Digital filtering large-size holographic wavefront overlapping printing system and printing method

Abstract

The invention belongs to the field of holographic printing, and particularly discloses a digital filtering large-size holographic wavefront overlapping printing system and method, and the method comprises the steps: determining a plurality of element holograms to be printed at a plurality of printing positions of a holographic recording medium, printing a large-size hologram formed by splicing the plurality of element holograms on a holographic recording medium; the adjacent printing positions are overlapped, and overlapping areas exist between the corresponding adjacent element holograms; when each overlapping region of the current element hologram is printed, regulating and controlling the exposure dose of each overlapping region by adopting a digital filtering mode; the digital filtering mode is that the exposure dose of the overlapping area is controlled to change progressively from the first-class boundary to the second-class boundary; the first type of boundaries are boundaries only belonging to the boundaries of the current element hologram in the boundaries of the overlapping region, and the second type of boundaries are boundaries only belonging to the boundaries of the adjacent element holograms in the boundaries of the overlapping region. By means of the holographic printing device, large-size small-gap or even seamless holographic printing is achieved.

Description

Technical Field

[0001] The present application belongs to the field of holographic printing, and more specifically, to a digital filtering large-size holographic wavefront overlap printing system and printing method. Background Art

[0002] Holographic technology is a technology that uses the principles of interference and diffraction to record and reproduce the three-dimensional image of an object. It is widely used in data storage, imaging, security, art and other fields. With the development of computer technology and the emergence of spatial light modulators, complex mathematical calculations and image processing have become possible. Holograms can be generated by calculation, and by loading the generated holograms onto the spatial light modulator, holographic printing is achieved by diffraction and interference of laser beams. Compared with traditional optical holography, holographic printing technology can generate scenes that do not exist in reality through computers, and print and store their light field information in holographic recording media, which has the advantages of high repeatability and low cost.

[0003] In recent years, with the development of photopolymer materials, holographic storage and imaging technology has made significant progress. Photopolymer materials have become an ideal choice for holographic recording media due to their high resolution, good optical transparency and strong resistance to environmental interference. However, holographic photopolymer materials are based on the principle of photopolymerization-induced phase separation, that is, polymers diffuse through microscopic phase separation to form holographic microstructures that record three-dimensional holographic images. This process will cause the effective components at the edge to diffuse and be consumed, and then the edge area cannot continue to record the effective information of the hologram, and gaps will form in the area that cannot be recorded during the splicing printing process.

[0004] At present, holograms larger than 10 cm in size are basically printed by splicing. For example, the non-patent document "Partially Overlapping Printing with Digital Filter to Improve Quality of Volume Hologram Printer – Numerical Simulation" [Applied Sciences-Basel 2020, 10(11):3963] discloses a numerical simulation method for improving the quality of volume hologram printers by partially overlapping printing with digital filters. During the molding process of holographic recording materials, the edge phenomenon of polymer molecular chains under the action of the light field makes it impossible to eliminate the splicing gap in splicing printing, which seriously affects the quality of large-size holographic wavefront printing and restricts the development of holographic wavefront printing technology. Summary of the invention

[0005] In view of the defects of the prior art, the purpose of this application is to provide a digital filtering large-size holographic wavefront overlapping printing system and printing method, aiming to solve the problem of splicing gaps in the existing large-size splicing printing of holographic wavefronts.

[0006] To achieve the above objectives, in a first aspect, the present application provides a digital filtering large-size holographic wavefront overlapping printing method, comprising: Determine a plurality of elementary holograms to be printed at a plurality of printing positions of a holographic recording medium, respectively, so as to print a large-size hologram formed by splicing the plurality of elementary holograms on the holographic recording medium; there is partial overlap between adjacent printing positions, and there is an overlapping area between corresponding adjacent elementary holograms; each elementary hologram includes at least one overlapping area; When printing the overlapping areas of the current elementary hologram, the exposure dose of each overlapping area is regulated by a digital filtering method; the digital filtering method is: controlling the exposure dose of the overlapping area to change incrementally from the first type of boundary to the second type of boundary; the first type of boundary is the boundary that only belongs to the boundary of the current elementary hologram in the boundaries of the overlapping area, and the second type of boundary is the boundary that only belongs to the boundary of its adjacent elementary hologram in the boundaries of the overlapping area; so as to reduce the diffusion consumption of the holographic recording medium at the corresponding splicing position of its adjacent elementary hologram when printing the current elementary hologram, weaken the splicing gap when the printed adjacent elementary holograms are spliced ​​through the overlapping area, and ensure that the exposure dose of each overlapping area is uniform.

[0007] It should be noted that, due to the limitation of the existing technology level, large-size holograms that need to be printed cannot be printed all at once, so they can be cut into multiple elementary holograms for splicing and printing.

[0008] It can be understood that in view of the situation that there are splicing gaps in the existing splicing printing, the present application adopts the method of overlapping splicing printing, that is, there are overlapping areas between adjacent printing positions, and part of a printing position is repeatedly printed with the same holographic information. In order to reduce the diffusion consumption of the polymer at the boundary of a certain elementary hologram to the holographic recording medium of its adjacent printing position (that is, the splicing position of adjacent elementary holograms) through microscopic phase separation diffusion, the present application adjusts the exposure dose of the overlapping area by digital filtering, so that the exposure dose at the boundary of the elementary hologram currently printed is the lowest (that is, the exposure dose of the first type of boundary in the overlapping area is the lowest), so as to greatly reduce the corresponding diffusion consumption; at this time, the exposure dose of the second type of boundary is the highest, and it can be seen that the exposure dose of the overlapping area is uneven at this time. Further, in order to ensure the overall uniformity of the exposure dose of the overlapping area, the digital filtering methods of adjacent elementary holograms cooperate with each other, and the exposure dose regulation method changes in an opposite law (when printing adjacent elementary holograms, the exposure dose at the second type of boundary is the lowest, and the exposure dose at the first boundary is the highest), so as to achieve the uniformity of the overall exposure dose of the overlapping area, and further ensure the quality of the hologram on the basis of weakening the splicing gap.

