Tensile strain regulation and control grating parameter and single die multiplexing method

Abstract

The invention belongs to the field of optical design and precision glass mold pressing processing, and particularly relates to a method for regulating and controlling grating parameters through tensile strain and multiplexing a single mold. Comprising the following steps: step 1, based on a multi-image display requirement, establishing a mapping model of a color structure light field and grating parameters through pixel-level optical simulation; 2, determining a critical elongation threshold value of the mold in combination with finite element analysis, and constructing a grating parameter transformation algorithm to enable the hidden image to trigger explicit / implicit transformation under preset tensile strain; step 3, processing a precision grating mother set of the preorder design on the surface of the hard mold by adopting a micro / nano processing technology; and 4, a stretchable mold is formed through flexible material transfer printing, and grating parameters are dynamically changed by regulating and controlling tensile strain during mold pressing, so that a single-mold transfer printing multi-state optical structure is realized. Through dynamic parameter mapping and flexible mold deformation control, the problems of low multi-mold switching efficiency and high cost are solved, and a new path is provided for micro-nano structure manufacturing.

Description

Technical Field

[0001] This application belongs to the fields of optical design and precision glass molding processing, and particularly relates to a method for regulating grating parameters by tensile strain and reusing a single mold. Background Art

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

[0003] In the field of materials science, glass and polymers, as two important types of materials included in transparent media, 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, with its high transparency and high hardness, occupies an important position in fields such as doors, windows, and utensils. However, its surface processing is difficult, especially in terms of coloring and image style processing. Since glass is an inorganic non-metallic material with a stable chemical structure, it is difficult for conventional pigments to adhere evenly to its surface. Even if pigments are incorporated into the glass interior through complex processes such as high-temperature melting, it is often difficult to achieve an ideal color effect. Similarly, polymers are widely used in fields such as plastic packaging and coating materials due to their excellent flexibility and processing performance. However, their coloring process is often not satisfactory. Although their surface processing performance is relatively good, due to the long molecular chains of polymers, it is easy to form cross-linked network structures, making it difficult for pigment molecules to penetrate into their interior. Therefore, polymer coloring often requires special processes and pigments to ensure bright and lasting colors. At the same time, factors such as the surface tension and polarity of polymers also affect the coloring effect, making their coloring process relatively complex.

[0004] The molding equipment has significant advantages in the process of flexible template replication. It can achieve micron-level precision control, ensuring that the replicated graphics are highly consistent with the original design. Its high efficiency is another highlight. Compared with traditional manual replication, the molding equipment greatly shortens the replication cycle and improves production efficiency. In addition, the molding equipment is easy to operate and has strong stability. Operators with simple training can start operating, and it can maintain stable performance during replication, reducing production interruptions caused by equipment failures.

[0005] However, the molding equipment also has some disadvantages. The mold manufacturing is complex and costly, especially for molds with large and complex geometries. In addition, traditional molding usually can only achieve the replication of a single pattern and is difficult to meet the requirements of multi-pattern or dynamic patterns. To solve these problems, we propose a method for regulating grating parameters by tensile strain and reusing a single mold. This technology can switch multiple patterns on a single mold, trigger the appearance or hiding of patterns through stretching operations, and significantly improve the reusability and flexibility of the mold. Summary of the Invention

[0006] To solve the above problems, the purpose of this application is to provide a method for regulating grating parameters by tensile strain and reusing a single mold. By adjusting the cutting parameters, two or more micro-nano grating structures are embedded in a single mold, so that the mold can present different images in the relaxed and stretched states. Further, the device copies these images onto the surface of a transparent dielectric material such as glass or polymer through molding technology, realizing the efficient manufacturing of the reuse of multiple optical effects embedded in the surface of a single mold. This not only reduces the number of molds and lowers the production cost, but also provides new ideas and methods for the manufacturing of complex micro / nano structures on the surface of transparent dielectric materials.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A method for regulating grating parameters by tensile strain and reusing a single mold, comprising the following steps:

[0009] Step 1: Based on the multi-image display requirement, establish a mapping model between the color structured light field and the grating parameters 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 display / hiding conversion of the hidden image under a preset tensile strain;

[0011] Step 3: Use micro / nano processing technology to process the precision grating master plate designed in the previous step on the surface of the hard mold;

[0012] Step 4: Form a stretchable mold through flexible material transfer. During molding, regulate the tensile strain to dynamically change the grating parameters, and realize the transfer of multiple optical structures with a single mold.

