Stretching strain regulated grating parameter and single mold multiplexing method

Abstract

The present application belongs to the field of optical design and precision glass mold pressing processing, and particularly relates to a tensile strain regulated grating parameter and single-mold multiplexing method. The method comprises the following steps: step 1, based on multi-image display requirements, a mapping model of color structured light field and grating parameters is established through pixel-level optical simulation; step 2, a mold critical elongation threshold is determined in combination with finite element analysis, a grating parameter transformation algorithm is constructed, and hidden images are triggered to trigger the hidden / visible conversion under the preset tensile strain; step 3, micro / nano processing technology is used to process the pre-designed precision grating master on the surface of a hard mold; step 4, a stretchable mold is formed by flexible material transfer, the tensile strain is regulated to dynamically change the grating parameters during mold pressing, and single-mold transfer of multiple-state optical structures is realized. Through dynamic parameter mapping and flexible mold deformation control, the present application overcomes the problems of low switching efficiency and high cost of multiple molds, and provides a new path for micro / nano structure manufacturing.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of optical design and precision glass mold pressing processing, and particularly relates to a tensile strain regulated grating parameter and single-mold multiplexing method. BACKGROUND

[0002] Metal or hard mold surface replication technology plays a crucial role in modern industrial manufacturing. With the continuous development of technology, the demand for surface structure replication technology is increasing. However, metal or hard mold surface replication technology has significant drawbacks in structural color regulation. Structural color regulation relies on precise nanostructure design, but the dynamic regulation capability of metal or hard mold surface is limited, and once formed, it is difficult to change the color characteristics, limiting its application in dynamic display and real-time color regulation. These technical bottlenecks result in low manufacturing efficiency and rising costs, making it difficult to meet the demand for high precision and high performance in modern manufacturing. In response to these challenges, many researchers are committed to exploring new metal surface structure replication technology. Among them, flexible materials as a new type of material with excellent performance have shown great potential in metal or hard mold surface structure replication. Flexible materials have good flexibility and replicability, and can accurately replicate the microstructure of the metal or hard mold surface. At the same time, flexible materials also have excellent chemical stability and thermal stability, and can maintain stable performance in various harsh environments. Therefore, flexible materials have broad application prospects in metal surface structure replication technology.

[0003] In the field of materials science, transparent media including glass and polymer as two important material types are widely used in various aspects of our daily life. However, these two materials often face challenges in color processing and surface image processing. Glass has high transparency and high hardness, and plays an important role in doors and windows, utensils and other fields, but its surface processing is difficult, especially in coloring and image pattern processing. As an inorganic non-metallic material, glass has a stable chemical structure, making it difficult for conventional pigments to adhere uniformly to its surface. Even if the pigments are melted into the glass interior through complex processes such as high-temperature melting, it is often difficult to achieve the desired color effect. Similarly, polymers are widely used in plastic packaging, coating materials and other fields due to their excellent flexibility and processing performance, but the coloring process is often unsatisfactory. Although the surface processing performance of polymers is relatively good, the long molecular chains of polymers tend to form a network structure, making it difficult for pigment molecules to penetrate into the interior. Therefore, special processes and pigments are often required to ensure bright and durable colors for polymers. At the same time, factors such as surface tension and polarity of polymers also affect the coloring effect, making the coloring process relatively complex.

[0004] The mold pressing equipment has significant advantages in flexible template replication process, can realize micron-level precision control, and ensure that the replicated pattern is highly consistent with the original design. Its high efficiency is another highlight. Compared with traditional manual replication, mold pressing equipment can greatly shorten the replication cycle and improve production efficiency. In addition, the mold pressing equipment is easy to operate and has strong stability. After simple training, the operator can operate it. During the replication process, the performance can be kept stable, and the production interruption caused by equipment failure can be reduced.