[0009] In a possible implementation, a large-size hologram formed by splicing a plurality of elementary holograms is printed on a holographic recording medium, including: the plurality of elementary holograms are repeatedly printed multiple times until a predetermined exposure dose is reached to obtain the printed large-size hologram; so as to weaken the exposure dose of each overlapping area of ​​a single print, and further weaken the splicing gap between adjacent elementary holograms.

[0010] Usually, the predetermined exposure dose is determined according to the spot intensity of the large-size hologram to be printed, so that the spot intensity of the large-size hologram finally printed meets the preset requirement.

[0011] It is understandable that if multiple elementary holograms are printed only once according to a predetermined exposure dose, even if the exposure dose of the overlapping area is adjusted according to the above filtering method, the basic amplitude of the dose during a single printing is still relatively high, so it may also introduce a certain amount of diffusion consumption of the holographic recording medium, resulting in a less than ideal weakening effect of the splicing gap. Therefore, the present application can divide the predetermined exposure dose into multiple parts, and repeatedly print multiple elementary holograms to accumulate the exposure dose to the predetermined exposure dose; the advantage of doing so is that the exposure dose is greatly reduced each time the elementary hologram is printed. At this time, combined with the above filtering method, the diffusion consumption of the holographic recording medium can be further greatly reduced, so the weakening effect of the above splicing gap can be further significantly improved.

[0012] In a possible implementation, if the elementary hologram includes a plurality of overlapping regions, the exposure dose is regulated in each overlapping region by using the digital filtering method; And / or if the elementary hologram includes multiple overlapping areas, and there are overlapping areas between at least two overlapping areas among the multiple overlapping areas, then the exposure dose of each overlapping area is regulated by the digital filtering method, and the exposure dose of the overlapping area between the at least two overlapping areas is regulated by the superposition of the digital filtering methods of the at least two overlapping areas.

[0013] It can be understood that if there is further overlap between the overlapping areas, it can be called a secondary overlapping area; obviously, the number of printing times in the secondary overlapping area will increase from two printings to four printings, so two digital filtering methods are used in a single printing to further control the exposure dose (further reduce the exposure dose). At this time, the combined four cumulative printings can still keep the total exposure dose of the entire secondary overlapping area uniform.

[0014] In a possible implementation, the digital filtering method is specifically as follows: controlling the exposure dose of the overlapping area to vary linearly or nonlinearly from the first type of boundary to the second type of boundary; and each time the large-size hologram is printed, the total exposure dose at each position of each overlapping area is within a preset dose range.

[0015] In a possible implementation, each elementary hologram further includes: a non-overlapping area, where the non-overlapping area is an area belonging only to a single elementary hologram; and / or The preset dose range is equivalent to the exposure dose of the non-overlapping area when printing the large-size hologram once.

[0016] In a possible implementation, the plurality of elementary holograms are distributed in rows and columns; the elementary holograms adjacent to each other in the upper and lower rows have an overlapping region in the row direction, and the elementary holograms adjacent to each other in the left and right columns have an overlapping region in the column direction; The overlapping area of ​​each elementary hologram includes at least one of a left column overlapping area, a right column overlapping area, an upper row overlapping area and a lower row overlapping area; there are also overlapping areas between any column overlapping area and any row overlapping area; The first type of boundary in the column overlap region within the current elementary hologram is the column boundary in the overlap region belonging to the current elementary hologram, and the second type of boundary is the column boundary in the overlap region belonging to the column adjacent elementary hologram; The first type of boundary in the row overlapping area within the current elementary hologram is the row boundary in the overlapping area belonging to the current elementary hologram, and the second type of boundary is the row boundary in the overlapping area belonging to the row adjacent elementary hologram.

[0017] In a possible implementation, the sizes of the elementary holograms are the same; and / or the area ratio of the overlapping regions between adjacent elementary holograms is less than 50%; And / or the digital filtering method is loaded on each elementary hologram, so as to adjust the light spot intensity of each overlapping area of ​​the elementary hologram to be printed, so as to realize the regulation of the exposure dose.

[0018] In a second aspect, the present application provides a digital filtering large-size holographic wavefront overlap printing system, including: an optical module and a control module; The optical module is used to provide the optical signal required for printing a large-size hologram on a holographic recording medium; The control module is used to cut the large-size hologram into a plurality of elementary holograms; there are overlapping areas between adjacent elementary holograms; each elementary hologram includes at least one overlapping area; The control module is further used to control the optical module to print the plurality of elementary holograms at a plurality of printing positions respectively; there are parts of adjacent printing positions, and the positions where the parts overlap correspond to the overlapping areas; The control module is also used to control the exposure dose of each overlapping area by digital filtering when printing each overlapping area of ​​the current elementary hologram; the digital filtering method is: controlling the exposure dose of the overlapping area to change incrementally from the first type of boundary to the second type of boundary; the first type of boundary is the boundary that only belongs to the boundary of the current elementary hologram in the boundaries of the overlapping area, and the second type of boundary is the boundary that only belongs to the boundary of its adjacent elementary hologram in the boundaries of the overlapping area; so as to reduce the diffusion consumption of the holographic recording medium at the corresponding splicing position of its adjacent elementary hologram when printing the current elementary hologram, weaken the splicing gap when the printed adjacent elementary holograms are spliced ​​through the overlapping area, and ensure that the exposure dose of each overlapping area is uniform.

[0019] In a possible implementation, the control module is also used to control the repeated printing of the multiple elementary holograms until a predetermined exposure dose is reached to obtain the printed large-size hologram; so as to weaken the exposure dose of each overlapping area of ​​a single print and further weaken the splicing gap between adjacent elementary holograms.

