate the complex amplitude information of the hologram based on the target scene image and encode it to obtain a hologram sequence; the spatial light modulator is connected to the controlled element, used to load the hologram sequence, and modulate the incident light beam according to the hologram sequence to obtain a diffraction image sequence; the parallel plate modulation element is connected to the spatial light modulator, and is used to holographically display the diffraction image sequence on the image plane according to the target offset by controlling its own rotation angle. The system introduces a parallel plate modulation element between the spatial light modulator and the image plane according to the display resolution improvement requirements, and ensures the higher resolution mapping of the lower resolution hologram on the object plane through complex amplitude data compensation, thereby improving the modulation capability of the hologram for the limited resolution spatial light modulator, achieving higher resolution computer-generated holographic display performance, and does not require complex processes and long-term preparation, which greatly reduces the cost of holographic super-resolution display.

[0073] In some embodiments, Figure 2 A schematic diagram showing the principle of a computer generated holographic display system provided by an embodiment of the present invention is shown.

[0074] like Figure 2 As shown, the refractive index of the parallel plate modulation element is , thickness is , the rotation angle is , the three and the target offset The corresponding relationship between them is as shown in formula (6).

[0075] If there is no parallel plane modulation element in this embodiment, the pixel size of the three-dimensional image finally displayed on the image plane is , the resolution is After adding the parallel flat plate modulation element in this embodiment, the pixel size of the three-dimensional image finally displayed on the image plane is , the resolution is .

[0076] This means that the present invention uses a super-resolution implementation method for holographic display based on parallel plate modulation elements, which can break the reliance of the prior art on spatial light modulators with smaller pixel sizes or splicing and joint modulation of multiple spatial light modulators under the condition of a mismatch between the object light and the resolution of the spatial light modulator, and achieve the effect of super-resolution display of a target scene with smaller pixels using a spatial light modulator with larger pixels.

[0077] In some other embodiments, Figure 3 A schematic diagram of the overall implementation process of the computer-generated holographic display system provided by an embodiment of the present invention is shown.

[0078] like Figure 3As shown, before formal implementation, it is necessary to determine the physical parameters of the spatial light modulator, the key component parameters of the parallel plate modulation element, and the physical parameters such as the wavelength of the light source, and perform hardware processing and scanning component assembly based on the determined various physical parameters.

[0079] Among them, the physical parameters of the spatial light modulator include but are not limited to resolution, phase modulation range, refresh rate, response time, diffraction efficiency, etc., and the key component parameters of the parallel plate modulation element include but are not limited to refractive index, thickness and rotation angle, etc.

[0080] When formally carrying out computer-generated holographic display, the following steps (1)-(5) need to be performed.

[0081] (1) High-resolution target scene image acquisition. Obtain high-resolution images of the target scene based on real camera acquisition or computer rendering. .

[0082] (2) Segmentation of low-resolution object light image sequence. Through the concept of time division multiplexing, the target scene image segmentation is obtained. Sequence of object light images displayed at each moment .

[0083] (3) Hologram sequence calculation: By using traditional holographic algorithms or deep learning algorithms, the complex amplitude information of the holographic surface corresponding to the object light image sequence is obtained and encoded, and the hologram sequence corresponding to the object light image sequence can be obtained.

[0084] (4) Holographic scanning time and space alignment. The corresponding hologram is loaded on the spatial light modulator at each moment, and the incident light beam is modulated by the spatial light modulator to obtain the corresponding diffraction image sequence. Subsequently, the diffraction image sequence passes through the parallel plate modulation element, and the target offset corresponding to the diffraction image sequence is achieved by controlling the rotation angle of the parallel plate modulation element.

[0085] (5) Super-resolution holographic scanning display. The diffraction image sequence is holographically displayed on the image plane according to the corresponding target offset, realizing time-division multiplexing scanning super-resolution display.

[0086] It is worth mentioning that the computer-generated holographic display system provided by the present invention has strong application innovation and versatility of display technology.

[0087] Specifically, at the basic theoretical level, the present invention bypasses the bottleneck of the inherent resolution of traditional holographic displays limited by modulation devices, and proposes a new method to improve display resolution to guide the design of higher-resolution holographic display systems for complex scene requirements, thereby improving the visibility of complex information display and the versatility of holographic displays, and can provide basic theoretical support for truly promoting the practical application of computational holographic display systems.

[0088] On the technical level, the present invention generates holograms based on deep learning or scalar diffraction theory, calculates and processes super-resolution computational optical scanning elements suitable for multiple scenarios according to the demand for improving display resolution, and does not require resolution matching between high-resolution target scenes and spatial light modulation devices. A higher-resolution object light field can be displayed directly based on a lower-resolution modulation device.