[0005] However, the mold pressing equipment also has some disadvantages. The mold manufacturing is complex and costly, especially for large and complex geometric molds. In addition, traditional mold pressing usually only realizes the replication of a single pattern, which is difficult to meet the needs of multiple patterns or dynamic patterns. To solve these problems, we propose a method of stretching strain regulation of grating parameters and single mold multiplexing. This technology can realize the switching of multiple patterns on a single mold. By stretching operation, the pattern can be triggered to appear or hide, which significantly improves the multiplexing and flexibility of the mold. SUMMARY

[0006] To solve the above problems, the purpose of the present application is to provide a method of stretching strain regulation of grating parameters and single mold multiplexing. By adjusting the cutting parameters, two or more micro / nano grating structures are embedded in a single mold. The mold can present different images in the relaxed and stretched states. Further, the device replicates these images on the surface of transparent medium materials such as glass or polymers through mold pressing technology, realizing the multiplexing and efficient manufacturing of multiple optical effects embedded in a single mold surface. This not only reduces the number of molds and production costs, but also provides a new idea and method for the manufacturing of complex micro / nano structures on the surface of transparent medium materials.

[0007] To achieve the above purpose, the technical solution adopted by the present application is:

[0008] A method of stretching strain regulation of grating parameters and single mold multiplexing, comprising the following steps,

[0009] Step 1: Based on the demand for multi-image display, a mapping model of color structured light field and grating parameters is established through pixel-level optical simulation;

[0010] Step 2: Combine finite element analysis to determine the critical elongation threshold of the mold, and construct a grating parameter transformation algorithm to trigger the hidden image to appear / hidden conversion under the preset stretching strain;

[0011] Step 3: Use micro / nano processing technology to process the pre-designed precision grating master on the surface of a hard mold;

[0012] Step 4: Form a stretchable mold by transferring flexible materials. When mold pressing, the stretching strain is dynamically changed to regulate the grating parameters, realizing the transfer of multiple optical structures by a single mold.

[0013] As preferred, in step 1, the simulation and calculation of the color image's grating structure parameters include:

[0014] Step 101, first select two or more images that need to be embedded, and process these images to the appropriate size to regulate the number of processing pixels. This process is achieved through image preprocessing algorithms, aiming to reduce computational complexity while preserving key color and structural information of the image. Then, the pixel color information of the image is extracted through code calculation, including Hue hue value or RGB color value. These color information is the basis for subsequent grating structure design, used to determine the structure light grating structure corresponding to each pixel color.

[0015] Step 102, according to the extracted pixel color information, it is converted into the corresponding structure light wavelength. This conversion is based on optical principles, mapping the color information of the image to the physical parameters of the grating structure. Specifically, by combining color information with the diffraction characteristics of the grating through an optical model, the required grating wavelength for each pixel is determined. The conversion formula is:

[0016] ;

[0017] Where, represents the grating wavelength, is the conversion function based on the optical model, which maps the color information (Hue or RGB) to the corresponding grating wavelength;

[0018] Step 103, based on the grating diffraction equation, the grating constant, grating depth and grating period corresponding to each pixel are calculated through the optical diffraction model:

[0019] ;

[0020] In the formula, and represent the incident angle and diffraction angle respectively, is the diffraction order, is the grating pitch.

[0021] Step 104, in order to determine that the color image can be correctly presented, the grating diffraction process in the color pixel is simulated and the light intensity is calculated:

[0022] ;

[0023] Where is the light intensity of the incident light on the grating surface, is the spectral power reflectivity of the smooth mirror metal surface, , represent the combined vibration parameters of the main working surface and auxiliary working surface respectively, , These represent the phase difference in single-grating dual-working-plane interference and the phase difference in multi-grating interference, respectively. It is the number of surface gratings. It represents the amplitude spectrum of the incident light wave. Using this formula, the diffracted light intensity of each pixel under a specific grating structure can be accurately calculated, thereby optimizing the grating parameters to achieve the best optical effect.

[0024] Step 105: Using the CIE 1931 color matching function, the spectral intensity in the visible spectrum is converted into XYZ three-color coordinates, and the raster parameters are further optimized to match the target color.

[0025] ;

[0026] ;

[0027] ;

[0028] ;

[0029] ;

[0030] in , , It is the calibration color function for a 2° standard observer. and These are the upper and lower limits of the visible spectrum. These represent spectral intensity. Using these formulas, spectral intensity can be converted into XYZ three-color coordinates, allowing for further optimization of grating parameters to match the target color and ensure that the optical effect of the image after molding is consistent with the design.