[0020] In a third aspect, the present application provides an electronic device comprising: at least one memory for storing programs; and at least one processor for executing the programs stored in the memory. When the program stored in the memory is executed, the processor is used to execute the method described in the first aspect or any possible implementation of the first aspect.

[0021] In a fourth aspect, the present application provides a computer-readable storage medium, which stores a computer program. When the computer program runs on a processor, the processor executes the method described in the first aspect or any possible implementation of the first aspect.

[0022] In a fifth aspect, the present application provides a computer program product. When the computer program product runs on a processor, the processor executes the method described in the first aspect or any possible implementation of the first aspect.

[0023] It can be understood that the beneficial effects of the second to fifth aspects mentioned above can be found in the relevant description of the first aspect mentioned above, and will not be repeated here.

[0024] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the prior art: The present application provides a digital filtering large-scale holographic wavefront overlapping printing system and printing method. In view of the situation that there are splicing gaps in the existing splicing printing, an overlapping splicing printing method is adopted, that is, there are overlapping areas between adjacent printing positions, and the same holographic information is repeatedly printed in a part of a printing position. In order to reduce the diffusion consumption of the polymer at the boundary of a certain elementary hologram to the holographic recording medium of its adjacent printing position (that is, the splicing position of adjacent elementary holograms) through microscopic phase separation diffusion, the present application adjusts the exposure dose of the overlapping area by digital filtering, so that the exposure dose at the boundary of the elementary hologram currently printed is the lowest (that is, the exposure dose of the first type of boundary in the overlapping area is the lowest), so as to greatly reduce the corresponding diffusion consumption; at this time, the exposure dose of the second type of boundary is the highest, and it can be seen that the exposure dose of the overlapping area is uneven at this time. Furthermore, in order to ensure the overall uniformity of the exposure dose in the overlapping area, the digital filtering methods of adjacent elementary holograms cooperate with each other, and the exposure dose regulation method changes in an opposite pattern (when printing adjacent elementary holograms, the exposure dose at the second type of boundary is the lowest, and the exposure dose at the first boundary is the highest), thereby achieving the uniformity of the overall exposure dose in the overlapping area, and further ensuring the quality of the hologram on the basis of weakening the splicing gap.

[0025] The present application provides a digital filtering large-size holographic wavefront overlapping printing system and printing method, which divides a predetermined exposure dose (the predetermined exposure dose is determined according to the spot intensity of the large-size hologram to be printed) into multiple parts, repeatedly prints multiple elementary holograms to accumulate the exposure dose to the predetermined exposure dose, and finally obtains a printed large-size hologram; the above-mentioned repeated printing method greatly reduces the exposure dose when printing the elementary hologram each time, and at this time, combined with the above-mentioned filtering method, it can further greatly reduce the diffusion consumption of the holographic recording medium, so that the weakening effect of the above-mentioned splicing gap can be further significantly improved.

[0026] The present application provides a digital filtering large-size holographic wavefront overlapping printing system and printing method. Since the present application significantly improves the quality of holographic printing, the application scope of holograms is also expected to be broadened, especially in the fields of high-end anti-counterfeiting, holographic optical elements and three-dimensional display. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic diagram of the architecture of a holographic printing device provided in an embodiment of the present application; Figure 2 It is a schematic diagram of the rotation control of the xy electric-controlled translation stage and the reflector provided in the embodiment of the present application; Figure 3 It is a flow chart of the digital filtering large-size holographic wavefront overlapping printing method provided in the embodiment of the present application; Figure 4 It is a schematic diagram of the row and column distribution of the partially overlapped printed elementary hologram provided in the embodiment of the present application; Figure 5 is a schematic diagram of the overlapping area provided in the embodiment of the present application; Figure 6 The embodiments of the present application provide different digital filtering methods and their effects on the hologram object light spot; Figure 7 is a three-dimensional schematic diagram of a digital filtering method provided in an embodiment of the present application; Figure 8 It is a plan view of a digital filtering method provided in an embodiment of the present application; Fig. 9 This is a diagram showing the effect of the object light spot using a hologram provided in an embodiment of the present application; Fig.10 It is a large-size hologram of three-dimensional scene information provided by the embodiment of the present application; Fig.11 It is a schematic diagram of the cyclic overlapping printing result of a large-size holographic wavefront plane hologram provided in an embodiment of the present application; Fig.12 It is a schematic diagram of the large-scale holographic wavefront overlapping printing result provided by the trial embodiment of the present application; Fig.13 This is a diagram of the printing imaging effect of an optical element provided in an embodiment of the present application; Fig.14 It is an architecture diagram of a digital filtering large-size holographic wavefront overlap printing system provided in an embodiment of the present application; Fig.15 is an architecture diagram of an electronic device provided in an embodiment of the present application; Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein: 101 is a laser, 102 is an electronic shutter, 103 is a half-wave plate, 104 is a first beam splitter prism, 123 is a second beam splitter prism, 111 is a first filter, 121 is a second filter, 122 is a first spatial filter, 113 is a second spatial filter, L1 is a first Fourier transform lens, L2 is a second Fourier transform lens, L3 is a third Fourier transform lens, L4 is a fourth Fourier transform lens, 112 is a reflector, LCoS is a spatial light modulator, 124 is a light trap, 125 is a bandpass filter, 114 is an electrically controlled aperture, 115 is a translation guide, 201 is an xy electrically controlled translation stage, 300 is a holographic recording device, 400 is a control module, and 500 is a CCD camera. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0029] The term "and / or" in this article is a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. The symbol " / " in this article indicates that the associated objects are in an or relationship, for example, A / B means A or B.

[0030] The terms "first" and "second" in the specification and claims herein are used to distinguish different objects rather than to describe a specific order of objects. For example, a first-class boundary and a second-class boundary are used to distinguish different boundaries rather than to describe a specific order of boundaries.

[0031] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0032] In the description of the embodiments of the present application, unless otherwise specified, the meaning of "plurality" refers to two or more than two. For example, a plurality of elementary holograms refers to two or more elementary holograms, and the like.

