Color hologram optical reproduction method and system based on conjugate diffraction order

Abstract

The invention discloses a color hologram optical reproduction method and system based on conjugate diffraction orders, and relates to the technical field of light modulation.The method comprises the steps that firstly, color holographic data bearing phase and amplitude information of a three-dimensional object is obtained through a computer data transmission interface; loading the color holographic data on the spatial light modulator; then light beams emitted by the laser light sources of various colors are irradiated to the surface of the spatial light modulator after being expanded and collimated, and holograms of corresponding colors are generated; different from the traditional means of selecting the same diffraction order in the prior art, the holograms of all colors are synthesized into the high-fidelity color hologram by aligning the conjugate diffraction orders of the laser light sources of all colors. According to the scheme, the number of complex optical elements can be reduced, the cost and the experiment operation difficulty are reduced, and meanwhile interference fringes and optical loss existing in the dichroscope set can be avoided.

Description

Technical Field

[0001] The present application relates to the field of optical modulation technology, and particularly to an optical reproduction method and system for a color hologram based on conjugate diffraction orders. Background Art

[0002] Holographic display technology, as the ultimate form in the field of three-dimensional display, its core challenge lies in achieving high-fidelity, full-color, and dynamically adjustable image reproduction. Currently, this technology generally uses a spatial light modulator (SLM) to load a computer-generated hologram (CGH), and realizes color display through the beam combination of multi-wavelength lasers. However, in practical applications, the following technical bottlenecks are still faced: The traditional method uses the same diffraction order (such as the +1 order) of red, green, and blue lasers for beam combination, and relies on a dichroic mirror group to realize optical path coupling. This method has two major defects: First, the splitting loss is serious, and the transmission loss of a single dichroic mirror exceeds 10%, resulting in a total energy loss of up to 32.1% in the three-color beam combination system; Second, there is a problem of spatial dispersion accumulation. Due to the wavelength difference of the three-color light (Δλ = 188nm), at a working distance of 500mm, the diffraction angle deviation reaches 1.2°, and an additional prism compensation system is required, which increases the complexity of the optical path.

[0003] Therefore, it is particularly important to solve the systematic problems of complex optical path and low efficiency in the traditional solution, and provide a physical layer solution for the industrialization of holographic display technology. Summary of the Invention

[0004] The purpose of the present application is to provide an optical reproduction method and system for a color hologram based on conjugate diffraction orders, which can reduce the cost of the optical path system and effectively avoid the interference fringes and optical losses existing in the use of a dichroic mirror group.

[0005] To achieve the above purpose, the present application provides the following solutions:

[0006] In a first aspect, the present application provides an optical reproduction method for a color hologram based on conjugate diffraction orders, including:

[0007] Obtain the color holographic data of a three-dimensional object through a computer data transmission interface, and load the color holographic data on a spatial light modulator; the color holographic data carries the phase and amplitude information of the three-dimensional object.

[0008] After expanding and collimating the beams emitted by each color laser light source, irradiate them on the surface of the spatial light modulator to generate a hologram of the corresponding color; the color laser light source includes a red laser light source, a blue laser light source, and a green laser light source.

[0009] By aligning the conjugate diffraction orders of the laser light sources of various colors, the holograms of each color are synthesized into a color hologram; the conjugate diffraction orders are two diffraction orders with symmetric distribution on both sides of the normal of the grating and equal light intensity.

[0010] Optionally, by aligning the conjugate diffraction orders of the laser light sources of various colors, the holograms of each color are synthesized into a color hologram, which specifically includes the following steps:

[0011] Select a suitable common diffraction angle for the laser light sources of various colors so that the diffraction orders of the laser light sources of various colors are in a horizontally propagating state.

[0012] According to the grating diffraction equation, calculate the beam incident angle of the laser light sources of various colors.

[0013] According to the spatial position relationship between the laser light sources of various colors and the spatial light modulator, calculate the height of the laser light sources of various colors.

[0014] Adjust the optical path according to the height and beam incident angle of the laser light sources of various colors, align the conjugate diffraction orders of the laser light sources of various colors, and synthesize the holograms of each color into a color hologram.