[0031] Step 106: Integrate the calculated grating parameters into a grating structure design drawing, which will serve as the basis for subsequent micro / nano structure processing, ensuring that the grating structure on the mold surface can accurately achieve the predetermined optical effect.

[0032] Preferably, in step 2, the method for integrating and calculating the raster parameters for the image in the initial hidden state includes:

[0033] Step 201: Subdivide the processing area size, clarify the pixel dimensions of the displayed and hidden images in the initial state, and execute the pixel position cross-arrangement design. When designing the grating structure, the grating is divided into two parts:

[0034] For the image displayed in the initial state, the grating spacing of the corresponding pixels is directly processed according to the above calculation method, and the generated structured light is precisely controlled within the visible light wavelength range to achieve the display of the predetermined image in the unstretched state;

[0035] For the image hidden in the initial state, according to the uniform deformation mechanism of the medium, the initial pitch of the corresponding pixel grating structure needs to be adjusted by transformation, and the grating pitch adopted by micro / nano processing is

[0036] ;

[0037] Wherein is the grating pitch after transformation adjustment, is the calculated grating pitch, is the trigger image stretch rate.

[0038] Through this adjustment, it is ensured that in the unstretched state, the structured light generated by the grating structure is not in the visible light window range, and the other predetermined image can be completely hidden; when the stretch rate reaches the trigger threshold , the grating parameters after stretching deformation are just diffracted to form colored visible light, achieving the effect of triggering the hidden picture, and for the image displayed without stretching, the grating parameters do not meet the visible light diffraction window at this time, thereby achieving the hiding effect.

[0039] At the same time, by accurately controlling the processing parameters, the design of the above grating pitch is realized, the hiding and appearing of the image in the stretching process is realized, and different trigger stretch rates can be set for multiple images , realizing the animation process of alternating appearance and hiding of multiple images.

[0040] Step 202, based on the elongation rate of the stretching trigger point, the grating structure in the stretched state is simulated according to the simulation process in step 1, and the grating constant is adjusted to ensure that the image is converted between hidden and visible during stretching. Through simulation analysis, the deformation law of the grating in the stretching process is determined, and the grating parameters are optimized to realize the predetermined optical effect.

[0041] Step 203, simulation verification is performed on the adjusted grating parameters to ensure that the grating structure can accurately realize the predetermined optical effect before and after stretching. The simulation verification includes analysis of grating diffraction efficiency, light intensity distribution and color matching to ensure that the image can be correctly displayed during stretching.

[0042] Step 204, integrate the optimized grating parameters into a complete grating structure design diagram for subsequent micro / nano processing, to ensure that the mold can realize the hidden and visible state conversion of the image during stretching.

[0043] As preferred, in step 3, the method of processing the grating structure on the surface of the hard mold by micro / nano processing technology includes:

[0044] Step 301, select metal or hard non-metal material as the mold base, and precisely process the mold to form micro-nano gratings with predetermined images and sizes.

[0045] Step 302, according to the design requirements of the grating structure, select vibration cutting, femtosecond laser direct writing or electron beam exposure micro-nano processing technology to process micro-nano grating structure on the mold surface.

[0046] Step 303, during the processing, the processing precision and surface roughness need to be strictly controlled to ensure the structural integrity and optical performance of the micro-nano grating. After processing, clean and inspect the mold to remove impurities and defects on the surface and ensure the quality of the mold.

[0047] Step 304, by adjusting the pitch and arrangement of the grating structure, different image display effects such as dynamic transformation and stereoscopic effect can be achieved. At the same time, by changing the material and shape of the micro-nano structure, the optical performance and durability of the mold can be further optimized.

[0048] As preferred, in step 4, the method of transferring the grating structure on the mold using flexible material includes:

[0049] Step 411, select a flexible high polymer material with a tensile rate matching the preset trigger tensile rate;

[0050] Step 412, clean the mold surface;

[0051] Step 413, apply the prepolymer to the surface of the micro-nano grating structure of the hard mold;

[0052] Step 414, control the thickness of the coating layer;

[0053] Step 415, cure the prepolymer at room temperature or under slight heating;

[0054] Step 416, peel off the cured flexible material layer to obtain a flexible mold with micro-nano grating structure.