[0033] First, the technical terms involved in the embodiments of the present application are introduced.

[0034] (1) Elementary hologram The elementary hologram is the basic unit of the hologram, which records the light wave information of a local object or a specific viewing angle and is used to splice into a complete holographic image. It can be understood as a single-printed hologram. (2) Diffusion consumption In the embodiment of the present application, diffusion consumption refers to when a single elementary hologram is printed and printed to the boundary of its holographic recording medium, since the principle of the holographic recording medium is that polymers diffuse through microscopic phase separation to form a recorded three-dimensional holographic image, in the area where holographic printing is being performed, the internal material will react and be consumed to form a holographic grating, and the material outside its boundary will diffuse into the printing area to react and be consumed, forming a circle of unreactive gap area. This phenomenon can be understood as diffusion consumption.

[0035] It is understandable that diffusion consumption is unavoidable for splicing holographic printing. Usually, if a certain degree of diffusion consumption is caused, when the corresponding position (i.e., the splicing gap) is subsequently printed, the holographic recording medium is partially or completely consumed by pre-diffusion. At this time, the three-dimensional holographic image cannot be printed at the splicing gap or the spot intensity of the printed three-dimensional holographic image is very weak. Therefore, the embodiment of the present application provides an improved overlapping holographic printing method to weaken or remove the splicing gap.

[0036] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0037] Example 1 Figure 1 It is a schematic diagram of the architecture of the holographic printing device provided in the embodiment of the present application; it can be seen that the holographic printing device provided in this embodiment 1 includes: an optical system, a displacement device, a holographic recording device 300, a control module 400 and a CCD camera 500 as an image sensor.

[0038] The optical system includes a laser 101, an electronic shutter 102, a half-wave plate 103, a first beam splitter prism 104, a second beam splitter prism 123, a first filter 111, a second filter 121, a first spatial filter 122, a second spatial filter 113, a first Fourier transform lens L1, a 4f system (composed of a second Fourier transform lens L2, a bandpass filter 125 and a third Fourier transform lens L3), a reflector 112, a spatial light modulator LCoS, a light trap 124 and an electrically controlled aperture 114; the displacement device includes an xy electrically controlled translation stage, a translation guide rail and a rotatable reflector; and the control module 400 includes a computer and its control subsystem.

[0039] In one embodiment, during holographic printing, the laser 101 emits a coherent linearly polarized laser, and its polarization state is adjusted to be consistent with the direction of the liquid crystal of the spatial light modulator LCoS through the half-wave plate 103; the laser is split into two by the first beam splitter prism 104 to form object light and reference light; the object light is adjusted to an intensity that the holographic recording material can respond quickly by the second filter 121, and after being expanded and collimated by the first spatial filter 122 and the first Fourier transform lens L1, it is split into two beams by the second beam splitter prism 123; the horizontally polarized light is directed to the spatial light modulator LCoS, and after being modulated and diffracted by the loaded hologram, an object light with three-dimensional scene information is formed, and the vertically polarized light is irradiated into the extinction structure of the light trap 124; the object light is shaped and filtered by the 4f system composed of the second Fourier transform lens L2, the third Fourier transform lens L3 and the bandpass filter 125, and finally forms an object light spot on the printing recording plane in the holographic recording device 300; Among them, the reference light is adjusted through the first filter 111 to have an intensity ratio approximately equal to that of the object light, and the range can be 1:10~10:1, with a preferred ratio of 1:1. The deflection angle of the reference light is controlled by the reflector 112, and the reference light enters the second spatial filter and the fourth Fourier transform lens L4 for beam expansion and collimation to form a reference light spot. Finally, the reference light and the object light are interference recorded on the holographic recording device 300, and the elementary hologram is overlapped and spliced ​​and printed through the xy electric-controlled translation stage. The focal length ratio parameter of the second Fourier transform lens L2 and the third Fourier transform lens L3 is used to control the zoom ratio of the final printed hologram, and the zoom ratio is the ratio of the focal length of the third Fourier transform lens L3 to the second Fourier transform lens L2. If the value is greater than 1, it is enlarged, and if it is less than 1, it is reduced.

[0040] The elementary hologram signal loaded by the spatial light modulator LCoS can be digitally filtered to control the exposure dose of the printed image in the overlapping area of ​​the elementary hologram, thereby ensuring the exposure uniformity of the hologram printing area; the CCD camera displays the overlapping position of the object light and the reference light on the holographic recording plane, thereby assisting in adjusting the size of the reference light of the printing plane of the holographic recording material; the computer controls the loading of the sub-hologram, the switching time of the electronic shutter, the movement of the xy electric-controlled translation stage, and the elimination of vibration by the phase spatial light modulator, and repeats the above steps; the holographic recording material sequentially overlaps and records the elementary object light information of the hologram, and finally synthesizes a large-size hologram, thereby completing the large-size holographic wavefront printing process.

[0041] Figure 2It is a schematic diagram of the rotation control of an xy electrically controlled translation stage and a reflector provided in an embodiment of the present application; in order to record holograms at different angles, the above-mentioned rotation control diagram includes an xy electrically controlled translation stage 201 and a reference light angle control console composed of a translation guide 115 and a rotatable reflector 112; the xy electrically controlled translation stage 201 flattens and overlaps the printed elementary hologram array by moving the holographic recording material 300 to form a complete reflector hologram with a small splicing gap; the elementary hologram is loaded with a digital filter to control the light field intensity in the printing area to ensure that the exposure dose of the entire printing plane is basically consistent; the translation guide 115 and the rotatable reflector 112 play the role of a reference light angle control console, which can accurately control the angle between the reference light and the object light in the holographic recording plane.

[0042] The position L of the reflector 112 on the translation guide rail 115 and the rotation angle of the reflector can be selected by controlling , and the adjustment of the reference light size by the electrically controlled aperture 114 can realize the recording of the hologram with reference light at any angle within a certain range.

