Real-time holographic acquisition and reconstruction of real scenes

Abstract

A real scene real-time holographic acquisition and reproduction system and method, the system comprises a light source module, a computing control module, an imaging device, a light guide device; when performing holographic acquisition, the infrared light source emits illumination light, which is conducted by the light guide device and irradiates to the object in the real scene to be holographically acquired and is reflected, the reflected light carrying the object information is captured by the infrared imaging module; using a spatial light modulator, the imaging module respectively captures two object reflected lights propagating different distances in turn; based on the light intensity transmission equation, the object complex amplitude is solved and hologram encoding is performed through the intensity of the two captured times, and holographic acquisition is completed; when performing holographic display, the illumination light emitted by the visible light source is irradiated to the spatial light modulator loaded with the encoded hologram through the light guide device, and the holographic three-dimensional image of the object is reconstructed. The holographic acquisition and holographic display are alternately performed in time sequence, and real-time holographic acquisition and display are realized.

Description

Technical Field

[0001] The present invention belongs to the field of holographic technology. Specifically, the present invention relates to a real-time holographic acquisition and reproduction system and method for real scenes. Background Art

[0002] Since its invention in the 1940s, holographic technology has been considered the most promising technology in the field of 3D display. Holographic technology provides the human eye with complete optical information, ensuring comfortable focus adjustment and seamless parallax cues. Holographic technology involves two processes: holographic acquisition and holographic display. These processes are often separate, and there is virtually no technology that can simultaneously perform holographic acquisition and display in real time.

[0003] Currently, there are two main methods for holographic acquisition for 3D displays. One method is optical holography, which uses the interference effect between the object beam and the reference beam to record interference fringes containing complete information about the object on a holographic plate. The other is computational holography, which first converts the real object or scene into a 3D model that can be understood by a computer program, and then encodes the 3D model into a hologram. The disadvantages of optical acquisition are that it requires a complex optical path, resulting in poor system portability, and that dynamic acquisition is difficult to achieve. The disadvantage of computational holography is that the intermediate process between the real scene object and the hologram is the 3D model, which makes the acquisition very difficult to achieve in real time.

[0004] For the better application of holographic technology in augmented reality and virtual reality, the holographic acquisition and reproduction of real scenes is essential. A digital holographic system capable of real-time reconstruction is highly desirable. Therefore, in the field of computational holography, there is an urgent need to solve the problem of real-time holographic acquisition and display.

[0005] Patent CN102024272A discloses a device and method for acquiring a three-dimensional computer-generated hologram of a moving object. The device uses a computer-controlled camera to acquire the object's spectral and depth information through a lens array, ultimately encoding the information into a hologram to achieve computer-generated hologram acquisition. However, the device requires 18 images to acquire depth information, and encoding the hologram using depth factors requires complex Fourier transform operations, making real-time acquisition difficult, and, consequently, making it difficult to achieve real-time holographic acquisition and display.

[0006] Patent CN100429587C authorizes a method for recording and displaying holographic stereoscopic images, as well as its device and application. This method uses a camera to continuously capture a scene in a circular motion, generating two-dimensional images from different angles. This two-dimensional image set is then optically converted into a holographic negative, which is ultimately used for holographic display. Theoretically, the three steps of continuously capturing the scene, computer processing the two-dimensional images, and exposing the holographic negative are difficult to complete in a short period of time, making it difficult to achieve real-time holographic acquisition and display. Summary of the Invention

[0007] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a real-time holographic acquisition and reproduction system and method for real scenes. The holographic acquisition device and the holographic display device are integrated into one design, so that the real scene can be holographically reproduced in real time, effectively solving the problem that holographic acquisition and holographic display of real scenes are difficult to carry out in real time.

[0008] The technical solutions of the present invention are as follows:

[0009] A real-time holographic acquisition and reproduction system for real scenes, characterized by:

[0010] an infrared light source module configured to provide collimated infrared light during a holographic acquisition process;

[0011] a visible light source module configured to provide collimated visible light during holographic display;

[0012] A light guiding device, configured as at least two beam splitters, for deflecting, splitting, and guiding a light beam; specifically, during a holographic acquisition process, guiding infrared light emitted by the infrared light source to an object in a real scene, and guiding reflected light from the object to an imaging device via a spatial light modulator; and during a holographic display process, guiding visible light emitted by the visible light source module to the spatial light modulator to generate a holographic image of the object;

[0013] Infrared imaging device, used to capture reflected light with different propagation distances carrying object information during the holographic acquisition process, and generate corresponding intensity maps;

[0014] The computing control module is respectively connected to the infrared light source module, the visible light source module, the light guide device, and the infrared imaging device and controls their working timing. Specifically, the computing control module controls the light emission timing of the infrared light source module and the visible light source module to ensure that the two emit light alternately without overlapping. During the holographic acquisition process, that is, when the infrared light source module is turned on and the visible light source module is turned off, the computing control module controls the infrared imaging device to capture reflected light at at least two different propagation distances and generates at least two corresponding intensity maps, wherein the absolute value of the difference between the second propagation distance and the first propagation distance is the effective propagation distance of the light intensity transmission equation, and by processing and calculating the two intensity maps, a coded hologram carrying object information is obtained; during the holographic display process, that is, when the infrared light source module is turned off and the visible light source module is turned on, the computing control module controls the spatial light modulator to load the coded hologram and generate a holographically reconstructed three-dimensional image of the object.

[0015] Furthermore, the effective propagation distance of the light intensity transmission equation is 1 to 10 microns.