[0015] Optionally, the grating diffraction equation is shown as follows:

[0016] d·(sinθ m -sinθ incident )=mλ.

[0017] Wherein, d is the grating period on the surface of the spatial light modulator, θ m is the diffraction angle of the m-th order, θ incident is the beam incident angle, m is the diffraction order, and λ is the wavelength of the laser light source.

[0018] Optionally, a single grating on the surface of the spatial light modulator is not sufficient to fully represent the required phase or amplitude information. Every several gratings on the surface of the spatial light modulator form a modulation unit. At this time, according to the modified grating diffraction equation, calculate the beam incident angle of the laser light sources of various colors; the modified grating diffraction equation is an equation obtained by modifying the traditional grating diffraction equation according to the effective period of the gratings on the surface of the spatial light modulator.

[0019] Optionally, the modified grating diffraction equation is shown as follows:

[0020] Kd·(sinθ m -sinθ incident )=mλ.

[0021] Wherein, K is the number of rows / columns of the gratings in a single modulation unit on the surface of the spatial light modulator, d is the grating period on the surface of the spatial light modulator, θ m is the diffraction angle of the m-th order, θincident is the incident angle of the light beam, m is the diffraction order, and λ is the wavelength of the laser light source.

[0022] Optionally, the sine value of the incident angle of the light beam of each color laser light source is calculated according to the following formula:

[0023]

[0024] where c represents the diffraction of the laser light source, r, g, and b represent red, green, and blue respectively; θ incident,c is the incident angle of the light beam of the c-color laser light source, and λ c is the wavelength of the c-color laser light source.

[0025] The incident angle of the light beam of the c-color laser light source is calculated according to the following formula:

[0026] θ incident,c = arcsin(sinθ incident,c ), c ∈ {r, g, b}.

[0027] where arcsin() is the arcsine function.

[0028] Optionally, for the red laser light source and the blue laser light source, the -1 diffraction order in the y-axis direction is selected, and for the green laser light source, the +1 diffraction order in the y-axis direction is selected; when the diffraction angle of the diffraction order corresponding to each color laser light source is 0, the diffraction orders of each color laser light source are all in a horizontal propagation state.

[0029] Optionally, the height of each color laser light source is calculated according to the following formula:

[0030] h c = H SLM ± L·tan(θ incident,c ).

[0031] where h c is the height of the c-color laser light source, H SLM is the height of the center position of the spatial light modulator, L is the distance from the laser light source to the spatial light modulator, and θ incident,c is the incident angle of the light beam of the c-color laser light source.

[0032] In a second aspect, the present application provides a color hologram optical reproduction system based on conjugate diffraction orders, including:

[0033] A color holographic data loading module, configured to obtain color holographic data of a three-dimensional object through a computer data transmission interface and load the color holographic data on a spatial light modulator; the color holographic data carries phase and amplitude information of the three-dimensional object.

[0034] The laser light source beam expanding and collimating module is used to expand and collimate the beams emitted by various laser light sources and then irradiate them onto the surface of the spatial light modulator to generate holograms of corresponding colors; the color laser light sources include a red laser light source, a blue laser light source, and a green laser light source.

[0035] The conjugate diffraction order alignment module is used to synthesize holograms of various colors into a color hologram by aligning the conjugate diffraction orders of various laser light sources; the conjugate diffraction orders are two diffraction orders with symmetric distribution on both sides of the normal of the grating and equal light intensity.

[0036] Optionally, the conjugate diffraction order alignment module includes:

[0037] The common diffraction angle determination unit is used to select a suitable common diffraction angle for various laser light sources so that the diffraction orders of various laser light sources are in a horizontally propagating state.

[0038] The beam incident angle calculation unit is used to calculate the beam incident angles of various laser light sources according to the grating diffraction equation.

[0039] The laser light source height calculation unit is used to calculate the heights of various laser light sources according to the spatial position relationship between various laser light sources and the spatial light modulator.

[0040] The conjugate diffraction order alignment unit is used to adjust the optical path according to the heights and beam incident angles of various laser light sources to align the conjugate diffraction orders of various laser light sources so that holograms of various colors are synthesized into a color hologram.