[0043] Example 2 Figure 3 : is a flow chart of a digital filtering large-size holographic wavefront overlapping printing method provided in an embodiment of the present application; Figure 3 As shown, the following steps are included: Step S101, determining a plurality of elementary holograms to be printed respectively at a plurality of printing positions on a holographic recording medium, so as to print a large-size hologram spliced ​​from the plurality of elementary holograms on the holographic recording medium; there is partial overlap between adjacent printing positions, and there is an overlapping area between corresponding adjacent elementary holograms; each elementary hologram includes at least one overlapping area.

[0044] For example, the sizes of the elementary holograms are the same; and / or the area ratio of the overlapping regions between adjacent elementary holograms is less than 50%.

[0045] It is understandable that the above-mentioned overlapping area ratio can be designed by those skilled in the art according to actual needs. In theory, the lower the area ratio, the higher the printing efficiency, but the corresponding splicing gap elimination effect may be weaker. A better overlapping area ratio can be selected to balance the splicing gap elimination effect and printing efficiency; for example, the above-mentioned area ratio can be 10% to 30%.

[0046] As a further example, a plurality of elementary holograms may be arranged in rows and columns, see Figure 4 As shown; the adjacent elementary holograms in the upper and lower rows have an overlapping area in the row direction (such as Figure 4 In η 2× d y), which can be called the column overlap area. The adjacent elementary holograms in the left and right columns have an overlap area in the column direction (such as Figure 4 In η 1× d x ), which can be called the row overlap area. Among them, d x is the width of the elementary hologram, d y is the height of the primitive hologram, η 1. η 2 are the overlapping ratios of adjacent elementary holograms in the column direction and in the row direction, that is, the area ratio of the overlapping area in a single elementary hologram is η 1 or η 2.

[0047] Further, see Figure 5 As shown, the overlapping area of ​​each elementary hologram may include: at least one of the left column overlapping area, the right column overlapping area, the upper row overlapping area and the lower row overlapping area; there are also overlapping areas between any column overlapping area and any row overlapping area; Further, Figure 4 and Figure 5 For example, it can be seen that the elementary hologram may include multiple overlapping areas; and there may also be overlapping areas between two overlapping areas; therefore, the area where only two elementary holograms overlap can be called a primary overlapping area, and the area where two primary overlapping areas overlap can be called a secondary overlapping area.

[0048] Step S102, when printing each overlapping area of ​​the current primitive hologram, the exposure dose of each overlapping area is regulated by a digital filtering method; the digital filtering method is: controlling the exposure dose of the overlapping area to change incrementally from the first type of boundary to the second type of boundary; the first type of boundary is the boundary that only belongs to the boundary of the current primitive hologram in the boundaries of the overlapping area, and the second type of boundary is the boundary that only belongs to the boundary of its adjacent primitive hologram in the boundaries of the overlapping area; so as to reduce the diffusion consumption of the holographic recording medium at the corresponding splicing position of its adjacent primitive hologram when printing the current primitive hologram, weaken the splicing gap when the printed adjacent primitive holograms are spliced ​​through the overlapping area, and ensure that the exposure dose of each overlapping area is uniform.

[0049] In one embodiment, a plurality of elementary holograms may be distributed in rows and columns as an example for explanation, the first type of boundary in the column overlap region within the current elementary hologram is the column boundary of the current elementary hologram in the overlap region, and the second type of boundary is the column boundary of the elementary hologram in the overlap region that belongs to the adjacent column. Figure 5Taking the elementary hologram shown in the yellow area in the middle as an example, in the overlapping area with the elementary hologram adjacent to the right column direction, the first type of boundary and the second type of boundary are respectively as follows: Figure 5 As shown in the diagram; the first type of boundary in the row overlapping area within the current elementary hologram is the row boundary belonging to the current elementary hologram in the overlapping area, and the second type of boundary is the row boundary belonging to the adjacent elementary hologram in the overlapping area.

[0050] Preferably, the above digital filtering method is specifically as follows: controlling the exposure dose of the overlapping area to vary linearly or nonlinearly from the first type boundary to the second type boundary; and each time a large-size hologram is printed, the total exposure dose at each position of each overlapping area is within a preset dose range.

[0051] by Figure 6 For example, when the above digital filtering method is linearly increasing, please refer to Figure 6 As shown in (a) and (c), the two sides increase linearly from the boundary to the inside. For example, the linearly increasing action function can be expressed as: in, is the horizontal coordinate of the row arrangement direction of the elementary hologram; correspondingly, the linear digital filtering method in the column direction can refer to the row direction, which will not be described here.

[0052] Further, Figure 6 In (a), the corresponding overlapping area ratio is 50%, and in (c), the corresponding overlapping area ratio is less than 50%.

[0053] Figure 6 The digital filtering method in (b) is nonlinearly increasing, and it increases nonlinearly from both sides of the boundary. Furthermore, Figure 6 The area ratio of the corresponding overlapping area in (c) is less than 50%.

[0054] Figure 6 In (d), overlapping printing is not performed, so digital filtering is not involved. This belongs to the prior art and can be used as a comparative example to compare the effects of the embodiments of the present application.

[0055] It can be understood that if the elementary hologram includes multiple overlapping areas, the exposure dose of each overlapping area is regulated by the digital filtering method; if there are overlapping areas between at least two overlapping areas among the multiple overlapping areas, the exposure dose of each overlapping area is regulated by the digital filtering method, and the exposure dose of the overlapping area between the at least two overlapping areas is regulated by superimposing the digital filtering methods of the at least two overlapping areas.