[0016] Preferably, the infrared light source module includes an infrared light source and an infrared collimating lens, the visible light source module includes a visible coherent light source and a visible collimating lens therewith, and the infrared imaging device includes an infrared imaging sensor and an imaging lens; the spatial light modulator is connected to the computing control module, and is used to modulate the object light wave during the holographic acquisition process to change the propagation distance of the light wave; and to load the encoded hologram during the holographic display process to generate a holographic image of the object; wherein, during the holographic acquisition process, the infrared imaging device, with the assistance of the spatial light modulator, successively captures reflected light carrying object information and having different propagation distances, and generates a corresponding intensity map.

[0017] Preferably, the infrared light source module includes an infrared light source and an infrared collimating lens, the visible light source module includes a visible coherent light source and a visible collimating lens, and the infrared imaging device includes at least two groups of infrared imaging sensors and imaging lenses, ensuring that reflected light carrying object information and with different propagation distances is captured during the holographic acquisition process and a corresponding intensity map is generated.

[0018] The infrared imaging device is used to capture infrared light and generate corresponding electrical signals.

[0019] The light guiding device includes at least three beam splitters.

[0020] Preferably, the light guiding device is composed of three beam splitters, and the light guiding device has, in accordance with the propagation direction of light, the following: an infrared light source module light inlet, a real scene light outlet, a real scene light inlet, a spatial light modulator light outlet, a spatial light modulator light inlet, and an infrared imaging device light outlet in the holographic collection branch light path, wherein the spatial light modulator light outlet and the spatial light modulator light inlet coincide with each other in the holographic collection branch light path and the holographic display branch light path; the infrared imaging device is composed of a group of infrared imaging sensors and imaging lenses, and the infrared imaging sensors are located at the infrared imaging light outlet of the light guiding device.

[0021] Preferably, the light guide device comprises four beam splitters, and the light guide device has two independent, non-overlapping infrared imaging device light outlets in the holographic collection branch optical path. The infrared imaging device comprises two sets of infrared imaging sensors and imaging lenses, with the two infrared imaging sensors corresponding to the two infrared imaging light outlets of the light guide device. The axial distances between the two infrared imaging sensors and the two corresponding infrared imaging light outlets are different, and the difference between the two distances is the TIE propagation distance.

[0022] The spatial light modulator is reflective or transmissive, capable of dynamically loading the encoded hologram generated by the computational control module to modulate the illumination light and reconstruct a holographic three-dimensional image of the object. During the holographic acquisition phase, the hologram is loaded to modulate the propagation distance, and during the holographic display phase, the display image hologram is loaded to modulate the holographic display. The spatial light modulator is located at the light output port or light input port of the light guide device.

[0023] Preferably, the calculation control module at least includes:

[0024] A light source control unit, used to control the on and off of the infrared light source and visible light source according to the timing requirements of holographic acquisition and display;

[0025] An imaging control unit, configured to control the capture timing of the imaging device to ensure that the reflected light is captured at a specific propagation distance to generate an intensity map;

[0026] The data processing unit is used to receive the intensity map generated by the imaging device, solve the complex amplitude of the object based on the light intensity transmission equation, and perform hologram encoding to generate a coded hologram for holographic display.

[0027] Second, the present invention also provides a method for real-time holographic acquisition and reproduction of real scenes using the system, which is characterized by comprising:

[0028] S1: The calculation and control module controls the infrared light source module to turn on and the visible light source module to turn off, and starts the holographic acquisition process;

[0029] S2: Infrared light emitted by the infrared light source module illuminates objects in the real scene through a light guide. The reflected light carrying object information and having different propagation distances is captured successively by the infrared imaging device, generating corresponding intensity maps. The absolute value of the difference between the second propagation distance and the first propagation distance is the effective propagation distance of the light intensity transmission equation. Capturing different propagation distances can be achieved using a combination of an infrared imaging device and a spatial light modulator, or using two sets of infrared imaging devices.

[0030] S3: The calculation control module receives at least two intensity images at different propagation distances, solves the complex amplitude of the object based on the light intensity transmission equation, and performs hologram encoding to generate a coded hologram;

[0031] S4: The computing and control module controls the red and infrared light source module to turn off and the visible light source module to turn on, and the holographic display process begins;

[0032] S5: The visible light emitted by the visible light source module is irradiated onto the spatial light modulator loaded with the coded hologram through the light guide device to reconstruct a holographic three-dimensional image of the object;

[0033] S6: Repeat S1 to S5 to achieve real-time alternation of holographic acquisition and display.

[0034] Furthermore, the step S3 specifically includes:

[0035] S3.1 Substitute the two intensity images generated in step S2 into the light intensity transmission equation to obtain the phase information Φ0 at the first imaging sensor. Specifically:

[0036] S3.1.1 normalizes the two intensity maps into matrices and processes the intensity matrices to the same size. S3.1.2 aligns the two intensity maps.

[0037] S3.1.3 Substitute the two intensity images into the light intensity transfer equation solver and solve for the phase;

[0038] S3.1.4 performs phase wrapping on the solved phase and outputs the phase.

[0039] S3.2 converts the intensity information captured in step S2 into amplitude information and combines it with the obtained phase information to obtain complex amplitude wavefront information Z1 of the light wavefront in the imaging plane;

[0040] S3.3 Substitute the complex amplitude wavefront information Z1 of the imaging plane into the spatial light propagation equation ASM to obtain the complex amplitude wavefront information Z0 at the real scene;

[0041] S3.4 Encode the complex amplitude wavefront information Z0 at the real scene to obtain a hologram H for holographic display that carries the complete real scene optical information. b .