[0055] As preferred, in step 4, the method of transferring the grating structure on the mold by mold pressing includes:

[0056] Step 421, use hot pressing, cold pressing or ultraviolet curing pressing technology;

[0057] Step 422, control the mold pressing temperature, pressure and time;

[0058] Step 432, for the original state display image, place the transparent medium substrate on the unstretched flexible mold; for the hidden image, stretch the flexible mold to the trigger tensile rate, and then place the transparent medium substrate on it;

[0059] Step 442, pressurize the substrate using a molding machine under appropriate temperature and pressure conditions;

[0060] Step 452, slowly release the pressure of the molding machine and gradually cool the substrate;

[0061] Step 462, take out the replicated transparent medium substrate from the flexible mold, check the quality of the replicated image, and use an optical microscope or other imaging equipment to evaluate the replicated image;

[0062] Step 472, if necessary, repeat steps 411 to 462 to verify the repeatability and reliability of the experimental results.

[0063] The beneficial effects of using the present application are:

[0064] (1) The method provided in the embodiments of the present application uses precise theoretical calculations and simulation to achieve efficient manufacturing of multiple optical effects embedded in a single mold surface, allowing the mold to maintain stable image display effects and excellent optical performance during long-term use.

[0065] (2) In the embodiments, the use of micro / nano processing technology and flexible materials allows the mold to reversibly switch image styles during stretching and relaxation, achieving different image display effects such as dynamic transformation and stereoscopic effects.

[0066] (3) The mold manufacturing method of the present application is simple, low cost, and suitable for large-scale production, making it suitable for the manufacturing of various optical devices and greatly expanding the application field of optical molds. BRIEF DESCRIPTION OF DRAWINGS

[0067] Figure 1 A method flowchart of a stretching strain regulated grating parameter and single-mold multiplexing method provided by the embodiments of the present application is shown;

[0068] Figure 2 A schematic diagram of surface grating topography and color distribution provided by the embodiments of the present application is shown;

[0069] Figure 3 A schematic diagram of flexible template retransfer and presentation of two images before and after stretching provided by the embodiments of the present application is shown;

[0070] Figure 4 A schematic diagram of surface grating changes during the stretching process of the flexible template provided by the embodiments of the present application is shown;

[0071] Figure 5 A schematic diagram of transparent medium molding copy images before and after stretching provided by the embodiments of the present application is shown. DETAILED DESCRIPTION

[0072] In order to make the purpose, technical scheme and advantages of the technical solution clearer and more intelligible, the technical solution will be further described in detail below in combination with specific embodiments. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the technical solution.

[0073] Embodiment one,

[0074] Please refer to Figure 1 , Figure 1 The process flow chart of the process method for embedding two or more micro / nano structure patterns in a single flexible mold surface provided by the embodiment of the application, realizing different optical effects of the mold pressing forming surface through stretching trigger and glass mold pressing process, the method comprises:

[0075] S101, based on the multi-image display requirement, a mapping model of color structured light field and grating parameters is established through pixel-level optical simulation.

[0076] S102, the critical elongation threshold of the mold is determined in combination with finite element analysis, a grating parameter transformation algorithm is constructed, and the hidden image is triggered to switch between hidden and visible states under the preset stretching strain.

[0077] S103, a precision grating master is processed on the surface of a hard mold by using micro / nano processing technology.

[0078] S104, a stretchable mold is formed by transferring flexible materials, and the grating parameters are dynamically changed by adjusting the stretching strain during mold pressing, realizing single-mold transfer of multiple-state optical structures.

[0079] Embodiment two, the simulation and calculation of the grating structure parameters of the color image include:

[0080] Step 201, first, select two or more images to be embedded, and process these images to appropriate size to regulate the number of processed pixels. This process is realized by an image preprocessing algorithm, aiming to reduce the calculation complexity while retaining the key color and structure information of the image. Then, the pixel color information of the image is extracted by code calculation, including Hue hue value or RGB color value. These color information is the basis for subsequent grating structure design, used to determine the structure grating structure corresponding to each pixel color.