[0056] It should be noted that, in the first overlapping area, when two adjacent elementary holograms are printed, each uses digital filtering to adjust the exposure dose once, and the first overlapping area accumulates the two printings of adjacent elementary holograms to make the total exposure dose of the first overlapping area uniform; in the second overlapping area, when four adjacent elementary holograms are printed, each uses digital filtering to adjust the exposure dose twice. Although the exposure dose adjusted twice will be lower, the comprehensive accumulation of the four printings of the four adjacent elementary holograms in the second overlapping area remains the same, which can keep the total exposure dose of the entire second overlapping area uniform.

[0057] It should be noted that each time the large-size hologram is printed, the total exposure dose at each position of each overlapping area is within the preset dose range. Further, each elementary hologram also includes: a non-overlapping area, which is an area belonging only to a single elementary hologram, and the overlapping area of ​​each elementary hologram is located around the non-overlapping area. Further preferably, the above-mentioned preset dose range is equivalent to the exposure dose of the non-overlapping area each time the large-size hologram is printed.

[0058] It is further understandable that the standard for the above exposure dose to be equivalent can be: after printing the large-size hologram once, the difference in spot intensity between the printed overlapping area and the non-overlapping area will not cause obvious visual difference to the user, and the user will not feel a sense of disconnection when viewing the printed hologram.

[0059] In a possible embodiment, the digital filtering method can be loaded on each elementary hologram to adjust the intensity of the light spots in the overlapping areas of the elementary holograms to be printed, thereby realizing the regulation of the exposure dose.

[0060] It should be noted that the above digital filtering method can be added to the elementary hologram to be printed to adjust the spot intensity of the corresponding overlapping area of ​​the hologram to be printed, so as to control the exposure dose during printing. Those skilled in the art can load the above digital filtering method in any link before printing (such as loading a light intensity adjustment device in any link before the printed light signal is incident on the holographic recording medium to adjust the exposure dose), as long as the exposure dose of the overlapping area can be controlled. Therefore, the above digital filtering loading method is not the only one.

[0061] Example 3 In one possible example, if multiple elementary holograms are printed only once according to a predetermined exposure dose, even if the exposure dose of the overlapping area is adjusted according to the above-mentioned filtering method, the basic amplitude of the dose during a single printing may still be relatively high. Therefore, a certain amount of diffusion consumption of the holographic recording medium may be introduced, resulting in a less than ideal weakening effect of the splicing gap.

[0062] Further preferably, a large-size hologram spliced ​​from a plurality of elementary holograms is printed on a holographic recording medium, comprising: repeatedly printing a plurality of elementary holograms for a plurality of times until a predetermined exposure dose is reached to obtain the printed large-size hologram; so as to weaken the exposure dose of each overlapping area of ​​a single print, and further weaken the splicing gap between adjacent elementary holograms.

[0063] It can be understood that the present application divides the predetermined exposure dose into multiple parts and repeatedly prints multiple elementary holograms to accumulate the exposure dose to the predetermined exposure dose; the advantage of this is that the exposure dose each time the elementary hologram is printed is greatly reduced. At this time, combined with the above-mentioned filtering method, the diffusion consumption of the holographic recording medium can be greatly reduced, thereby further significantly improving the weakening effect of the above-mentioned splicing gap.

[0064] like Figures 7 to 9 To pass Figure 6 Different digital filters are provided and their effects on the hologram object light spot. By loading different digital filtering methods, the brightness of the edge of the object light spot is reduced according to a certain gradient, thereby achieving an effect of high intensity in the middle and weak intensity at the edge.

[0065] in, Figure 6 Schematic diagram of exposure dose in overlapping printing process (the horizontal axis represents the position of overlapping printing in the x direction, and the vertical axis represents the exposure dose. W is the exposure dose for one cycle, n Print, is the final exposure dose required for the material); Figure 7 It is a three-dimensional schematic diagram of the digital filtering method. Figure 8 A plan view of the digital filtering method. Fig. 9 is the effect of the corresponding hologram object light spot; where white represents a value of 1, which means that the hologram light intensity is not affected (for example, the non-overlapping area is exposed with an exposure dose of W Normal printing), the black part value is 0, that is, the hologram light intensity is completely suppressed, and the gray part represents the middle value, that is, the overlapping part of the hologram, and its value gradually changes from 1 to 0.

[0066] from Figures 7 to 9 By comparison, it can be seen that Figure 6 The linear digital filtering method represented by (c) corresponds to the partially overlapping printing method. In the edge area of ​​the hologram where gaps are prone to occur, there is only one edge diffusion opportunity in one overlapping printing process, and the exposure dose of each area is the same in the overall printing. Therefore, theoretically, the printing effect may be better and the printing efficiency is taken into account.

[0067] For further example, see Fig.10 , Fig.10 (a) is in accordance with the normal process (such as Figure 6 As shown in (d), ) The kinoform reproduction result of the splicing print shows that there is a very obvious splicing gap. Fig.10 (b) is the kinoform reproduction result of non-circular overlapping stitching printing. Compared with the normal process stitching printing, the stitching gap has been partially optimized, but the gap is still visible to the naked eye. Fig.10 The distributions in (c) and (d) show the effects of eliminating the gaps in the overlapping stitching of large-scale holograms with different strategies. Figure 6 The digital filtering method shown in (c) is as follows: the former is the result of 50% overlapping printing of the digital filtering method, and the latter is the result of 20% overlapping printing of the digital filtering method; the number of cycles is 5 times, which shows that compared with Fig.10 In the non-circular overlapping stitching printing shown in (b), the stitching gap is greatly eliminated and optimized.

[0068] Preferably, if Fig.11 As shown, Fig.11 (a) is for cyclic overlapping processing only in the horizontal direction, and the vertical direction is still spliced ​​and printed according to the normal process (such as Figure 6 As shown in (d), , that is, the rows are not overlapped and printed in the traditional splicing method). From the reproduction results, it can be seen that there are still obvious splicing gaps in the vertical direction, while the horizontal splicing gaps have been optimized to a level that is invisible to the naked eye. Fig.11 (b) and (c) show the effect of eliminating the gap of large-scale hologram cyclic overlap. The number of cycles is five, and digital filtering overlap printing is performed in both horizontal and vertical directions. The former is the result of 50% cyclic overlap printing with digital filtering, and the latter is the result of 20% cyclic overlap printing with digital filtering. Fig.11 The visible stitching gaps in (b) and (c) have been greatly eliminated and optimized, almost to the point where they are invisible to the naked eye.