[0042] The holographic acquisition process S1-S4 and the holographic display process S5-S6 meet certain timing control requirements, including:

[0043] The duration of the holographic display process S5-S6 is longer than the duration of the holographic acquisition process S1-S4, and preferably, the duration of the holographic display process S5-S6 accounts for more than 80% of the holographic reproduction cycle time S1-S6.

[0044] The switching frame rate between the holographic acquisition process S1-S4 and the holographic display process S5-S6 is greater than 24Hz.

[0045] Compared with the prior art, the present application has the following obvious and substantial characteristics and advantages:

[0046] 1. The holographic acquisition method of the present application directly processes the two close-range intensity images captured by the light intensity transmission equation to obtain an encoded hologram that can be used for holographic display. This process combines the advantages of optical holographic methods without the need for three-dimensional modeling and fast encoding in computational holography. It avoids multiple Fourier transform calculations and the use of complex optical hardware, realizes holographic acquisition that preserves the depth information of the real scene, and achieves the effect of three-dimensional display.

[0047] 2. The device of the present application integrates the components commonly used in the holographic acquisition and holographic display processes, such as spatial light modulators and beam splitters, to obtain an integrated device that considers both holographic acquisition and holographic display functions. By precisely controlling the working timing of the infrared light source module and the visible light source module, the acquisition and display are alternately performed, avoiding light source interference, optimizing the processing flow of the calculation control module, and significantly improving the real-time performance of holographic acquisition and reproduction. Real-time three-dimensional reconstruction is achieved by calculating and generating an encoded hologram and using a spatial light modulator for fast loading.

[0048] 3. The device of the present application uses an infrared light source for holographic acquisition and a visible light source for holographic display, avoiding the influence of visible stray light generated by holographic acquisition during holographic display. By controlling the timing of the visible light source and the infrared light source through the calculation control module, considering the visual persistence effect of the human eye, a display effect of 24Hz refresh rate is achieved. BRIEF DESCRIPTION OF DRAWINGS

[0049] FIG. 1 is a structural and optical path schematic diagram of the real-time holographic acquisition and display device embodiment 1 of the present application; Figure 1 FIG. 2 is a structural and optical path schematic diagram of the real-time holographic acquisition and display device embodiment 2 of the present application;

[0050] Figure 2 FIG. 2 is a structural and optical path schematic diagram of the real-time holographic acquisition and display device embodiment 2 of the present application;

[0051] FIG. 2 is a structural and optical path schematic diagram of the real-time holographic acquisition and display device embodiment 2 of the present application;​ Figure 3 A schematic flow chart of a real-time reconstruction method for a real-time holographic acquisition and display device provided in Embodiments 1 and 2 of the present invention;

[0052] Attachment Figure 4 Schematic diagram of the timing of the real-time holographic acquisition and display method according to Example 1 of the present invention;

[0053] Attachment Figure 5 This is a timing diagram of the real-time holographic acquisition and display method according to Example 2 of the present invention.

[0054] In the figure: 100 is an infrared light source module, 101 is an infrared light source, 102 is a first collimating lens; 110 is a first light guiding device, 111 is a first beam splitter, 112 is a second beam splitter, 113 is a third beam splitter, 114 is a fourth beam splitter; 120 is a single-camera infrared imaging device, 121 is a first imaging sensor, 122 is a first imaging objective lens, 123 is a second imaging sensor, and 124 is a second imaging objective lens; 130 is a computing control module; 140 is a spatial light modulator.

[0055] 200 is a visible light source module, 201 is a visible light source, 202 is a second collimating lens; 210 is a second light guide device; 220 is a dual-camera imaging device.

[0056] It should be understood that the above drawings are merely schematic and not drawn to scale. DETAILED DESCRIPTION

[0057] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only 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 making creative efforts shall fall within the scope of protection of the present invention.

[0058] The above solution is further described below with reference to specific implementation examples. The preferred embodiments of the present invention are described in detail as follows:

[0059] Example 1

[0060] See also Figure 1 , Figure 1 This is a schematic diagram of the structure and optical path of the embodiment 1 of the real-time holographic acquisition and display device of the present invention. Figure 1 The middle dashed arrow indicates the holographic collection optical path of Example 1; Figure 1 The solid arrow in the middle represents the holographic display light path of Example 1.

[0061] like Figure 1As shown, the real-time holographic acquisition and display device of Example 1 includes an infrared light source module 100 , a first light guide device 110 , a single-camera infrared imaging device 120 , a calculation and control module 130 , a spatial light modulator 140 , and a visible light source module 200 .

[0062] The infrared light source module 100 is located at the starting position in the holographic collection optical path. The infrared light source module 100 is used to provide collimated infrared light during the holographic collection process. The infrared light source module 100 consists of an infrared light source 101 and a first collimating lens 102. The first collimating lens 102 is located on the light outlet side of the infrared light source 101. The infrared light source 101 can be a laser infrared light source, a thermal radiation infrared light source, or a gas discharge infrared light source, etc. The infrared light source 101 provides a monochromatic light wave of any wavelength in the infrared band (greater than 780nm). The infrared light source 101 is connected to the computing control module 130. During the holographic imaging process, the computing control module 130 will control the light emission timing of the infrared light source 101. The first collimating lens 102 is used to collimate the light beam emitted by the infrared light source 101.

[0063] The visible light source module 200 is located at the starting position in the holographic display optical path. The visible light source module 200 is used to provide a visible light source for reconstructing the holographic image of the object during the holographic display process. The visible light source module 200 consists of a visible light source 201 and a second collimating lens 202, and the second collimating lens 202 is located on the side of the light outlet of the visible light source 201. The visible light source 201 can be a laser, or an LED lamp, etc., wherein the laser provides a monochromatic light wave of any wavelength in the visible light band (380nm to 780nm). The second collimating lens 202 is used to collimate the light beam emitted by the visible light source 201.