[0081] Step 202, according to the extracted pixel color information, it is converted into corresponding structure light wavelength. This conversion is based on optical principles, mapping the color information of the image to the physical parameters of the grating structure. Specifically, by combining the color information with the diffraction characteristics of the grating through an optical model, the required grating wavelength for each pixel is determined. The conversion formula is:

[0082] ; (1)

[0083] wherein, denotes the grating wavelength, denotes the hue information, mapping the color information to the corresponding grating wavelength.

[0084] Step 203, based on the grating diffraction equation, calculate the grating constant, grating depth and grating period corresponding to each pixel through the optical diffraction model, the interval distance between two adjacent gratings in the machining direction is given by:

[0085] ; (2)

[0086] wherein, and represent the incident angle and diffraction angle respectively, is the diffraction order, is the grating pitch.

[0087] Step 204, during the machining process, the shape and distribution of the periodic image generated on the machined surface are functions of the machining tool geometry and process parameters:

[0088] ; (3)

[0089] wherein, is the cutting speed, is the vibration frequency.

[0090] Step 205, in order to ensure that the color image can be correctly displayed, simulate the grating diffraction process in the color pixel and calculate the light intensity:

[0091] ; (4)

[0092] wherein is the light intensity of the incident light on the grating surface, is the spectral power reflectance of the smooth mirror metal surface, , represent the combined vibration parameters of the main working surface and the auxiliary working surface respectively, , represent the phase difference of single-grating double-working surface interference and the phase difference of multi-grating interference respectively, is the number of surface gratings, is the amplitude spectrum of the incident light wave. Through this formula, the diffraction light intensity of each pixel under a specific grating structure can be accurately calculated, so as to optimize the grating parameters to achieve the best optical effect.

[0093] Step 206, use CIE 1931 color matching function to convert the spectral intensity in the visible spectral range to XYZ tricolor coordinates, further optimize the grating parameters to match the target color:

[0094] (5)

[0095] (6)

[0096] (7)

[0097] (8)

[0098] (9)

[0099] where , , is the calibration color function of the 2° standard observer, and are the upper and lower limits of the visible spectrum, represents the spectral intensity. Through these formulas, the spectral intensity can be converted into XYZ tristimulus coordinates, and the grating parameters are further optimized to match the target color, ensuring that the optical effect of the image after molding is consistent with the design.

[0100] Step 207, integrate the calculated grating parameters into the grating structure design, which will serve as the basis for subsequent micro / nano processing, ensuring that the grating structure on the mold surface can accurately achieve the predetermined optical effect.

[0101] The whole process from extracting pixel color information of color images to optimizing grating parameters is described in detail by the method of Example Two. This process includes calculating the wavelength of the structured light, determining the grating pitch, simulating the diffraction light intensity of the grating, and optimizing the grating parameters using the CIE1931 color matching function, finally generating the grating structure design, providing accurate guidance for micro / nano processing.

[0102] Example Three, for images with initial hidden states, the method of integrating and calculating grating parameters includes:

[0103] Step 301, subdivide the processing area size, clearly define the pixel size of the displayed and hidden images in the initial state, and perform pixel position cross arrangement design. When designing the grating structure, the grating is divided into two parts:

[0104] For images displayed in the initial state, the grating pitch of the corresponding pixels is directly processed according to the above calculation method, and the structured light generated is accurately controlled within the visible light wavelength range to realize the appearance of the predetermined image in the unstretched state;

[0105] For images hidden in the initial state, according to the uniform deformation mechanism of the medium, the initial pitch of the grating structure corresponding to the pixels needs to be transformed and adjusted, and the grating pitch used in micro / nano processing is

[0106] ; (10)

[0107] wherein is the adjusted grating pitch after transformation, is the calculated grating pitch, is the trigger image stretch ratio.

[0108] Through this adjustment, it is ensured that in the non-stretched state, the structured light generated by the grating structure is not in the visible light window range, and the other predetermined image can be completely hidden; when the stretch ratio reaches the trigger threshold , the grating parameters after deformation by stretching are just diffracted to form colored visible light, achieving the effect of triggering the hidden picture, and for the image displayed without stretching, the grating parameters do not meet the visible light diffraction window at this time, thereby achieving the hiding effect.