[0013] Preferably, in step 1, the simulation and calculation of the raster structure parameters of the color image include:

[0014] Step 101: First, select two or more images to be embedded and process these images into appropriate sizes to control the number of processing pixels. This process is achieved through an image preprocessing algorithm, aiming to reduce the computational complexity while retaining the key color and structural information of the image. Subsequently, the pixel color information of the image is extracted through code calculation, including the Hue value or RGB color value. These color information are the basis for the subsequent raster structure design and are used to determine the structured light raster structure corresponding to each pixel color.

[0015] Step 102: According to the extracted pixel color information, convert it into the corresponding structured light wavelength. This conversion is based on optical principles and maps the color information of the image to the physical parameters of the raster structure. Specifically, the color information is combined with the diffraction characteristics of the raster through an optical model to determine the raster wavelength required for each pixel. The conversion formula is:

[0016] ;

[0017] where represents the raster wavelength, is a conversion function based on the optical model that maps color information (Hue or RGB) to the corresponding raster wavelength;

[0018] Step 103: Based on the grating diffraction equation, calculate the grating constant, grating depth, and grating period corresponding to each pixel through an 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: To ensure that the color image can be correctly displayed, simulate the grating diffraction process within the color pixel and calculate the light intensity:

[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 the auxiliary working surface respectively, , respectively represent the phase difference of single-grating double-working-surface interference and the phase difference of multi-grating interference, 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.

[0024] Step 105: Use the CIE 1931 color matching function to convert the spectral intensity within the visible spectral range into XYZ tristimulus coordinates, and further optimize the grating parameters to match the target color:

[0025] ;

[0026] ;

[0027] ;

[0028] ;

[0029] ;

[0030] where , , is the calibration color function of a 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 can be further optimized to match the target color, ensuring 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 be used as the basis for subsequent micro / nano structure processing to ensure 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 grating parameters for the image in the initial hidden state includes:

[0033] Step 201: Subdivide the machining area size, clarify the pixel sizes of the displayed and hidden images in the initial state, and perform a 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 pitch corresponding to its 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 achieve the display of the predetermined image in the unstretched state;

[0035] For an image hidden in the initial state, according to the mechanism of uniform deformation of the medium, the initial spacing of the grating structure corresponding to its pixels needs to be transformed and adjusted. The grating spacing used in micro-nano processing is

[0036] ;

[0037] where is the grating spacing after transformation and adjustment, is the calculated grating spacing, is the trigger image stretching rate.

[0038] Through this adjustment, it is ensured that in the unstretched state, the structured light generated by the grating structure is not within the visible light window range, and another predetermined image can be completely hidden; when the stretching rate reaches the trigger threshold the grating parameters after stretching and deformation exactly diffract to form colored visible light, achieving the effect of triggering the hidden picture. For the image that is not stretched and displayed, the grating parameters do not meet the visible light diffraction window at this time, thus achieving the hidden effect.

[0039] At the same time, by precisely controlling the processing parameters, the above-mentioned design of the grating spacing is realized, and the alternating process of image hiding and appearance is realized during the stretching process, and different trigger stretching rates can be set for multiple images to realize the animation process of alternating appearance and hiding of multiple images.

[0040] Step 202: Based on the elongation rate of the stretching trigger point, simulate the morphological changes of the grating structure in the stretched state according to the simulation process in Step 1, and adjust the grating constant to ensure the realization of the display / hiding conversion of the image during the stretching process. Through simulation analysis, determine the deformation law of the grating during the stretching process, and optimize the grating parameters to achieve the predetermined optical effect.

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

[0042] Step 204: Integrate the optimized grating parameters into a complete grating structure design drawing for subsequent micro / nano processing to ensure that the mold can realize the display / hiding state conversion of the image during the stretching process.

[0043] Preferably, in Step 3, the method of processing the grating structure on the surface of the hard mold by using micro / nano processing technology includes:

[0044] Step 301: Select a metal material or a hard non-metallic material as the mold substrate, and perform precision machining on the mold to form a micro-nano grating with a predetermined image and size.

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

[0046] Step 303: During the processing, it is necessary to strictly control the processing accuracy and surface roughness 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 to ensure the quality of the mold.