[0041] According to the specific embodiments provided in this application, the following technical effects are disclosed in this application:

[0042] The present application provides an optical reproduction method and system for a color hologram based on conjugate diffraction orders. In this method, color holographic data carrying the phase and amplitude information of a three-dimensional object is obtained through a computer data transmission interface, and the color holographic data is loaded onto a spatial light modulator. Subsequently, the light beams emitted by a red laser light source, a blue laser light source, and a green laser light source are expanded and collimated and then irradiated onto the surface of the spatial light modulator to generate holograms of corresponding colors. Different from the conventional means of selecting the same diffraction order in the prior art, in the present application, by aligning the conjugate diffraction orders of the respective color laser light sources, the holograms of each color are synthesized into a high-fidelity color hologram. In the present application, by selecting the conjugate diffraction orders for the respective color laser light sources, the incident angles of the respective color laser light sources can be increased to avoid beam occlusion, and no complex beam splitting elements are required. Compared with the means of using a dichroic mirror group in the optical path system when selecting the same diffraction order in the prior art, only one dichroic mirror needs to be retained in the present application, and other dichroic mirrors can be replaced with ordinary reflectors, reducing the number of complex optical elements, lowering the cost, making the adjustment of the optical path system more flexible, reducing the experimental operation difficulty, and effectively avoiding the interference fringes and light loss existing in the dichroic mirror group. Description of the Drawings

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0044] Figure 1 It is a flowchart of an optical reproduction method for a color hologram based on conjugate diffraction orders provided by an embodiment of the present application.

[0045] Figure 2 It is a schematic diagram of multi-level diffraction spots formed when an incident light wave passes through the surface of a spatial light modulator SLM.

[0046] Figure 3 It is a partial optical path schematic diagram of selecting conjugate diffraction orders in an optical reproduction method for a color hologram based on conjugate diffraction orders provided by an embodiment of the present application.

[0047] Figure 4 It is a partial optical path schematic diagram of selecting the same diffraction order in the prior art.

[0048] Figure 5 It is a structural schematic diagram of an optical path system in an optical reproduction method for a color hologram based on conjugate diffraction orders provided by an embodiment of the present application.

[0049] Figure 6Schematic diagram of the functional modules of a color hologram optical reconstruction system based on conjugate diffraction orders provided by an embodiment of the present application.

[0050] Figure 7 Schematic diagram of the structure of a computer device provided by an embodiment of the present application. Detailed implementation manners

[0051] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0052] In the reconstruction process of computer-generated holograms (CGHs), the core technology is to precisely control light waves using a spatial light modulator (SLM). First, the three-dimensional information of an object is converted into CGH data through specific algorithms. Commonly used algorithms include the point source method, the angular spectrum method, and the Fresnel diffraction method. The input data is a three-dimensional object model and light source information, and the output is a complex value matrix of key information such as the phase and amplitude of the three-dimensional object. Subsequently, the computer efficiently and accurately loads the generated CGH data onto a high-resolution spatial light modulator SLM through a data transmission interface. The spatial light modulator SLM, as a key optical element, consists of a regularly arranged grating array, and each grating has the ability to independently modulate the phase or amplitude of the incident light wave. When a beam of light emitted by a precisely expanded and collimated laser light source irradiates the surface of the SLM loaded with CGH data, the SLM will finely modulate the phase and amplitude of the incident light wave according to the loaded color holographic data. Through this modulation, the information carried by the incident light wave is re-encoded, thus laying a foundation for the subsequent high-quality reconstruction of the three-dimensional object holographic image through the optical system. Throughout this process, the SLM plays a bridging role, converting the digital CGH data generated by the computer into optical signals that can be processed in the optical field, which is the core link for realizing the reconstruction of holographic images.

[0053] In the prior art, a spatial light modulator (SLM) is generally used to load computer-generated CGH data, and multi-wavelength lasers are combined through a co-directional diffraction order scheme to achieve color display. However, the following technical bottlenecks still exist in practical applications: Since the prior art uses the same diffraction order (such as the +1 order) to combine red, green, and blue lasers, this requires a dichroic mirror group to achieve optical path coupling. However, due to the transmission loss of a single dichroic mirror > 10%, the total energy loss of the three-color beam combining system is as high as 32.1%, resulting in serious spectral loss in the optical path system. In addition, due to the wavelength difference of the three-color light (Δλ = 188 nm), a diffraction angle deviation (Δθ = 1.2° @ 500 mm working distance) occurs, and a prism compensation system needs to be added, increasing the complexity of the optical path and causing spatial dispersion accumulation.