[0109] At the same time, by precisely controlling the processing parameters, the design of the above grating pitch is realized, the hiding and appearing of the image in the stretching process is realized, and different trigger stretch ratios can be set for multiple images to realize the alternating appearance and hiding of multiple images. The surface grating topography and color change are referred to Figure 2 .

[0110] Step 302, based on the elongation ratio of the stretching trigger point, the topography change of the grating structure in the stretched state is simulated according to the simulation process in step 1, and the grating constant is adjusted to ensure that the image is converted between appearing and disappearing in the stretching process. Through simulation analysis, the deformation law of the grating in the stretching process is determined, and the grating parameters are optimized to realize the predetermined optical effect.

[0111] Step 303, the adjusted grating parameters are simulated and verified according to the simulation steps of embodiment two, to ensure that the grating structure can accurately realize the predetermined optical effect before and after stretching. The simulation verification includes analysis of grating diffraction efficiency, light intensity distribution and color matching, to ensure that the image can correctly appear in the stretching process.

[0112] Step 304, integrate the optimized grating parameters into a complete grating structure design diagram for subsequent micro / nano processing, to ensure that the mold can realize the appearing and disappearing state conversion of the image in the stretching process.

[0113] Embodiment three proposes a grating parameter integration calculation method for an initial hidden state image. By subdividing the processing area, designing a cross grating structure, and adjusting the grating parameters based on the stretching trigger point and the medium deformation mechanism, a complete grating structure design diagram is finally generated, ensuring that the mold realizes the appearing and disappearing state conversion of the image in the stretching process.

[0114] Example Four, a method for processing color images on the surface of a hard mold using micro / nano processing technology includes:

[0115] Step 401, select a metal or hard non-metal material as the mold substrate, and precisely process the mold to form a micro / nano grating with a predetermined image and size.

[0116] Step 402, according to the design requirements of the grating structure, select vibration cutting, femtosecond laser direct writing or electron beam exposure micro / nano processing technology to process the micro / nano grating structure on the surface of the mold.

[0117] Step 403, during the processing, the processing precision and surface roughness need to be strictly controlled to ensure the structural integrity and optical performance of the micro / nano grating. After processing, the mold is cleaned and inspected to remove impurities and defects on the surface and ensure the quality of the mold.

[0118] Step 404, by adjusting the pitch and arrangement of the grating structure, different image display effects such as dynamic transformation and stereoscopic effect can be achieved. At the same time, by changing the material and shape of the micro / nano structure, the optical performance and durability of the mold can be further optimized.

[0119] Through the method of this example four, the micro / nano grating structure with two image styles embedded on the surface of the metal mold is successfully processed, and the appearance and hiding of the image are correctly controlled, thereby realizing the change of color image, which provides a key mold technology foundation for the subsequent precise coloring process on transparent medium materials.

[0120] Example Five, a method for copying the grating structure on the mold using flexible material includes:

[0121] Step 501, the flexible material is a high polymer material with specific tensile rate and optical properties to realize reversible switching of image style during stretching and relaxation.

[0122] Step 502, clean the mold surface to remove any possible contaminants to ensure the replication quality.

[0123] In this step, the cleaning process can use an ultrasonic cleaner with appropriate solvents such as isopropyl alcohol or deionized water to ensure that the mold surface is free of oil, dust or other impurities.

[0124] Step 503, apply the prepolymer to the surface of the micro / nano grating structure of the metal mold.

[0125] In this step, the thickness of the coating layer needs to be precisely controlled, which can be achieved by using coating knives, screen printing or spin coating, etc.

[0126] At the same time, ensure that the prepolymer uniformly covers the mold surface during the coating process to avoid the generation of bubbles and defects.

[0127] Step 504, under room temperature or slight heating conditions, the prepolymer is fully cured to ensure complete structural replication.

[0128] In this step, the curing process is usually placed at room temperature for several hours or accelerated by an oven at a temperature of 80°C.

[0129] Step 505, gently peel off the cured flexible material layer to separate the flexible material surface layer with micro-nano grating structure from the metal mold.

[0130] Step 506, check the replicated flexible material surface layer to confirm the integrity and precision of the micro-nano grating structure.

[0131] In this step, optical microscopy, scanning electron microscopy (SEM) or other surface analysis techniques can be used.