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

[0048] Preferably, in step 4, the method of replicating the grating structure on the mold using a flexible material includes:

[0049] Step 411: Select a flexible polymer material with a tensile rate matching the preset trigger tensile rate;

[0050] Step 412: Clean the mold surface;

[0051] Step 413: Coat the prepolymer on 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 a micro-nano grating structure.

[0055] Preferably, in step 4, the method of replicating the grating structure on the mold by hot embossing includes:

[0056] Step 421: Adopt hot embossing, cold embossing or ultraviolet curing embossing technology;

[0057] Step 422: Control the embossing 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: Press the substrate using a molding press under appropriate temperature and pressure conditions;

[0060] Step 452: Slowly release the pressure of the molding press and gradually cool the substrate;

[0061] Step 462: Take out the replicated transparent dielectric substrate from the flexible mold, check the quality of the replicated image, and at the same time, evaluate the replicated image using an optical microscope or other imaging devices;

[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 invention are:

[0064] (1) Through the method provided by the embodiments of the present invention, by using precise theoretical calculations and simulation simulations, the multiplexed and efficient manufacturing of multiple optical effects embedded in a single mold surface is achieved, enabling the mold to maintain a stable image display effect and excellent optical performance during long-term use.

[0065] (2) In the embodiments, through the application of micro / nano processing technologies and flexible materials, the mold can reversibly switch the image style during the stretching and relaxation processes, achieving different image display effects such as dynamic transformation and three-dimensional effects.

[0066] (3) The mold manufacturing method of the present invention is simple, has a low cost, can be mass-produced, is applicable to the manufacturing of various optical devices, and greatly broadens the application field of optical molds. Description of the Drawings

[0067] Figure 1 Shows a method flowchart of a method for regulating grating parameters by tensile strain and reusing a single mold provided by an embodiment of the present application;

[0068] Figure 2 Shows a schematic diagram of the surface grating topography and color distribution provided by an embodiment of the present application;

[0069] Figure 3 Shows a schematic diagram of two images presented before and after stretching by flexographic printing using a flexible template provided by an embodiment of the present application;

[0070] Figure 4 Shows a schematic diagram of the change in the surface grating during the stretching process of a flexible template provided by an embodiment of the present application;

[0071] Figure 5 Shows a schematic diagram of the images before and after stretching of a transparent dielectric by molding and copying provided by an embodiment of the present application. Detailed Embodiments

[0072] To make the objectives, technical solutions, and advantages of this technical solution clearer, the following further elaborates on this technical solution in conjunction with specific implementation manners. It should be understood that these descriptions are exemplary and do not limit the scope of this technical solution.

[0073] Example 1

[0074] Please refer to Figure 1 , Figure 1 The figure shows a flowchart of a process method provided by an embodiment of the present application for embedding two or more micro / nano structure morphologies on the surface of a single flexible mold, and realizing different optical effects on the molded surface through a stretching trigger and a glass molding process. The method includes:

[0075] S101. Based on the multi-image display requirements, establish a mapping model between the color structured light field and the grating parameters through pixel-level optical simulation.

[0076] S102. Combine finite element analysis to determine the critical elongation rate threshold of the mold, and construct a grating parameter transformation algorithm to enable the hidden image to trigger the display / hidden conversion under a preset tensile strain.

[0077] S103. Use micro / nano processing technology to machine the precision grating master plate designed in the previous step on the surface of the hard mold.

[0078] S104. Form a stretchable mold through flexible material transfer. During molding, adjust the tensile strain to dynamically change the grating parameters, and realize the transfer of multiple-state optical structures with a single mold.

[0079] Example 2. 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 an appropriate size to control the number of processing pixels. This process is realized through an image preprocessing algorithm, aiming to reduce the computational complexity while retaining the key color and structural information of the image. Subsequently, extract the pixel color information of the image through code calculation, including the Hue value or RGB color value. These color information are the basis for the subsequent grating structure design and are used to determine the structured light grating structure corresponding to each pixel color.

[0081] Step 202. According to the extracted pixel color information, convert it into the corresponding structured light wavelength. This conversion is based on optical principles and maps the color information of the image to the physical parameters of the grating structure. Specifically, combine the color information with the diffraction characteristics of the grating through an optical model to determine the grating wavelength required for each pixel. The conversion formula is:

[0082] ; (1)

[0083] Among them, represents the grating wavelength, represents 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 an optical diffraction model. The distance between two adjacent gratings in the machining direction is given by the following formula:

[0085] ; (2)

[0086] In the formula, and represent the incident angle and the 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 machining surface are functions of the machining tool geometry and process parameters:

[0088] ; (3)

[0089] In the formula, is the cutting speed, is the vibration frequency.