[0054] Based on the above analysis of the prior art, the present application proposes the conjugate diffraction order multiplexing theory: By selecting the -1 order of red / blue light and the +1 order of green light diffraction, the self-alignment beam combination of the three-color light is realized by using its spatial symmetry. This concept stems from two key discoveries: The reversibility of the incident angle of the grating equation: When the conjugate diffraction order m takes ±1, sinθ is linearly inversely proportional to the wavelength λ, and the diffraction angle offset caused by the wavelength difference can be compensated by adjusting the incident angle; The efficiency advantage of the reflective optical path: The average reflectivity of a metal mirror (Al / MgF2 coating) in the 450 - 650 nm band is > 98%, which improves the energy utilization rate by 15% compared with the dichroic mirror scheme.

[0055] The proposal of this technical idea in the present application successfully solves systematic problems such as complex optical path and low efficiency in the traditional scheme, and provides a physical layer solution for the industrialization of holographic display technology.

[0056] To make the above objects, features, and advantages of the present application more obvious and understandable, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0057] The method for optically reconstructing a color hologram based on conjugate diffraction orders provided by the embodiments of the present application, in an exemplary embodiment, as Figure 1 shown, includes the following steps:

[0058] A1. Obtain the color holographic data of a three-dimensional object through a computer data transmission interface, and load the color holographic data on a spatial light modulator; the color holographic data carries the phase and amplitude information of the three-dimensional object.

[0059] A2. After expanding and collimating the beams emitted by each color laser light source, irradiate them on the surface of the spatial light modulator to generate a hologram of the corresponding color; the color laser light source includes a red laser light source, a blue laser light source, and a green laser light source.

[0060] The surface of the spatial light modulator (SLM) consists of a regularly arranged grating array. These gratings can independently modulate the phase or amplitude of the incident light wave and have periodic characteristics. Essentially, the SLM is a two-dimensional grating composed of a pixel array. When the incident light wave passes through this periodic structure, complex diffraction phenomena occur, forming multiple diffraction spots (such as ±1 order, ±2 order, etc.), as Figure 2 shown. The grating diffraction equation is:

[0061] d·(sinθ m -sinθ incident )=mλ.

[0062] where d is the grating period (pixel pitch), θ m is the diffraction angle of the m-th order, θ incident is the incident angle of the light beam, m is the diffraction order, and λ is the wavelength of the laser light source. By adjusting the wavelength λ, the incident angle θ incident or the pixel period d, the diffraction angle distribution can be controlled.

[0063] A3. By aligning the conjugate diffraction orders of the respective color laser light sources, the holograms of each color are synthesized into a color hologram; the conjugate diffraction orders are two diffraction orders with symmetric distribution of the diffraction angles on both sides of the normal of the grating and equal light intensities. Specifically, the following characteristics exist between a pair of conjugate diffraction orders, which can be understood from physical laws and the grating diffraction formula:

[0064] 1. Have symmetric diffraction angles:

[0065] For two conjugate diffractions (such as +m and -m), their diffraction orders m and -m are opposite, and the incident angle θ incident is the same. Therefore, the sine values of the diffraction angles θ +m and θ -m satisfy: sinθ +m =-sinθ -m . This means that the diffraction angles of the conjugate diffraction orders are symmetrically distributed on both sides of the normal of the grating (i.e., the vertical direction).

[0066] 2. Have equal light intensity distributions:

[0067] In an ideal case (assuming the grating is uniform and defect-free), the light intensities of the conjugate diffraction orders (such as +m and -m) are equal. This is because: the periodic structure of the grating causes the diffraction of light to have symmetry, and the energy distribution of the light wave is uniform in the positive and negative diffraction orders. As Figure 2 can be seen, the brightness of +1 and -1 orders, +2 and -2 orders, etc. is symmetric, indicating that their light intensities are equal.