[0132] Step 507, test the performance of the replicated flexible surface layer, including tensile properties, optical properties, etc., to ensure that it meets the application requirements.

[0133] Step 508, observe the appearance and hiding of the image during stretching.

[0134] In this step, during the stretching process, the un-stretched image grating pitch gradually increases, according to the grating equation formula (2), the pitch is proportional to the wavelength, and the wavelength gradually increases, making the image gradually disappear, as shown in Figure 3 .

[0135] At the same time, the change of the flexible material surface grating during stretching is shown in Figure 4 .

[0136] Through the method of this embodiment five, the micro-nano grating structure on the metal mold is transferred to the prepolymer surface layer by replication technology, and the accurate replication of micro-nano structure is successfully realized. This replication technology not only has high repeatability and stability, but also can preserve the microstructure and characteristics of the metal surface, providing a high-quality template for subsequent mold pressing equipment replication.

[0137] Embodiment six, the method of transferring the grating structure on the mold pressing mold by mold pressing includes:

[0138] Step 601, the mold pressing technology includes hot pressing, cold pressing or ultraviolet curing mold pressing, etc.

[0139] Step 602, prepare a transparent medium substrate, select appropriate size and shape to adapt to the mold pressing process.

[0140] In this step, the substrate surface should be smooth, clean, free of scratches or defects to ensure the quality of image reproduction.

[0141] Step 603: If the original state of the displayed picture is to be copied, place the transparent medium substrate directly on the flexible mold; if the hidden picture is to be copied, stretch the flexible mold to trigger the stretch ratio to make the hidden image trigger to the display state, and then place the transparent medium substrate on the flexible mold. In this step, under appropriate temperature and pressure conditions, use a molding machine to press the substrate, so that the color image structure on the surface of the flexible mold is transferred to the surface of the substrate.

[0142] Step 604: Maintain a certain pressure and temperature until the color image is completely copied to the transparent medium surface.

[0143] Step 605: Slowly release the pressure of the molding machine, and gradually cool the substrate to prevent image distortion or damage caused by rapid temperature change.

[0144] Step 606: Gently remove the copied transparent medium substrate from the flexible mold and check the quality of the copied image.

[0145] At the same time, use an optical microscope or other imaging equipment to evaluate the copied image to ensure color accuracy and image clarity.

[0146] Here, the process of molding and copying the two images before and after stretching the transparent medium with a flexible template is shown in Figure 5 .

[0147] Step 607: Post-processing of the copied color image, such as curing, hardening or adding protective coating, to improve the durability and environmental adaptability of the image.

[0148] Step 608: Performance testing of the final product, including color stability, scratch resistance, weather resistance, etc., to ensure its reliability in the expected application environment.

[0149] Step 609: According to the test results, optimize the molding process to improve production efficiency and reduce costs while maintaining or improving product performance.

[0150] The above is only the preferred embodiment of the present application. For those skilled in the art, according to the technical content of the present application, many changes can be made in the specific implementation and application range, as long as these changes do not deviate from the concept of the present application, they all belong to the protection scope of the present patent.

Claims

1. A method for controlling the parameters of a tensile strain grating and reusing a single mold, characterized in that: The method comprises the following steps, Step 1, based on multi-image display requirements, a mapping model of color structured light field and grating parameters is established by pixel-level optical simulation; Step 2, the critical elongation threshold of the mold is determined by combining finite element analysis, and a grating parameter transformation algorithm is constructed to trigger the display / hidden conversion of the hidden image at a preset stretching strain; Step 3, a micro / nano processing technology is used to process the pre-designed precision grating master on the surface of the hard mold; Step 4, a stretchable mold is formed by flexible material transfer, and the stretching strain is dynamically changed to regulate the grating parameters during mold pressing, thereby realizing single-mold transfer of multiple-state optical structures; In step 1, the simulation and calculation of the grating structure parameters of the color image include: Step 101, select two or more images to be embedded, process the image size to regulate the number of processed pixels, and extract the pixel color information of the image, which includes hue value or RGB color value; Step 102, according to the pixel color information, the color information is mapped to the corresponding grating wavelength through the optical model, and the conversion formula is: ； wherein, represents the grating wavelength, is a conversion function based on an optical model that maps color information (Hue or RGB) to the corresponding grating wavelength; Step 103, based on the grating diffraction equation, the grating constant corresponding to each pixel is calculated through the optical diffraction model: ； wherein and represent the incident angle and the diffraction angle, respectively, is the diffraction order, is the grating pitch; Step 104, simulate the grating diffraction process of the color pixel and calculate the light intensity: ； wherein is the light intensity of the incident light on the grating surface, is the spectral power reflectance of a smooth mirror metal surface, , represent the combined vibration parameters of the main working surface and the auxiliary working surface, respectively, , represent the phase difference of the single-grating double-surface interference and the phase difference of the multi-grating interference, respectively, is the number of surface gratings, is the amplitude spectrum of the incident light wave; Step 105, use CIE 1931 color matching function to convert the spectral intensity in the visible spectrum range into XYZ three-color coordinates: ； ； ； ； ； wherein , , is a calibration color function for a 2° standard observer, and are upper and lower limits of the visible spectrum, denotes spectral intensity; Step 106, integrate the calculated grating parameters into a grating structure design diagram.