[0064] The visible light source 201 is connected to the computing and control module 130. During the holographic imaging process, the computing and control module 130 controls the timing of the visible light source 201's light emission. To ensure that the holographic acquisition and display processes do not crosstalk during the holographic acquisition and display cycle, the infrared light source 101 and the visible light source 201 emit light alternately and do not overlap. Specifically, during the holographic acquisition process, the visible light source 201 is turned off and the infrared light source 101 is turned on. During the holographic display process, the visible light source 201 is turned on and the infrared light source 101 is turned off.

[0065] The first light guide device 110 consists of a first beam splitter 111, a second beam splitter 112, and a third beam splitter 113. The coated surfaces of the first beam splitter 111 and the second beam splitter 112 are positioned parallel to each other, and the coated surfaces of the second beam splitter 112 and the third beam splitter 113 are positioned symmetrically along the plane of symmetry between the two beam splitters. The first light guide device 110 has three light inputs and three light outputs in the holographic collection optical path, and two light inputs and two light outputs in the holographic display optical path. During holographic collection, the first light guide device 110 is positioned between the infrared light source module 100 and the real scene to be holographically captured, and also between the real scene to be holographically captured and the single-camera infrared imaging device 120. During holographic display, the first light guide device 110 is positioned between the visible light source module 200 and the holographically reconstructed image of the real scene. The first light guide device 110 is capable of deflecting light beams, splitting them, and directing them to appropriate locations. During the holographic acquisition phase, the infrared light source 101 can be directed to illuminate the real scene, and the reflected light from the illuminated object can be directed to enter the single-camera infrared imaging device 120. During the holographic display process, the visible light source 201 can be directed to illuminate the spatial light modulator 140, generating a holographic image of the real object.

[0066] The effect of the first light guiding device 110 on the holographic acquisition process and the holographic display process is as follows: during the holographic acquisition process, the collimated infrared light emitted by the infrared light source module 100 first enters the first beam splitter 111, and a light beam reflected by the first beam splitter 111 is irradiated on an object in the real scene and reflected. The reflected light from the object enters the first beam splitter 111 again, and a light beam transmitted through the first beam splitter 111 enters the second beam splitter 112. A light beam transmitted through the second beam splitter 112 is irradiated on the spatial light modulator 140 for modulation and reflection, and the reflected light enters the second beam splitter 112 again, and a light beam reflected by the second beam splitter 112 enters the third beam splitter 113. The light beam transmitted through the third beam splitter 113 is captured by the single-camera infrared imaging device 120 for imaging. During the holographic display process, the collimated visible light emitted by the visible light source module 200 first enters the third beam splitter 113, and a light beam reflected by the third beam splitter 113 enters the second beam splitter 112. The light beam reflected by the second beam splitter 112 is irradiated on the spatial light modulator 140 for modulation and reflection, and the reflected light enters the second beam splitter 112 again. The light beam transmitted by the second beam splitter 112 enters the first beam splitter 111, and the light beam transmitted by the first beam splitter 111 is projected into space to generate a holographic image of a real object.

[0067] The first beam splitter 111 , the second beam splitter 112 , and the third beam splitter 113 may be a combination of polygonal lenses and coatings that refract or reflect light, and are required to have the function of splitting a light beam into two or more different light beams at different angles.

[0068] The single-camera infrared imaging device 120 is located at the end of the light path during holographic acquisition and does not participate in the light path during holographic display. The single-camera infrared imaging device 120 is composed of a first imaging sensor 121 and a first imaging lens 122. The single-camera infrared imaging device 120 is used to quickly image the light waves that have passed through the first light guide device 110 after being reflected by the real scene at two different propagation distances. After the light waves reflected by the real scene are guided by the light guide device 110 and modulated by the spatial light modulator 140 twice in turn, the propagation distance of the object light waves when they reach the single-camera infrared imaging device 120 is two different propagation distances.

[0069] At the same time, the single-camera infrared imaging device 120 is connected to the computing control module 130, and the computing control module 130 controls the capturing time of the intensity map of the first imaging sensor 121 according to the time sequence of the hologram transformation of the spatial light modulator 140. Specifically, when the spatial light modulator 140 loads the first propagation distance hologram, the propagation distance of the object light waves when they reach the single-camera infrared imaging device 120 is the first propagation distance, and at this time the single-camera infrared imaging device 120 captures the first intensity map; when the spatial light modulator 140 loads the second propagation distance hologram, the propagation distance of the object light waves when they reach the single-camera infrared imaging device 120 is the second propagation distance, and at this time the single-camera infrared imaging device 120 captures the second intensity map. The first propagation distance is determined by the structure of the device and the relative spatial position with the real scene, and is a relative quantity that does not need to be determined during holographic acquisition and display. The absolute value of the difference between the second propagation distance and the first propagation distance is the effective propagation distance of the light intensity transmission equation, which is usually in the order of microns.

[0070] The first imaging sensor 121 is located behind the first imaging lens 122. The first imaging sensor 121 is used to capture two intensity maps with different propagation distances in turn, and converts the infrared light intensity signal into an electrical signal. The first imaging sensor 121 can be an infrared camera, a combination of multiple single-point infrared detectors, or any sensing device that can record infrared light intensity information. The first imaging sensor 121 is connected to the computing control module 130.