[0089] Corresponding to the computer-generated holographic display system described in the above embodiments, the present invention also proposes a computer-generated holographic display method applied to the computer-generated holographic display system.

[0090] Specifically, Figure 4 FIG. 1 is a flow chart showing a method for displaying computer-generated holograms according to an embodiment of the present invention. Figure 4 As shown, the method includes steps S410-S440, and steps S410-S440 and related steps will be described in detail below.

[0091] S410: Acquire a target scene image with a first resolution.

[0092] The target scene image includes the amplitude information or complex amplitude information of the light wave. The amplitude information represents the maximum intensity or brightness of the light wave, which is usually proportional to the light intensity. The complex amplitude information includes the amplitude and phase information of the light wave.

[0093] The target scene image can be acquired based on real camera acquisition or can be obtained by computer rendering, which is not specifically limited here. Among them, the rendering algorithm used by computer rendering can be selected from ray tracing algorithm, path tracing algorithm, artificial intelligence generation algorithm, etc.

[0094] In this embodiment, the target scene image of the first resolution is intended to emphasize that the target scene image is a high-resolution image. The specific value of the first resolution, such as 2K resolution, 4K resolution, 5K resolution, 8K resolution, etc., can be determined according to actual needs and is not specifically limited here.

[0095] After acquiring the target scene image of the first resolution in step S410, further, step S420 is performed.

[0096] S420, calculating and encoding the complex amplitude information of the holographic surface based on the target scene image to obtain a hologram sequence.

[0097] It is easy to understand that after obtaining the target scene image based on real camera acquisition or computer rendering, the target scene image can be divided into multiple moments using the "time division multiplexing" calculation method. The second resolution object light image sequence .

[0098] Specifically, the target scene image can be segmented into a sequence of object light images by image block segmentation. Specifically, the size of each image block (object light image) is first determined according to the first resolution and requirements of the target scene image; then the target scene image is segmented into a plurality of ( N ) objective light images to obtain an objective light image sequence; finally, the corresponding sub-images are processed / displayed at different times.

[0099] The first resolution is much higher than the second resolution, which is intended to emphasize that the object light image is a low-resolution image compared to the target scene image.

[0100] It is worth mentioning that due to the persistence of vision of the human eye, multiple rapid modulations in the time domain can achieve an improvement in the resolution of holographic display.

[0101] After obtaining a low-resolution object light image sequence, it is necessary to calculate the complex amplitude information of the holographic surface corresponding to the object light image sequence. This step can be achieved through traditional holographic algorithms or deep learning methods, including but not limited to different methods based on angular spectrum diffraction, Rayleigh Sommerfeld diffraction, Fresnel diffraction, Fraunhofer diffraction, neural network learning, etc.

[0102] Next, the complex amplitude information of the holographic surface corresponding to the object light image sequence is After encoding processing, the hologram sequence can be obtained.

[0103] After obtaining the complex amplitude information of the holographic surface calculated based on the target scene image and encoding it to obtain a hologram sequence in step S420, further, step S430 is performed.

[0104] S430, controlling the spatial light modulator to load the hologram sequence, and modulating the incident light beam according to the hologram sequence to obtain a diffraction image sequence.

[0105] It is easy to understand that first, the spatial light modulator is controlled to load the corresponding hologram at different times, and then a laser with a wavelength suitable for the spatial light modulator (such as a 532nm green laser) is selected to generate a parallel light beam (incident light beam) through a collimating lens to illuminate the surface of the spatial light modulator. The spatial light modulator is placed in the collimated light path so that the incident light is perpendicular to the surface of the spatial light modulator. At the same time, the light reflected or transmitted from the spatial light modulator is collected through a preset lens group to form a diffraction pattern, that is, a diffraction image, thereby obtaining a diffraction image sequence.

[0106] After the diffraction image sequence is obtained, step S440 is further performed.

[0107] S440, by controlling the rotation angle of the parallel plate modulation element, the diffraction image sequence is holographically displayed on the image plane according to the target offset.

[0108] It is easy to understand that the diffraction image sequence obtained by the spatial light modulator is as the light beam passes through the parallel plate modulation element. The parallel plate modulation element passes at different times. , respectively controlling their own rotation angles to , to achieve the target offset corresponding to the diffraction image sequence , corresponding to the content / image displayed on the image plane , in order to realize time-division multiplexed holographic scanning super-resolution display.

[0109] In a specific embodiment, the target offset can be calculated based on multiple key element parameters of the parallel plate modulation element, as shown in the above formula (6). The multiple key element parameters include refractive index, thickness and rotation angle.

[0110] In another specific embodiment, the target offset can be calculated based on the pixels of the spatial light modulator and the number of diffraction images in the diffraction image sequence.