2. The stretch strain regulated grating parameter and single-mold multiplexing method according to claim 1, characterized in that: In step 2, the transformation calculation of the grating parameters of the image in the initial hidden state includes: Step 201, subdivide the processing area size, determine the pixel size of the display and hidden image in the initial state, and perform pixel position cross arrangement design; the grating pitch of the pixels corresponding to the display image is calculated according to the method of claim 1; the grating pitch of the pixels corresponding to the hidden image is transformed and adjusted according to the uniform deformation mechanism of the medium: ； wherein is the transformed adjusted raster pitch, is the calculated raster pitch, is the trigger image stretch ratio; Step 202, based on the preset stretching rate, simulate the morphology change of the grating structure in the stretching state according to the simulation process in step 1 of claim 1, and adjust the grating constant; Step 203, simulate and verify the adjusted grating parameters, which include analysis of grating diffraction efficiency, light intensity distribution and color matching; Step 204, integrate the optimized grating parameters to generate a complete grating structure design diagram.

3. The stretch strain regulated grating parameter and single-mold multiplexing method according to claim 2, characterized in that: In step 3, the method of processing the grating structure on the surface of the hard mold by using micro / nano processing technology includes: Step 301, select metal or hard non-metal as the mold base, and precisely process the mold; Step 302, according to the design requirements of the grating structure, select vibration cutting, femtosecond laser direct writing or electron beam exposure micro / nano processing technology to process micro / nano grating structure on the surface of the mold; Step 303, control the processing precision and surface roughness during processing; Step 304, adjusting the interval and arrangement of the grating structure according to the grating structure design diagram.

4. The method of claim 1, wherein the method is characterized in that: In step 4, the method of using a flexible material to transfer the grating structure on the mold includes: Step 411, selecting a flexible high polymer material with a stretching rate matching the preset trigger stretching rate; Step 412, cleaning the mold surface; Step 413, coating the prepolymer on the micro-nano grating structure surface of the hard mold; Step 414, controlling the thickness of the coating layer; Step 415, curing the prepolymer under room temperature or slight heating conditions; Step 416, peeling off the cured flexible material layer to obtain a flexible mold with micro-nano grating structure.

5. The method of claim 4, wherein the method is characterized in that: In step 4, the method of transferring the grating structure on the flexible mold by mold pressing includes: Step 421, using hot-pressing, cold-pressing or ultraviolet curing mold pressing technology; Step 422, controlling the mold pressing temperature, pressure and time; Step 432, for the original state display image, place the transparent dielectric substrate on the unstretched flexible mold; for the hidden image, stretch the flexible mold to trigger the stretch ratio Then, place the transparent dielectric substrate on it again; Step 442, using a mold press to press the substrate under appropriate temperature and pressure conditions; Step 452, slowly release the pressure of the mold press and gradually cool the substrate; Step 462, taking out the copied transparent medium substrate from the flexible mold, checking the quality of the copied image, and using an optical microscope or other imaging equipment to evaluate the copied image; Step 472, if necessary, repeating steps 411 to 462 to verify the repeatability and reliability of the experimental results.

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