[0071] The first imaging lens 122 is used to focus the object light waves. The first imaging lens 122 makes the focal plane of the first imaging sensor 121 coincide with the equivalent plane position of the spatial light modulator 140 in the holographic acquisition light path.

[0072] The computing control module 130 is connected to the infrared light source 101, the visible light source 201, the first imaging sensor 121, and the spatial light modulator 140.

[0073] The calculation control module 130 is used to calculate the driver programs for the infrared light source 101, visible light source 201, first imaging sensor 121, and spatial light modulator 140. When calculating the driver program to load hardware parameters, it must consider the specific hardware characteristics of the infrared light source 101, visible light source 201, first imaging sensor 121, and spatial light modulator 140, such as the minimum exposure time and sensitivity of the first imaging sensor 121, the modulation frame rate of the spatial light modulator 140, and the switching timing characteristics of the infrared light source 101 and visible light source 201. The driver program controls the timing of the infrared light source 101, visible light source 201, first imaging sensor 121, and spatial light modulator 140. The timing sequence must meet the following order: the infrared light source 101 emits light, the spatial light modulator 140 loads the first propagation distance hologram, the first imaging sensor 121 captures the first intensity map, the spatial light modulator 140 loads the second propagation distance hologram, the first imaging sensor 121 captures the second intensity map, the infrared light source 101 turns off the light, the visible light source 201 emits light, the spatial light modulator 140 loads the encoded hologram, and the visible light source 201 turns off the light. The above timing sequence is repeated. The light emission time of the visible light source 201 must be longer than the light emission time of the infrared light source 101, that is, the duration of the holographic display process must be longer than the duration of the holographic acquisition process. Preferably, the duration of the holographic display process accounts for more than 80% of the cycle time of a holographic reproduction. The switching frame rate between the two light sources must be greater than 24Hz.

[0074] The calculation control module 130 is used to calculate the first propagation distance hologram and the second propagation distance hologram loaded into the spatial light modulator 140. The first propagation distance hologram and the second propagation distance hologram, when loaded into the spatial light modulator 140, can modulate the object light wave so that when the two object light waves successively reach the first imaging sensor 121, the object light wave actually propagates two different propagation distances, namely the first propagation distance and the second propagation distance. The specific calculation steps include: first, obtaining the first propagation distance hologram, i.e., a uniform phase hologram; then, based on the lens phase modulation effect formula, converting an ideal lens with a focal length equal to the propagation distance into an equivalent phase hologram or amplitude hologram. The second propagation distance hologram is the equivalent phase hologram or amplitude hologram of this lens.

[0075] The computation control module 130 is used to calculate the encoded hologram for three-dimensional display loaded by the spatial light modulator 140. Based on the two intensity images captured by the first imaging sensor 121 and the light intensity transmission equation, the complete optical information of the real scene, including amplitude and phase, is calculated and holographically encoded to form a coded hologram for computational holographic display. The specific computation steps include: substituting the two intensity images into the light intensity transmission equation to obtain the phase information at the first imaging sensor 121; combining the captured intensity information with the obtained phase information to obtain the complex amplitude information of the light wavefront at the imaging plane; substituting the complex amplitude wavefront information of the imaging plane and the distance between the first imaging sensor 121 and the real scene into the spatial light propagation equation to obtain the complex amplitude wavefront information at the real scene; encoding the light wavefront information at the complex amplitude, using a diffusion algorithm or a dual-phase encoding method, to obtain a coded hologram for holographic display that carries the complete optical information of the real scene.

[0076] The spatial light modulator 140 is located on the side of the first light guide device 110, with the second beam splitter 112 in front and behind in the optical path. During the holographic acquisition process, the spatial light modulator 140 is used to modulate the object light wave, causing the propagation distance of the light wave to change, and cooperates with the single-camera infrared imaging device 120 to capture the light waves reflected by the real object at two different propagation distances. During the holographic display stage, the spatial light modulator 140 loads the encoded hologram generated by the holographic acquisition process for three-dimensional display, modulates the light wavefront, and ultimately displays the holographic image. The spatial light modulator 140 can be an amplitude-type spatial light modulator or a phase-type spatial light modulator. In this embodiment, the spatial light modulator 140 is a reflective spatial light modulator. When the device is modified based on non-inventive structure, the spatial light modulator 140 can also be a transmissive spatial light modulator.

[0077] The spatial light modulator 140 is connected to the computation and control module 130, which is used to control the holograms loaded onto the spatial light modulator 140. During the holographic acquisition process, the spatial light modulator 140 first loads the first propagation distance hologram. At this time, the object light wave reaches the single-camera infrared imaging device 120 and is captured as a first intensity map. After the first intensity map is recorded, the spatial light modulator 140 loads the second propagation distance hologram. At this time, the object light wave reaches the single-camera infrared imaging device 120 and is captured as a second intensity map. The first propagation distance hologram is the hologram loaded onto the spatial light modulator 140 corresponding to the object light wave at the first propagation distance, and the second propagation distance hologram is the hologram loaded onto the spatial light modulator 140 corresponding to the object light wave at the second propagation distance. The computation and control module 130 calculates the first and second propagation distance holograms based on the phase modulation effect of the lens and the laws of spatial light diffraction. During the holographic display stage, the spatial light modulator 140 is controlled by the computational control module 130 to load the encoded hologram generated through the holographic acquisition process for three-dimensional display.

[0078] The hologram loading sequence for the spatial light modulator 140 is as follows: during holographic acquisition, the first propagation distance hologram is loaded after the infrared light source 101 is turned on. After the single-camera infrared imaging device 120 captures the first intensity image, the second propagation distance hologram is loaded. During holographic display, the encoded hologram for 3D display is loaded after the visible light source is turned on. This process repeats continuously.