[0111] In this embodiment, by acquiring a target scene image of a first resolution, the complex amplitude information of the hologram is calculated and encoded based on the target scene image to obtain a hologram sequence, and then the spatial light modulator is controlled to load the hologram sequence, and the incident light beam is modulated according to the hologram sequence to obtain a diffraction image sequence, thereby, by controlling the rotation angle of the parallel plate modulation element, the diffraction image sequence is holographically displayed on the image plane according to the target offset. This method introduces a parallel plate modulation element between the spatial light modulator and the image plane according to the display resolution improvement requirements, and ensures the higher resolution mapping of the lower resolution hologram on the object plane through complex amplitude data compensation, thereby improving the modulation capability of the hologram for the limited resolution spatial light modulator, achieving higher resolution computational holographic display performance, and does not require complex processes and long-term preparation, greatly reducing the cost of holographic super-resolution display.

[0112] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0113] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A computer generated holographic display system, characterized in that: include: A control element, used to obtain a target scene image of a first resolution, calculate and encode the complex amplitude information of the holographic surface based on the target scene image, and obtain a hologram sequence; a spatial light modulator, connected to the control element, for loading the hologram sequence and modulating the incident light beam according to the hologram sequence to obtain a diffraction image sequence; The parallel flat plate modulation element is connected to the spatial light modulator and is used to holographically display the diffraction image sequence on the image plane according to the target offset by controlling its own rotation angle.

2. The computer generated holographic display system according to claim 1, characterized in that: The control element is specifically used to divide the target scene image into an object light image sequence of a second resolution; calculate and encode the complex amplitude information of the holographic surface corresponding to the object light image sequence to obtain a global transmittance function sequence; Among them, the first resolution is higher than the second resolution, and the global transmittance function sequence is the hologram sequence.

3. The computer generated holographic display system according to claim 1, characterized in that: The target offset is calculated based on a plurality of key element parameters of the parallel plate modulation element; The multiple key component parameters include refractive index, thickness and rotation angle.

4. The computer generated holographic display system according to claim 1, characterized in that: The target offset is calculated based on the pixels of the spatial light modulator and the number of diffraction images in a diffraction image sequence.

5. The computer generated holographic display system according to claim 2, characterized in that: The relationship between the target scene image of the first resolution and the object light image sequence of the second resolution is as follows: ； in, represents the target scene image, Indicates the first resolution, Indicates the number of pixels in the horizontal direction. Indicates the number of pixels in the vertical direction. represents the object light image sequence, Indicates the second resolution, Indicates the number of object light images in the object light image sequence.

6. The computer generated holographic display system according to claim 3, characterized in that: The target offset is calculated as follows: ； in, Indicates The target offset of the diffraction image, represents the thickness of the parallel plate modulation element, Indicates The rotation angle corresponding to the diffraction image is, represents the refractive index of the parallel-plate modulation element.

7. The computer generated holographic display system according to claim 2, characterized in that: The calculation formula of the complex amplitude information of the holographic surface corresponding to the object light image sequence is as follows: ； ； in, Indicates the first The complex amplitude information of the holographic surface corresponding to the object light image, represents the Fourier transform, represents the inverse Fourier transform, Indicates An object light image, represents the holographic surface angle spectrum diffraction transfer function, represents the imaginary unit, represents the wave number, represents the diffraction propagation distance, represents the wavelength, , Represent the sampling frequency in the horizontal and vertical directions respectively.

8. A computer generated holographic display method, applied to the computer generated holographic display system according to any one of claims 1 to 7, characterized in that: include: Acquire a target scene image of a first resolution; Calculate the complex amplitude information of the holographic surface based on the target scene image and encode it to obtain a hologram sequence; Controlling a spatial light modulator to load the hologram sequence, and modulating an incident light beam according to the hologram sequence to obtain a diffraction image sequence; By controlling the rotation angle of the parallel flat plate modulation element, the diffraction image sequence is holographically displayed on the image plane according to the target offset.

9. The computer generated holographic display method according to claim 8, characterized in that: The step of calculating the complex amplitude information of the holographic surface based on the target scene image and encoding the information to obtain a hologram sequence comprises: Segmenting the target scene image into a sequence of object light images at a second resolution; Calculating the complex amplitude information of the holographic surface corresponding to the object light image sequence; Encoding the complex amplitude information of the holographic surface corresponding to the object light image sequence to obtain a global transmittance function sequence; Among them, the first resolution is higher than the second resolution, and the global transmittance function sequence is the hologram sequence.

10. The computer generated holographic display method according to claim 8, characterized in that: The target offset is calculated based on a plurality of key element parameters of the parallel plate modulation element, wherein the plurality of key element parameters include a refractive index, a thickness, and a rotation angle; or, The target offset is calculated based on the pixels of the spatial light modulator and the number of diffraction images in a diffraction image sequence.

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