[0068] In this embodiment, step A3 specifically includes the following steps:

[0069] A31. Select appropriate common diffraction angles for each color laser source so that the diffraction orders of each color laser source are in a horizontally propagating state. In this embodiment, for the red laser source and the blue laser source, the -1 diffraction order in the y-axis direction is selected, and for the green laser source, the +1 diffraction order in the y-axis direction is selected; when the diffraction angles of the diffraction orders corresponding to each color laser source are 0, the diffraction orders of each color laser source are all in a horizontally propagating state.

[0070] Specifically, usually let θ m = 0. This setting can make the diffraction orders corresponding to the selected three-color lasers all in a horizontally propagating state, which is convenient for subsequent unified analysis and adjustment of the optical path, can simplify the optical path design and calculation process, and provides convenient conditions for achieving precise alignment of the three-color light. As Figure 3 shown, in the solution of this application, the red laser and the green laser enter the spatial light modulator through a mirror, while the blue laser enters the spatial light modulator through a dichroic mirror, and the optical paths do not block each other; in the traditional holographic reproduction technology using the same diffraction order, as Figure 4 shown, the blue laser, the green laser, and the red laser need to pass through a dichroic mirror group composed of 2 dichroic mirrors and 1 mirror. The 2 dichroic mirrors among them block the optical paths of other lasers, resulting in serious spectral splitting loss and spatial dispersion accumulation problems.

[0071] A32. According to the grating diffraction equation, calculate the beam incident angles of each color laser source. Specifically, the grating diffraction equation mentioned in step A32 is shown as follows:

[0072] d·(sinθ m -sinθ incident ) = mλ.

[0073] Among them, d is the grating period on the surface of the spatial light modulator, θ m is the diffraction angle of the m-th order, θ incident is the beam incident angle, m is the diffraction order, and λ is the wavelength of the laser source.

[0074] In addition, a single grating on the surface of the spatial light modulator is usually not sufficient to fully represent the required phase or amplitude information. Therefore, multiple gratings are often combined together to form a larger and functionally complete modulation unit. This combination may be a 2×2, 3×3 or larger grating array. When multiple gratings are combined into a modulation unit, the effective period of the grating changes. If K 2 gratings form a unit, then the new effective period is no longer the spacing d of a single grating, but becomes Kd. Based on this new period structure, the traditional grating diffraction equation needs to be adjusted accordingly.

[0075] In a specific embodiment of the present application, a single grating on the surface of the spatial light modulator is not sufficient to fully represent the required phase or amplitude information. Every several gratings on the surface of the spatial light modulator form a modulation unit. At this time, according to the modified grating diffraction equation, the beam incident angle of each color laser light source is calculated; the modified grating diffraction equation is obtained by modifying the traditional grating diffraction equation according to the effective period of the grating on the surface of the spatial light modulator. Specifically, the modified grating diffraction equation is shown as follows:

[0076] Kd·(sinθ m -sinθ incident )=mλ。

[0077] Wherein, K is the number of rows / columns of the gratings in a single modulation unit on the surface of the spatial light modulator, d is the grating period on the surface of the spatial light modulator, θ m is the diffraction angle of the m-th order, θ incident is the beam incident angle, m is the diffraction order, and λ is the wavelength of the laser light source.

[0078] When specifically applying the above modified grating diffraction equation, the sine value of the beam incident angle of each color laser light source can be calculated according to the following formula:

[0079]

[0080] Wherein, c represents the diffraction of the laser light source, and r, g, and b represent red, green, and blue respectively; θ incident,c is the beam incident angle of the c-color laser light source, and λ c is the wavelength of the c-color laser light source.

[0081] The beam incident angle of the c-color laser light source is calculated according to the following formula:

[0082] θ incident,c =arcsin(sinθ incident,c ), c ∈ {r, g, b}.

[0083] Wherein, arcsin() is the arcsine function.

[0084] A33. According to the spatial position relationship between each color laser light source and the spatial light modulator, calculate the height of each color laser light source. Specifically, in this embodiment, the height of each color laser light source can be calculated according to the following formula:

[0085] h c =H SLM ±L·tan(θ incident,c ).