[0079] Example 2

[0080] See also Figure 2 , Figure 2 Schematic diagram of the structure and optical path of embodiment 2 of the real-time holographic acquisition and display device of the present invention. Figure 2 The middle dashed arrow indicates the holographic collection optical path of Example 2; Figure 2 The solid arrow in the middle represents the holographic display light path of Example 2.

[0081] like Figure 2 As shown, the real-time holographic acquisition and display device of Example 2 includes an infrared light source module 100 , a second light guide device 210 , a dual-camera infrared imaging device 220 , a calculation and control module 130 , a spatial light modulator 140 , and a visible light source module 200 .

[0082] The second light guide device 210 is composed of a first beam splitter 111, a second beam splitter 112, a third beam splitter 113, and a fourth beam splitter 114. The second light guide device 210 has two light inputs and three light outputs in the holographic collection optical path, and two light inputs and two light outputs in the holographic display optical path. During the holographic collection process, the second light guide device 210 is located between the infrared light source module 100 and the real scene to be holographically collected, and also between the real scene to be holographically collected and the dual-camera infrared imaging device 220. During the holographic display process, the second light guide device 210 is located between the visible light source module 200 and the reconstructed image of the real scene displayed holographically.

[0083] The second light guide 210 deflects and splits the light beams, directing them to appropriate locations. During the holographic acquisition phase, it guides the illumination light from the infrared light source 101 to illuminate the real scene and also guides the reflected light from the illuminated object into the dual-camera infrared imaging device 220. During the holographic display process, it guides the illumination light from the visible light source 201 to illuminate the spatial light modulator 140, generating a holographic image of the real object.

[0084] The effect of the second light guiding device 210 on the holographic acquisition process and the holographic display process is as follows: during the holographic acquisition process, the collimated infrared light emitted by the infrared light source module 100 first enters the third beam splitter 113, and a light beam transmitted through the third beam splitter 113 enters the second beam splitter 112. A light beam reflected through the second beam splitter 112 irradiates an object in the real scene and reflects. The reflected light from the object enters the second beam splitter 112 again, and a light beam transmitted through the second beam splitter 112 enters the fourth beam splitter 114. The light beam transmitted through the fourth beam splitter 114 is captured by the dual-camera infrared imaging device 220 and the light beam reflected through the fourth beam splitter 114 is also captured by the dual-camera infrared imaging device 220. During the holographic display process, the collimated visible light emitted by the visible light source module 200 first enters the third beam splitter 113, and a light beam reflected by the third beam splitter 113 enters the second beam splitter 112. A light beam transmitted by the second beam splitter 112 enters the first beam splitter 111, and a light beam reflected by the first beam splitter 111 is irradiated onto the spatial light modulator 140 for modulation and reflection. The reflected light enters the first beam splitter 111 again, and the light beam transmitted by the first beam splitter 111 is projected into space to generate a holographic image of a real object.

[0085] The fourth beam splitter 114 may be a combination of a polygonal lens and a coating that refracts or reflects light, and is required to have the function of splitting a light beam into two or more different light beams at two angles.

[0086] The dual-camera infrared imaging device 220 is located at the end of the optical path during holographic acquisition and does not participate in the optical path during holographic display. It is used to rapidly image light waves reflected from the real scene and passing through the second light guide 210 at two different propagation distances. It consists of a first imaging sensor 121 and a first imaging lens 122, and a second imaging sensor 123 and a second imaging lens 124.

[0087] The distance between the first imaging sensor 121 and the fourth beam splitter 114 is different from the distance between the second imaging sensor 123 and the fourth beam splitter 114. The light wave reflected by the real scene is split into two beams after passing through the light guide device 110, and enters the first imaging sensor 121 and the second imaging sensor 123 respectively. The object light wave travels two different propagation distances when reaching the first imaging sensor 121 and the second imaging sensor 123 of the dual-camera infrared imaging device 220, respectively.

[0088] At the same time, the dual-camera infrared imaging device 220 is connected to the calculation control module 130, which controls the intensity map capture time of the first imaging sensor 121 and the second imaging sensor 123 according to the timing of the visible light source 201 and the infrared light source 101.

[0089] Specifically, when the infrared light source 101 is turned on, the object light wave propagates along a first propagation distance when it reaches the first imaging sensor 121 in the dual-camera infrared imaging device 220. At this point, the first imaging sensor 121 captures the first intensity map. Simultaneously, the object light wave propagates along a second propagation distance when it reaches the second imaging sensor 123 in the dual-camera infrared imaging device 220. At this point, the second imaging sensor 123 captures the second intensity map. The first propagation distance is determined by the distance between the first imaging sensor 121 and the real scene, while the second propagation distance is determined by the distance between the second imaging sensor 123 and the real scene. The second propagation distance and the first propagation distance do not need to be determined during the holographic acquisition and display process. The absolute value of the difference between the second propagation distance and the first propagation distance is the propagation distance for which the light intensity transmission equation is valid, typically on the order of microns. Only the difference between the second propagation distance and the first propagation distance needs to be determined.

[0090] The second imaging sensor 123 is located behind the second imaging lens 124. It is used to sequentially capture two intensity images with different propagation distances, converting the infrared light intensity signal into an electrical signal. The second imaging sensor 123 can be an infrared camera, a combination of multiple single-point infrared detectors, or any other sensing device capable of recording infrared light intensity information. The second imaging sensor 123 is connected to the computing and control module 130.

[0091] The second imaging lens 124 is used to focus the object light wave. The focal length of the second imaging lens 124 is the same as that of the first imaging lens 122.