[0090] Step 205: To ensure the correct display of the color image, simulate the grating diffraction process within the color pixel and calculate the light intensity:

[0091] ; (4)

[0092] Among them is the light intensity of the incident light on the grating surface, is the spectral power reflectivity of the smooth mirror-like 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-working-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. Through this formula, the diffraction 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.

[0093] Step 206: Using the CIE 1931 color matching function, convert the spectral intensity within the visible spectral range into XYZ trichromatic coordinates, and 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 trichromatic coordinates, and the grating parameters can be 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 a grating structure design drawing, which will be used as the basis for subsequent micro / nano processing to ensure that the grating structure on the mold surface can precisely achieve the predetermined optical effect.

[0101] Through the method of Example 2, the whole process from extracting the pixel color information of the color image to optimizing the grating parameters is described in detail. This process includes calculating the structural light wavelength, determining the grating pitch, simulating the grating diffraction light intensity, and optimizing the grating parameters using the CIE1931 color matching function, and finally generating a grating structure design drawing to provide precise guidance for micro / nano processing.

[0102] Example 3: For an image in an initial hidden state, the method for integrating and calculating the grating parameters includes:

[0103] Step 301: Subdivide the size of the processing area, clarify the pixel sizes of the displayed and hidden images in the initial state, and perform a cross-arrangement design of the pixel positions. When designing the grating structure, the grating is divided into two parts:

[0104] For the image displayed in the initial state, the grating pitch corresponding to its pixels is directly processed according to the above calculation method, and the generated structural light is precisely controlled within the visible light wavelength range to achieve the predetermined image in the unstretched state;

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

[0106] ; (10)

[0107] wherein is the grating pitch after transformation and adjustment, is the calculated grating pitch, is the trigger image stretching rate.

[0108] Through this adjustment, it is ensured that in the non-stretched state, the structured light generated by the grating structure is not within the visible light window range, and another predetermined image can be completely hidden; when the stretching rate reaches the trigger threshold the grating parameters after stretching and deformation exactly diffract to form colored visible light, achieving the effect of triggering the hidden picture, while for the non-stretched displayed image, the grating parameters at this time do not meet the visible light diffraction window, thus achieving the hidden effect.

[0109] Meanwhile, by precisely controlling the processing parameters, the above design of the grating pitch is realized, and the process of alternating hiding and showing of the image is achieved during the stretching process, and different trigger stretching rates can be set for multiple images , realizing the animation process of alternating appearance and hiding of multiple images. The surface grating morphology and color change refer to Figure 2 .

[0110] Step 302: Based on the elongation rate of the stretching trigger point, simulate the morphological changes of the grating structure in the stretched state according to the simulation process in Step 1, and adjust the grating constant to ensure the realization of the display / hiding conversion of the image during the stretching process. Through simulation analysis, determine the deformation law of the grating during the stretching process, and optimize the grating parameters to achieve the predetermined optical effect.

[0111] Step 303: Perform simulation verification on the adjusted grating parameters according to the simulation steps of Embodiment 2 to ensure that the grating structure can accurately achieve the predetermined optical effect before and after stretching. The simulation verification includes the analysis of the grating diffraction efficiency, light intensity distribution, and color matching to ensure that the image can be correctly displayed during the stretching process.

[0112] Step 304: Integrate the optimized grating parameters into a complete grating structure design drawing for subsequent micro / nano processing to ensure that the mold can realize the display / hiding state conversion of the image during the stretching process.

[0113] Embodiment 3 proposes a method for integrating and calculating grating parameters for an initially hidden state image. By subdividing the processing area, designing an intersecting grating structure, and adjusting the grating parameters based on the stretching trigger point and the medium deformation mechanism, a complete grating structure design drawing is finally generated to ensure that the mold realizes the display / hiding state conversion of the image during the stretching process.

[0114] Example 4. The method for processing a color image on the surface of a hard mold using micro / nano processing technology includes:

[0115] Step 401. Select a metal material or a hard non-metal material as the mold substrate, and perform precision machining on 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 mold surface.