[0086] Wherein, h c is the height of the c-color laser light source, and H SLMis the height of the center position of the spatial light modulator, L is the distance from the laser light source to the spatial light modulator, and θ incident,c is the beam incident angle of the c-color laser light source. From this, the height position that each color light source should be in the optical system can be calculated.

[0087] A34. Adjust the optical path according to the height and beam incident angle of each color laser light source, align the conjugate diffraction orders of each color laser light source, so that the holograms of each color are synthesized into a color hologram.

[0088] The reproduction of the three-dimensional object color hologram in the above application of this application requires complex optical settings. Usually, laser sources with three wavelengths of red (638nm), green (520nm), and blue (450nm) are used, as well as corresponding three-color CGH data. The spatial light modulator SLM loads these three CGHs in sequence, and then irradiates them with lasers of corresponding wavelengths respectively to generate red, green, and blue three-color holograms. Its optical path system is as Figure 5 shown. After the laser, there are some lenses and polarizers. The polarizer is used to expand the laser beam passing through, and the lens collimates it again. After the red laser and the green laser each pass through a mirror and are synthesized with the blue light passing through a dichroic mirror, they are reflected by the beam splitter to the spatial light modulator. The formed holographic image passes through the beam splitter and the corresponding filtering device, and then is captured by the camera or the human eye; through precise spatial and temporal multiplexing technology, these three-color holograms are synthesized to finally obtain a high-fidelity color holographic image.

[0089] The reason for choosing the conjugate diffraction order rather than the same diffraction order in this application mainly focuses on the optimization of the experimental optical path design and the convenience of actual operation. The following are the specific reasons:

[0090] (1) Simplify the optical path design: The conjugate order increases the incident angles of the three-color light (RGB), avoids beam occlusion, and does not require complex beam splitting elements.

[0091] (2) Reduce costs and complexity: Replace the dichroic mirror with an ordinary mirror, reduce the number of optical elements, reduce costs, and avoid the interference fringes and light loss of the dichroic mirror at the same time.

[0092] (3) Improve the light intensity efficiency: The reflection efficiency of the mirror (≈99%) is higher than that of the dichroic mirror (90%-95%), reduce light loss, and enhance the incident light intensity.

[0093] (4) Operational convenience: The optical path adjustment of the conjugate order is more flexible, reducing the difficulty of experimental operation.

[0094] Based on the same inventive concept, an embodiment of the present application further provides a system for implementing the above-mentioned optical reproduction method of a color hologram based on conjugate diffraction orders. The implementation solutions provided by this system to solve problems are similar to those recorded in the above method. Therefore, the specific limitations in one or more system embodiments provided below can refer to the limitations on the optical reproduction method of the color hologram based on conjugate diffraction orders in the above text, and will not be elaborated here.

[0095] In an exemplary embodiment, as Figure 6 shown, a system for optical reproduction of a color hologram based on conjugate diffraction orders is provided, including:

[0096] A color holographic data loading module, configured to obtain the color holographic data of a three-dimensional object through a computer data transmission interface and load the color holographic data on a spatial light modulator; the color holographic data carries the phase and amplitude information of the three-dimensional object.

[0097] A laser light source beam expanding and collimating module, configured to expand and collimate the beams emitted by each color laser light source and then irradiate them on the surface of the spatial light modulator to generate holograms of corresponding colors; the color laser light sources include a red laser light source, a blue laser light source, and a green laser light source.

[0098] A conjugate diffraction order alignment module, configured to synthesize the holograms of each color into a color hologram by aligning the conjugate diffraction orders of each color laser light source; the conjugate diffraction orders are two diffraction orders with symmetric distribution on both sides of the normal of the grating and equal light intensity.

[0099] Specifically in this embodiment, the conjugate diffraction order alignment module includes:

[0100] A common diffraction angle determination unit, configured to select a suitable common diffraction angle for each color laser light source so that the diffraction orders of each color laser light source are in a horizontally propagating state.

[0101] A beam incident angle calculation unit, configured to calculate the beam incident angles of each color laser light source according to the grating diffraction equation.

[0102] A laser light source height calculation unit, configured to calculate the heights of each color laser light source according to the spatial position relationship between each color laser light source and the spatial light modulator.