[0092] The calculation and control module 130 is connected to the infrared light source 101 , the visible light source 201 , the first imaging sensor 121 , the second imaging sensor 123 , and the spatial light modulator 140 .

[0093] The calculation and control module 130 is used to calculate the driver programs for the infrared light source 101, visible light source 201, first imaging sensor 121, second imaging sensor 123, and spatial light modulator 140. This driver program is calculated based on the specific hardware characteristics of the infrared light source 101, visible light source 201, first imaging sensor 121, second imaging sensor 123, and spatial light modulator 140, such as the minimum exposure time and sensitivity of the first imaging sensor 121, the modulation frame rate of the spatial light modulator 140, and the switching timing characteristics of the infrared light source 101 and visible light source 201. The driver program controls the timing of the infrared light source 101, visible light source 201, first imaging sensor 121, second imaging sensor 123, and spatial light modulator 140. The timing sequence must meet the following order: infrared light source 101 emits light, first imaging sensor 121 captures the first intensity image and second imaging sensor 123 captures the second intensity image, infrared light source 101 turns off, visible light source 201 emits light, spatial light modulator 140 loads the encoded hologram, and visible light source 201 turns off. The above timing sequence repeats itself.

[0094] The computation control module 130 is used to calculate the coded hologram for 3D display loaded by the spatial light modulator 140. Based on the two intensity images captured by the first imaging sensor 121 and the second imaging sensor 123 and the light intensity transmission equation, it calculates the complete optical information of the real scene, including amplitude and phase, and performs holographic encoding to encode it into a coded hologram for computer-generated holographic display.

[0095] The spatial light modulator 140 is located at the side of the second light guide device 210, and the first beam splitter 111 is located in front and behind the spatial light modulator 140 in the light path. In the holographic display stage, the spatial light modulator 140 loads the encoded hologram for three-dimensional display generated through the holographic acquisition process to modulate the light wave front, and finally displays the holographic image. The spatial light modulator 140 is connected with the computing control module 130, and the computing control module 130 is used for controlling the loading of the hologram of the spatial light modulator 140. In the holographic display stage, the spatial light modulator 140 is controlled by the computing control module 130 to load the encoded hologram for three-dimensional display generated through the holographic acquisition process. The loading time sequence of the hologram of the spatial light modulator 140 is as follows: in the holographic acquisition process, the first uniform phase hologram is loaded after the infrared light source 101 is turned on; in the holographic display process, the encoded hologram for three-dimensional display is loaded after the visible light source is turned on. The above process is continuously cycled.

[0096] The real-time holographic acquisition and display method based on the light intensity transmission equation provided in Embodiments 1 and 2 of the present application is shown in Figure 3 , and the method comprises the following steps.

[0097] First step: the computing control module controls the infrared light source to emit light and the visible light source to stop emitting light.

[0098] Second step: the computing control module calculates a first hologram H1 and a second hologram H2. The first hologram is calculated as a fixed uniform phase hologram. According to the phase modulation effect of the lens and the diffraction propagation law, the second hologram H2 is calculated as an equivalent phase hologram or an amplitude hologram of an ideal lens with a focal length equal to the propagation distance.

[0099] Third step: the computing control module controls the spatial light modulator to load the first hologram H1 and the second hologram H2 respectively, and controls the imaging device to capture a first intensity image A1 and a second intensity image A2 respectively.

[0100] Fourth step: the computing control module calculates an encoded hologram H b for holographic display. The two intensity images are subjected to regularization processing and alignment processing, and then substituted into a light intensity transmission equation solver to solve the phase, and the solved phase is subjected to phase wrapping to output a phase Φ0. The captured intensity information is converted into amplitude information and combined with the solved phase Φ0 to obtain complex amplitude wave front information Z1 of the light wave front of the imaging plane. The complex amplitude wave front information of the imaging plane is substituted into a spatial light propagation equation to obtain complex amplitude wave front information Z0 of the real scene. The complex amplitude wave front information is encoded to obtain the hologram H b for holographic display carrying complete optical information of the real scene.

[0101] Fifth step: the computing control module controls the infrared light source to stop emitting light and the visible light source to emit light.

[0102] Step 6: The illumination light from the visible light source is irradiated onto the spatial light modulator, and the coded hologram H for holographic display loaded by the spatial light modulator is b After modulation, it is projected to a specific location in space to form a holographic image Z0 of the real scene ’ ;

[0103] Step 7: Repeat steps 1 to 6 to achieve real-time holographic acquisition and display.

[0104] 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. Under the concept of the present invention, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the present invention as described above. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above 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 scope of the technical solutions of the embodiments of the present invention.

Claims

1. A real-time holographic acquisition and reproduction system for real scenes, characterized by: include: an infrared light source module configured to provide collimated infrared light during a holographic acquisition process; a visible light source module configured to provide collimated visible light during holographic display; a light guiding device configured as at least three beam splitters for deflecting, splitting and guiding the light beam; Specifically, the method includes transmitting the infrared light emitted by the infrared light source module to an object in a real scene during a holographic acquisition process, and guiding the reflected light of the object to be transmitted to an imaging device through a spatial light modulator, and transmitting the visible light emitted by the visible light source module to a spatial light modulator during a holographic display process to generate a holographic image of the object; Infrared imaging device, used to capture reflected light with different propagation distances carrying object information during the holographic acquisition process, and generate corresponding intensity maps; The computing control module is respectively connected to the infrared light source module, the visible light source module, the light guide device, and the infrared imaging device and controls their working timing. Specifically, the computing control module controls the light emission timing of the infrared light source module and the visible light source module to ensure that the two emit light alternately without overlapping. During the holographic acquisition process, that is, when the infrared light source module is turned on and the visible light source module is turned off, the computing control module controls the infrared imaging device to capture reflected light at at least two different propagation distances and generates at least two corresponding intensity maps, wherein the absolute value of the difference between the second propagation distance and the first propagation distance is the effective propagation distance of the light intensity transmission equation, and by processing and calculating the two intensity maps, a coded hologram carrying object information is obtained; during the holographic display process, that is, when the infrared light source module is turned off and the visible light source module is turned on, the computing control module controls the spatial light modulator to load the coded hologram and generate a holographically reconstructed three-dimensional image of the object.