[0117] Step 403. During the processing, it is necessary to strictly control the processing accuracy and surface roughness to ensure the structural integrity and optical performance of the micro / nano grating. After processing, clean and inspect the mold to remove surface impurities and defects to ensure the quality of the mold.

[0118] Step 404. By adjusting the spacing and arrangement of the grating structure, different image display effects can be achieved, such as dynamic transformation, three-dimensional effect, etc. 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 Example 4, a method for processing a micro / nano grating structure with two embedded image styles on the surface of a metal mold was successfully developed, and the appearance and hiding of the image were correctly controlled, thus realizing the change of the color image, providing a key mold technology basis for the subsequent precise coloring process on transparent dielectric materials.

[0120] Example 5. The method for using a flexible material to replicate the grating structure on the mold includes:

[0121] Step 501. The flexible material is a polymer material with specific elongation and optical properties to achieve reversible switching of the image style during the stretching and relaxation processes.

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

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

[0124] Step 503. Coat the prepolymer on the surface of the micro / nano grating structure of the metal mold.

[0125] In this step, it is necessary to precisely control the thickness of the coating layer, which can be achieved by using a coating knife, screen printing, or spin coating methods.

[0126] Meanwhile, during the coating process, it is necessary to ensure that the prepolymer uniformly covers the surface of the mold to avoid the generation of bubbles and defects.

[0127] Step 504: Under room temperature or slightly heated conditions, fully cure the prepolymer to ensure the complete replication of the structure.

[0128] In this step, the curing process usually involves leaving it at room temperature for several hours or accelerating the curing in 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 the micro-nano grating structure from the metal mold.

[0130] Step 506: Inspect the replicated flexible material surface layer to confirm the integrity and accuracy of the micro-nano grating structure.

[0131] In this step, it can be carried out through an optical microscope, a scanning electron microscope (SEM), or other surface analysis techniques.

[0132] Step 507: Conduct performance tests on 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 disappearance of the image during the stretching process.

[0134] In this step, during the stretching process, the grating spacing of the unstretched image gradually increases. According to the grating equation formula (2), the spacing is proportional to the wavelength, and as the wavelength gradually increases, the image gradually disappears, as Figure 3 shown.

[0135] Meanwhile, the change of the grating on the surface of the flexible material during the stretching process is as Figure 4 shown.

[0136] Through the method of Example 5, the micro-nano grating structure on the metal mold is transferred to the prepolymer surface layer by using the replication technology, and the precise replication of the micro-nano structure is successfully achieved. This replication technology not only has high repeatability and stability, but also can retain the microscopic structure and features of the metal surface, providing a high-quality template for the subsequent replication of the molding equipment.

[0137] Example 6: The method for replicating the grating structure on the mold by molding includes:

[0138] Step 601: The molding technology includes hot embossing, cold embossing, ultraviolet curing embossing, etc.;

[0139] Step 602: Prepare a transparent dielectric substrate and select an appropriate size and shape to adapt to the molding process.

[0140] In this step, the surface of the substrate should be smooth, clean, without scratches or defects to ensure the quality of image replication.

[0141] Step 603: If the picture displayed in the original state is to be replicated, directly place the transparent medium substrate on the flexible mold; if the hidden picture is to be replicated, stretch the flexible mold until the stretching rate is triggered 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 press to apply pressure to 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 replicated on the transparent medium surface.

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

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

[0145] Meanwhile, use an optical microscope or other imaging equipment to evaluate the replicated image to ensure color accuracy and image clarity.

[0146] Here, the process of molding and replicating the two images before and after stretching on the transparent medium with the flexible one as the template is as Figure 5 shown.

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

[0148] Step 608: Conduct performance tests on the final product, including color stability, scratch resistance, weather resistance, etc., to ensure its reliability in the expected application environment.

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

[0150] The above content is only the preferred embodiment of the present invention. For those of ordinary skill in the art, many changes can be made in the specific implementation manners and application scopes according to the idea of the present technical content. As long as these changes do not depart from the concept of the present invention, they all fall within the protection scope of this patent.

Claims

1. A method for regulating grating parameters by tensile strain and reusing a single mold, characterized in that: The method includes the following steps: Step 1: Based on the multi-image display requirement, establish a mapping model between the color structured light field and the grating parameters through pixel-level optical simulation; Step 2: Combine finite element analysis to determine the critical elongation rate threshold of the mold, and construct a grating parameter transformation algorithm to trigger the display / hide conversion of the hidden image under a preset tensile strain; Step 3: Use micro / nano processing technology to machine the precision grating master plate designed in the previous step on the surface of the hard mold; Step 4: Form a stretchable mold through flexible material transfer. During molding, control the tensile strain to dynamically change the grating parameters, and realize the transfer of multi-state optical structures with a single mold.