[0069] For example, Fig.12 As shown, it is a schematic diagram of the cyclic overlapping printing results of the large-size holographic wavefront three-dimensional hologram provided in an embodiment of the present application, the number of cycles is five, (a) shows the reproduction result of the hologram under daily lighting conditions, (b), (c), and (d) show the three-dimensional scenes of the printed hologram under three different viewing angles (observation angles) optically reconstructed under a parallel light source. It can be seen that all four images have good three-dimensional effect, and the splicing gaps are basically eliminated, and the effect is very good.

[0070] Furthermore, the application scope of the solution provided in the embodiment of the present application can also be broadened in the field of holographic optical elements, such as Fig.13The figure shows the printing imaging effect of the optical element provided in the embodiment of the present application. Through the printing system provided in the present application, the Fresnel lens phase is printed on the holographic recording material, so as to print a holographic optical element with a single-wavelength reflection lens imaging function. Fig.13 In (a), the object light wave is the white light character "HG AR", and there are two reflection images. The white light reflection image is the unscaled glass mirror reflection image, and the green light reflection image is the reflection image after optical magnification of the printed optical element. Fig.13 In (b), the object light wave is a green light badminton, and there are two reflected images, of which the closer reflected image is the unscaled glass mirror reflected image, and the farther reflected image is the reflected image after the printed optical element is optically magnified; under the action of the optical element, both object light waves are incident at 45°, reflected at 90° vertically, and have a magnifying function for the object light wave. Furthermore, through the reference light angle control, the object light wave can be selected to be incident at 15°-75°, and can choose to reduce or enlarge the function.

[0071] Fig.14 is an architecture diagram of a digital filtering large-size holographic wavefront overlap printing system provided in an embodiment of the present application; Fig.14 As shown, it includes: an optical module 1410 and a control module 1420; An optical module 1410 is used to provide an optical signal required for printing a large-size hologram on a holographic recording medium; A control module 1420 is used to cut the large-size hologram into a plurality of elementary holograms; there are overlapping areas between adjacent elementary holograms; each elementary hologram includes at least one overlapping area; The control module 1420 is further used to control the optical module to print the plurality of elementary holograms at a plurality of printing positions respectively; there are parts of adjacent printing positions, and the positions where the parts overlap correspond to the overlapping areas; The control module 1420 is also used to control the exposure dose of each overlapping area by digital filtering when printing each overlapping area of ​​the current primitive hologram; the digital filtering method is: controlling the exposure dose of the overlapping area to change incrementally from the first type of boundary to the second type of boundary; the first type of boundary is the boundary that only belongs to the boundary of the current primitive hologram in the boundaries of the overlapping area, and the second type of boundary is the boundary that only belongs to the boundary of its adjacent primitive hologram in the boundaries of the overlapping area; so as to reduce the diffusion consumption of the holographic recording medium at the corresponding splicing position of its adjacent primitive hologram when printing the current primitive hologram, weaken the splicing gap when the printed adjacent primitive holograms are spliced ​​through the overlapping area, and ensure that the exposure dose of each overlapping area is uniform.

[0072] Further preferably, the control module 1420 is also used to control the repeated printing of the multiple elementary holograms until a predetermined exposure dose is reached to obtain the printed large-size hologram; so as to weaken the exposure dose of each overlapping area of ​​a single print, and further weaken the splicing gap between adjacent elementary holograms.

[0073] It should be noted that the control module 1420 may be implemented by a processor, or by a processor controlling other devices.

[0074] It should be understood that the above-mentioned system is used to execute the methods in the above-mentioned embodiments. The implementation principles and technical effects of the corresponding modules of the system are similar to those described in the above-mentioned methods. The working process of the system can refer to the corresponding process in the above-mentioned method and will not be repeated here.

[0075] Based on the method in the above embodiment, the embodiment of the present application provides an electronic device, such as Fig.15 As shown, the electronic device may include: a processor 1510, a communication interface 1520, a memory 1530 and a communication bus 1540, wherein the processor 1510, the communication interface 1520, and the memory 1530 communicate with each other via the communication bus 1540. The processor 1510 may call the logic instructions in the memory 1530 to execute the method in the above embodiment.

[0076] In addition, the logic instructions in the above-mentioned memory 1530 can be implemented in the form of software functional units and can be stored in a computer-readable storage medium when sold or used as an independent product. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application.

[0077] Based on the method in the above embodiment, an embodiment of the present application provides a computer-readable storage medium, which stores a computer program. When the computer program runs on a processor, the processor executes the method in the above embodiment.

[0078] Based on the method in the above embodiment, an embodiment of the present application provides a computer program product. When the computer program product runs on a processor, the processor executes the method in the above embodiment.

[0079] It is understandable that the processor in the embodiment of the present application may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, transistor logic devices, hardware components or any combination thereof. The general-purpose processor may be a microprocessor or any conventional processor.

[0080] The method steps in the embodiments of the present application can be implemented by hardware or by a processor executing software instructions. The software instructions can be composed of corresponding software modules, and the software modules can be stored in random access memory (RAM), flash memory, read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, hard disks, mobile hard disks, CD-ROMs, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor so that the processor can read information from the storage medium and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and the storage medium can be located in an ASIC.

[0081] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented by software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium or transmitted through the computer-readable storage medium. The computer instructions may be transmitted from a website site, computer, server or data center to another website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrated. The available medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state drive (SSD)), etc.

[0082] It should be understood that the various numerical numbers involved in the embodiments of the present application are only used for the convenience of description and are not used to limit the scope of the embodiments of the present application.