2. The real-time holographic acquisition and reproduction system for real scenes according to claim 1, characterized in that: The effective propagation distance of the light intensity transmission equation is 1 to 10 microns.

3. The real-time holographic acquisition and reproduction system for real scenes according to claim 1 or 2, characterized in that: The infrared light source module includes an infrared light source and an infrared collimating lens, the visible light source module includes a visible coherent light source and a visible collimating lens, and the infrared imaging device includes an infrared imaging sensor and an imaging lens. The spatial light modulator is connected to the computing and control module and is used to modulate the object light wave during the holographic acquisition process to change the propagation distance of the light wave. And loading the encoded hologram during the holographic display process to generate a holographic image of the object; wherein, during the holographic acquisition process, the infrared imaging device, with the assistance of a spatial light modulator, successively captures reflected light carrying object information and with different propagation distances, and generates a corresponding intensity map.

4. The real-time holographic acquisition and reproduction system for real scenes according to claim 1 or 2, characterized in that: The infrared light source module includes an infrared light source and an infrared collimating lens, the visible light source module includes a visible coherent light source and a visible collimating lens, and the infrared imaging device includes at least two groups of infrared imaging sensors and imaging lenses, ensuring that reflected light carrying object information and with different propagation distances is captured during the holographic acquisition process and generating a corresponding intensity map.

5. The real-time holographic acquisition and reproduction system for real scenes according to any one of claims 1 to 4, characterized in that: The infrared imaging device is used to capture infrared light and generate corresponding electrical signals.

6. The real-time holographic acquisition and reproduction system for real scenes according to any one of claims 1 to 4, characterized in that: The spatial light modulator is reflective or transmissive and can dynamically load the coded hologram generated by the computing control module to modulate the illumination light and reconstruct a holographic three-dimensional image of the object.

7. The real-time holographic acquisition and reproduction system for real scenes according to any one of claims 1 to 4, characterized in that: The calculation control module at least includes: A light source control unit, used to control the on and off of the infrared light source and visible light source according to the timing requirements of holographic acquisition and display; An imaging control unit, configured to control the capture timing of the imaging device to ensure that the reflected light is captured at a specific propagation distance to generate an intensity map; The data processing unit is used to receive the intensity map generated by the imaging device, solve the complex amplitude of the object based on the light intensity transmission equation, and perform hologram encoding to generate a coded hologram for holographic display.

8. A method for real-time holographic acquisition and reproduction of a real scene using the system according to any one of claims 1 to 7, characterized in that: include: S1: The calculation and control module controls the infrared light source module to turn on and the visible light source module to turn off, and starts the holographic acquisition process; S2: Infrared light emitted by the infrared light source module illuminates objects in the real scene through a light guide. The reflected light carrying object information and having different propagation distances is captured successively by the infrared imaging device, generating corresponding intensity maps. The absolute value of the difference between the second propagation distance and the first propagation distance is the effective propagation distance of the light intensity transmission equation. Capturing different propagation distances can be achieved using a combination of an infrared imaging device and a spatial light modulator, or using two sets of infrared imaging devices. S3: The calculation control module receives at least two intensity images at different propagation distances, solves the complex amplitude of the object based on the light intensity transmission equation, and performs hologram encoding to generate a coded hologram; S4: The computing and control module controls the red and infrared light source module to turn off and the visible light source module to turn on, and the holographic display process begins; S5: The visible light emitted by the visible light source module is irradiated onto the spatial light modulator loaded with the coded hologram through the light guide device to reconstruct a holographic three-dimensional image of the object; S6: Repeat S1 to S5 to achieve real-time alternation of holographic acquisition and display.

9. The method for real-time holographic acquisition and reproduction of a real scene according to claim 8, characterized in that: The step S3 specifically includes: S3.1 Substitute the two intensity images generated in step S2 into the light intensity transfer equation to obtain the phase information Φ0 at the first imaging sensor; S3.2 converts the intensity information captured in step S2 into amplitude information and combines it with the obtained phase information to obtain complex amplitude wavefront information Z1 of the light wavefront in the imaging plane; S3.3 Substitute the complex amplitude wavefront information Z1 of the imaging plane into the spatial light propagation equation ASM to obtain the complex amplitude wavefront information Z0 at the real scene; S3.4 Encode the complex amplitude wavefront information Z0 at the real scene to obtain a hologram H for holographic display that carries the complete real scene optical information. b .

10. The method for real-time holographic acquisition and reproduction of a real scene according to claim 8, characterized in that: S3.1, according to the light intensity transmission equation, substitutes the two intensity images to obtain the phase information Φ0 at the first imaging sensor, specifically comprising the following steps: S3.1.1 Normalize the two intensity maps into matrices and process the intensity matrices to the same size. S3.1.2 align the two intensity maps; S3.1.3 Substitute the two intensity images into the light intensity transfer equation solver and solve for the phase; S3.1.4 performs phase wrapping on the solved phase and outputs the phase.

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