[0103] A conjugate diffraction order alignment unit, configured to adjust the optical path according to the heights and beam incident angles of each color laser light source to align the conjugate diffraction orders of each color laser light source so that the holograms of each color are synthesized into a color hologram.

[0104] Of course, Figure 6 the architecture shown is only exemplary. When implementing different functions, according to actual needs, it can be omittedFigure 6 One or at least two components in the illustrated system.

[0105] In an exemplary embodiment, a computer device is provided. The computer device can be a server or a terminal, and its internal structure diagram can be as Figure 7 shown. The computer device includes a processor, a memory, an input / output interface (Input / Output, abbreviated as I / O), and a communication interface. Among them, the processor, the memory, and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The input / output interface of the computer device is used to exchange information between the processor and external devices. The communication interface of the computer device is used to communicate with external terminals through a network connection. When the computer program is executed by the processor, it can implement a method for optical reproduction of a color hologram based on conjugate diffraction orders provided in the above embodiments.

[0106] Those skilled in the art can understand that Figure 7 the structure shown in

[0107] is only a block diagram of some structures related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine some components, or have a different component layout.

[0108] In an exemplary embodiment, a computer device is further provided, including a memory and a processor. A computer program is stored in the memory, and when the processor executes the computer program, the steps in the above method embodiments are implemented.

[0109] In an exemplary embodiment, a computer-readable storage medium is provided, storing a computer program, and when the computer program is executed by the processor, the steps in the above method embodiments are implemented.

[0110] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use, and processing of relevant data need to comply with relevant regulations.

[0111] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, database, or other medium used in the embodiments provided in this application can include at least one of non-volatile and volatile memories. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc.

[0112] The databases involved in the embodiments provided in this application can include at least one of relational databases and non-relational databases. Non-relational databases can include distributed databases based on blockchain, etc., and are not limited thereto. The processors involved in the embodiments provided in this application can be general-purpose processors, central processors, graphics processors, digital signal processors, programmable logic devices, data processing logics based on quantum computing, etc., and are not limited thereto.

[0113] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered to be within the scope described in this specification.

[0114] In this article, specific examples are used to elaborate on the principles and implementation manners of the present application. The descriptions of the above embodiments are only used to help understand the method and its core idea of the present application; at the same time, for those of ordinary skill in the art, according to the idea of the present application, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A method for optically reproducing a color hologram based on conjugate diffraction orders, characterized in that: include: Acquire color holographic data of a three-dimensional object through a computer data transmission interface, and load the color holographic data onto a spatial light modulator; the color holographic data carries phase and amplitude information of the three-dimensional object; After beam expansion and collimation, the light beams emitted by the laser light sources of each color are irradiated onto the surface of the spatial light modulator to generate a hologram of the corresponding color; the color laser light sources include a red laser light source, a blue laser light source and a green laser light source; By aligning the conjugate diffraction orders of laser light sources of different colors, holograms of different colors are synthesized into a color hologram; the conjugate diffraction orders are two diffraction orders with symmetrical diffraction angles on both sides of the normal line of the grating and equal light intensity.

2. The method for optically reproducing a color hologram based on conjugate diffraction orders according to claim 1, characterized in that: By aligning the conjugate diffraction orders of the laser light sources of each color, the holograms of each color are synthesized into a color hologram, specifically including: Selecting a suitable common diffraction angle for each color laser light source so that the diffraction order of each color laser light source is in a horizontal propagation state; According to the grating diffraction equation, calculate the incident angle of the beam of each color laser light source; Calculating the height of each color laser light source according to the spatial position relationship between each color laser light source and the spatial light modulator; The optical path is adjusted according to the height of each color laser light source and the incident angle of the light beam, and the conjugate diffraction orders of each color laser light source are aligned, so that the holograms of each color are synthesized into a color hologram.

3. The method for optically reproducing a color hologram based on conjugate diffraction orders according to claim 2, characterized in that: The grating diffraction equation is shown below: d·(sinθ m -sinθ incident )=mλ; Where d is the grating period on the surface of the spatial light modulator, θ m is the diffraction angle of the mth order, θ incident is the incident angle of the light beam, m is the diffraction order, and λ is the wavelength of the laser light source.