2. A method for regulating grating parameters by tensile strain and reusing a single mold according to claim 1, characterized in that: 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 control the number of processed pixels, and extract the pixel color information of the image. The pixel color information includes hue values or RGB color values; Step 102: According to the pixel color information, map the color information to the corresponding grating wavelength through an optical model. The conversion formula is: ； Among them, 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, calculate the grating constant corresponding to each pixel through an optical diffraction model; ； In the formula, 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 within the color pixel and calculate the light intensity; ； Among them is the light intensity of the incident light on the grating surface, is the spectral power reflectivity of the smooth mirror metal surface, and respectively represent the combined vibration parameters of the main working surface and the auxiliary working surface, and respectively represent the phase difference of the single grating double working surface interference and the phase difference of the multi-grating interference, is the number of surface gratings, is the amplitude spectrum of the incident light wave; Step 105: Use the CIE 1931 color matching function to convert the spectral intensity within the visible light spectrum into XYZ trichromatic coordinates; ； ； ； ； ； wherein , , are the calibration color functions of the 2° standard observer, and are the upper and lower limits of the visible spectrum, represents the spectral intensity; Step 106: Integrate the calculated grating parameters into a grating structure design drawing.

3. A method for regulating grating parameters by tensile strain and reusing a single mold according to claim 2, 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 size of the processing area, clarify the pixel sizes of the displayed and hidden images in the initial state, and perform a cross-arrangement design of pixel positions; calculate the grating pitch corresponding to the pixels of the displayed image according to the method described in claim 2; adjust the grating pitch corresponding to the pixels of the hidden image according to the mechanism of uniform deformation of the medium; ； Among them is the grating pitch after transformation and adjustment, is the calculated grating pitch, is the trigger image stretch ratio; Step 202: Based on the preset stretching rate, simulate the morphological changes of the grating structure in the stretched state according to the simulation process in step 1 of claim 1, and adjust the grating constant; Step 203: Perform simulation verification on the adjusted grating parameters. The simulation verification includes the 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 drawing.

4. A method for regulating grating parameters by tensile strain and reusing a single mold according to claim 3, characterized in that: In step 3, the method for machining a grating structure on the surface of a hard mold using micro / nano processing technology includes: Step 301: Select a metal material or a hard non-metal material as the mold substrate, and perform precision machining on the mold; Step 302: According to the design requirements of the grating structure, select vibration cutting, femtosecond laser direct writing, or electron beam lithography micro / nano processing technology to machine a micro / nano grating structure on the surface of the mold; Step 303: During the processing, control the processing precision and surface roughness; Step 304: Adjust the spacing and arrangement of the grating structure according to the grating structure design drawing.

5. A method for regulating grating parameters by tensile strain and reusing a single mold according to claim 1, wherein: In step 4, the method of replicating the grating structure on the mold using a flexible material includes: Step 411: Select a flexible polymer material with a tensile rate matching the preset trigger tensile rate; Step 412: Clean the surface of the mold; Step 413: Coat the surface of the micro-nano grating structure of the hard mold with a prepolymer; Step 414: Control the thickness of the coating layer; Step 415: Cure the prepolymer at room temperature or under slightly heated conditions; Step 416: Peel off the cured flexible material layer to obtain a flexible mold with a micro-nano grating structure.

6. A method for regulating grating parameters by tensile strain and reusing a single mold according to claim 5, wherein: In step 4, the method of replicating the grating structure on the flexible mold by molding includes: Step 421: Adopt hot embossing, cold embossing or ultraviolet curing embossing technology; Step 422: Control the embossing temperature, pressure and time; 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 stretch ratio and then place the transparent medium substrate thereon. Step 442: Press the substrate using an embossing machine under appropriate temperature and pressure conditions; Step 452: Slowly release the pressure of the embossing machine and gradually cool the substrate; Step 462: Take out the replicated transparent medium substrate from the flexible mold, check the quality of the replicated image, and at the same time, evaluate the replicated image using an optical microscope or other imaging equipment; Step 472: If necessary, repeat steps 411 to 462 to verify the repeatability and reliability of the experimental results.

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