[0083] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A digital filtering large-size holographic wavefront overlapping printing method, characterized in that: include: Determining a plurality of elementary holograms to be printed respectively at a plurality of printing positions of a holographic recording medium, so as to print a large-size hologram formed by splicing the plurality of elementary holograms on the holographic recording medium; There is partial overlap between adjacent printing positions, and there is an overlapping area between corresponding adjacent elementary holograms; each elementary hologram includes at least one overlapping area; When printing the overlapping areas of the current elementary hologram, the exposure dose of each overlapping area is regulated by a digital filtering method; the digital filtering method is: controlling the exposure dose of the overlapping area to change incrementally from the first type of boundary to the second type of boundary; the first type of boundary is the boundary that only belongs to the boundary of the current elementary hologram in the boundaries of the overlapping area, and the second type of boundary is the boundary that only belongs to the boundary of its adjacent elementary hologram in the boundaries of the overlapping area; so as to reduce the diffusion consumption of the holographic recording medium at the corresponding splicing position of its adjacent elementary hologram when printing the current elementary hologram, weaken the splicing gap when the printed adjacent elementary holograms are spliced ​​through the overlapping area, and ensure that the exposure dose of each overlapping area is uniform.

2. The method according to claim 1, characterized in that Printing a large-size hologram spliced ​​from a plurality of elementary holograms on a holographic recording medium comprises: the plurality of elementary holograms are repeatedly printed for a plurality of times until a predetermined exposure dose is reached to obtain the printed large-size hologram; so as to weaken the exposure dose of each overlapping area of ​​a single print, and further weaken the splicing gap between adjacent elementary holograms.

3. The method according to claim 1 or 2, characterized in that: If the elementary hologram includes a plurality of overlapping regions, the exposure dose is regulated by the digital filtering method in each overlapping region; And / or if the elementary hologram includes multiple overlapping areas, and there are overlapping areas between at least two overlapping areas among the multiple overlapping areas, then the exposure dose of each overlapping area is regulated by the digital filtering method, and the exposure dose of the overlapping area between the at least two overlapping areas is regulated by the superposition of the digital filtering methods of the at least two overlapping areas.

4. The method according to claim 1 or 2, characterized in that: The digital filtering method is specifically as follows: controlling the exposure dose of the overlapping area to change linearly or nonlinearly from the first type boundary to the second type boundary; and each time the large-size hologram is printed, the total exposure dose at each position of each overlapping area is within a preset dose range.

5. The method according to claim 4, characterized in that Each elementary hologram further comprises: a non-overlapping region, wherein the non-overlapping region is a region belonging only to a single elementary hologram; and / or The preset dose range is equivalent to the exposure dose of the non-overlapping area each time the large-size hologram is printed.

6. The method according to claim 1 or 2, characterized in that: The plurality of elementary holograms are distributed in rows and columns; the elementary holograms adjacent to each other in the upper and lower rows have an overlapping area in the row direction, and the elementary holograms adjacent to each other in the left and right columns have an overlapping area in the column direction; The overlapping area of ​​each elementary hologram includes at least one of a left column overlapping area, a right column overlapping area, an upper row overlapping area, and a lower row overlapping area; There are also overlapping areas between any column overlap area and any row overlap area; The first type of boundary in the column overlap region within the current elementary hologram is the column boundary in the overlap region belonging to the current elementary hologram, and the second type of boundary is the column boundary in the overlap region belonging to the column adjacent elementary hologram; The first type of boundary in the row overlapping area within the current elementary hologram is the row boundary in the overlapping area belonging to the current elementary hologram, and the second type of boundary is the row boundary in the overlapping area belonging to the row adjacent elementary hologram.

7. The method according to claim 1 or 2, characterized in that: The sizes of the elementary holograms are the same; and / or the area ratio of the overlapping regions between adjacent elementary holograms is less than 50%; And / or the digital filtering method is loaded on each elementary hologram, so as to adjust the light spot intensity of each overlapping area of ​​the elementary hologram to be printed, so as to realize the regulation of the exposure dose.

8. A digital filtering large-size holographic wavefront overlapping printing system, characterized in that: include: Optical module and control module; The optical module is used to provide the optical signal required for printing a large-size hologram on a holographic recording medium; The control module is used to cut the large-size hologram into a plurality of elementary holograms; there are overlapping areas between adjacent elementary holograms; each elementary hologram includes at least one overlapping area; The control module is further used to control the optical module to print the plurality of elementary holograms at a plurality of printing positions respectively; there are parts of adjacent printing positions, and the positions where the parts overlap correspond to the overlapping areas; The control module is also used to control the exposure dose of each overlapping area by digital filtering when printing each overlapping area of ​​the current elementary hologram; the digital filtering method is: controlling the exposure dose of the overlapping area to change incrementally from the first type of boundary to the second type of boundary; the first type of boundary is the boundary that only belongs to the boundary of the current elementary hologram in the boundaries of the overlapping area, and the second type of boundary is the boundary that only belongs to the boundary of its adjacent elementary hologram in the boundaries of the overlapping area; so as to reduce the diffusion consumption of the holographic recording medium at the corresponding splicing position of its adjacent elementary hologram when printing the current elementary hologram, weaken the splicing gap when the printed adjacent elementary holograms are spliced ​​through the overlapping area, and ensure that the exposure dose of each overlapping area is uniform.

9. The system according to claim 8, characterized in that The control module is also used to control the repeated printing of the multiple elementary holograms until a predetermined exposure dose is reached to obtain the printed large-size hologram, so as to weaken the exposure dose of each overlapping area of ​​a single print and further weaken the splicing gap between adjacent elementary holograms.

10. An electronic device, characterized in that: include: at least one memory for storing a computer program; At least one processor is used to execute the program stored in the memory. When the program stored in the memory is executed, the processor is used to execute the method according to any one of claims 1 to 7.

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