4. The method for optically reproducing a color hologram based on conjugate diffraction orders according to claim 2, characterized in that: A single grating on the surface of the spatial light modulator is not sufficient to fully represent the required phase or amplitude information. Every several gratings on the surface of the spatial light modulator form a modulation unit. At this time, the incident angle of the light beam of each color laser light source is calculated according to the modified grating diffraction equation; the modified grating diffraction equation is an equation obtained by correcting the traditional grating diffraction equation according to the effective period of the grating on the surface of the spatial light modulator.

5. The method for optically reproducing a color hologram based on conjugate diffraction orders according to claim 4, characterized in that: The corrected grating diffraction equation is shown as follows: Kd·(sinθ m -sinθ incident )=mλ; Where K is the number of rows / columns of the grating in a single modulation unit on the surface of the spatial light modulator, d is the grating period on the surface of the spatial light modulator, and θ m is the diffraction angle of the mth order, θ incident is the incident angle of the light beam, m is the diffraction order, and λ is the wavelength of the laser light source.

6. The method for optically reproducing a color hologram based on conjugate diffraction orders according to claim 5, characterized in that: The sine value of the incident angle of the beam of each color laser light source is calculated according to the following formula: Where c represents the diffraction of the laser light source, r, g and b represent red, green and blue respectively; θ incident,c is the incident angle of the c-color laser light source, λ c is the wavelength of the c-color laser light source; The incident angle of the beam of the C-color laser light source is calculated according to the following formula: i incident,c =arcsin(sinθ) incident,c ),c∈{r,g,b}; Among them, arcsin() is the inverse sine function.

7. The method for optically reproducing a color hologram based on conjugate diffraction orders according to any one of claims 2 to 6, characterized in that: For the red laser light source and the blue laser light source, the -1 diffraction order in the y-axis direction is selected, and for the green laser light source, the +1 diffraction order in the y-axis direction is selected; when the diffraction angle corresponding to the diffraction order of each color laser light source is 0, the diffraction order of each color laser light source is in a horizontal propagation state.

8. The method for optically reproducing a color hologram based on conjugate diffraction orders according to any one of claims 2 to 6, characterized in that: The height of each color laser light source is calculated according to the following formula: h c =H SLM ±L·time(θ incident,c ); Among them, h c is the height of the c-color laser light source, H SLM is the height of the center position of the spatial light modulator, L is the distance from the laser light source to the spatial light modulator, θ incident,c is the incident angle of the light beam of the c-color laser light source.

9. A color hologram optical reconstruction system based on conjugate diffraction orders, characterized in that: include: A color holographic data loading module is used to obtain color holographic data of a three-dimensional object through a computer data transmission interface, and load the color holographic data onto a spatial light modulator; the color holographic data carries phase and amplitude information of the three-dimensional object; A laser light source beam expansion and collimation module is used to expand and collimate the light beams emitted by the laser light sources of each color and then irradiate them onto the surface of the spatial light modulator to generate a hologram of the corresponding color; the color laser light sources include a red laser light source, a blue laser light source and a green laser light source; The conjugate diffraction order alignment module is used to align the conjugate diffraction orders of laser light sources of different colors so that the holograms of different colors are synthesized into a color hologram; the conjugate diffraction orders are two diffraction orders with equal light intensity and symmetrical diffraction angles on both sides of the normal line of the grating.

10. The color hologram optical reconstruction system based on conjugate diffraction orders according to claim 9, characterized in that: The conjugate diffraction order alignment module comprises: A common diffraction angle determination unit, used to select a suitable common diffraction angle for each color laser light source, so that the diffraction order of each color laser light source is in a horizontal propagation state; A beam incident angle calculation unit, used to calculate the beam incident angles of the laser light sources of various colors according to the grating diffraction equation; A laser light source height calculation unit, used to calculate the height of each color laser light source according to the spatial position relationship between each color laser light source and the spatial light modulator; The conjugate diffraction order alignment unit is used to adjust the optical path according to the height of each color laser light source and the incident angle of the light beam, and align the conjugate diffraction orders of each color laser light source so that the holograms of each color are synthesized into a color hologram.

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