A photolithography method and system for holographic anti-counterfeiting printing

Abstract

The present application discloses a photolithography method and system for holographic anti-counterfeiting printing, which relates to the field of printing data processing. The method comprises: receiving at least one grayscale image, encoding preset holographic anti-counterfeiting information into the grayscale image to obtain a holographic anti-counterfeiting grayscale image, and determining the spatial frequency and pattern complexity of the holographic anti-counterfeiting grayscale image; determining the frequency of a laser according to the spatial frequency and the pattern complexity; determining the exposure angle range of the laser and the scanning path on a substrate according to the fine pattern of the holographic anti-counterfeiting grayscale image; receiving a first instruction, and acquiring the intensity of reflected light on the substrate and the clarity of an interference pattern on the substrate in real time according to the frequency and the exposure angle range of the laser; determining the optimal focal position of the optical system according to the intensity of the reflected light and the clarity of the interference pattern on the substrate; generating a second instruction according to the optimal focal position; performing photolithography on a fixed substrate by a laser to obtain a three-dimensional holographic anti-counterfeiting pattern.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of printing data processing, and in particular to a photolithography method and system for holographic anti-counterfeiting printing. Background Art

[0002] Holographic anti-counterfeiting printing is a method of using holographic technology to produce anti-counterfeiting marks. It generates three-dimensional images or specific optical effects by recording and reproducing the interference and diffraction patterns of light, making these marks difficult to copy. It is widely used in the fields of certificates, product packaging, etc.

[0003] Existing holographic anti-counterfeiting printing is achieved through a photolithography machine, which has built-in image processing software and photolithography software. The image processing software is used to process the input image to ensure that the image can be accurately reproduced on the photolithography machine. Its main function is to convert the input image into a grayscale image. The photolithography software is used to perform photolithography operations on the grayscale image processed by the image processing algorithm module. The main process of the photolithography operation is: aligning the substrate with the photolithography machine to ensure accurate positioning of the pattern; using a laser to scan and expose the grayscale image to generate a pattern; using a laser to perform photolithography on the substrate to obtain a three-dimensional holographic anti-counterfeiting pattern.

[0004] However, in the current lithography process, the grayscale image after the above image processing needs to be manually exported from the image processing software and imported into the lithography software, and some processes in the lithography software need to be manually controlled, such as aligning the substrate with the lithography machine, using a laser to scan and expose the grayscale image, etc. Since manual export and import of images increases the complexity of the process and steps such as manually aligning the substrate and manually controlling the laser for scanning and exposure increase the operation time, the above manual operation steps will greatly prolong the lithography time and reduce the overall production efficiency. For mass production, it will significantly delay the overall production time.

[0005] Therefore, there is an urgent need for a method to save manual operation time and improve overall production efficiency. Summary of the invention

[0006] The embodiments of the present application provide a lithography method and system for holographic anti-counterfeiting printing, which are used to save manual operation time, improve overall production efficiency, and minimize overall production time.

[0007] To achieve the above objectives, the embodiments of the present application adopt the following technical solutions:

[0008] In a first aspect, a lithography method for holographic anti-counterfeiting printing is provided, which is applied to a lithography machine, wherein the lithography machine includes a laser, an optical system, and a vacuum adsorption system. The method includes:

[0009] In response to receiving at least one grayscale image, obtaining a first grayscale value of the grayscale image;

[0010] Converting the preset holographic anti-counterfeiting information into a target grayscale image, and acquiring a second grayscale value of the target grayscale image;

[0011] Modulating the first grayscale value of the grayscale image by the second grayscale value of the target grayscale image to embed the second grayscale value into the grayscale image, thereby obtaining a holographic anti-counterfeiting grayscale image, wherein the grayscale value of the holographic anti-counterfeiting grayscale image is a third grayscale value;

[0012] Performing Fourier transformation on the holographic anti-counterfeiting grayscale image to obtain a frequency spectrum of the holographic anti-counterfeiting grayscale image;

[0013] Determine the frequency distribution of the holographic anti-counterfeiting grayscale image according to the frequency spectrum, and perform weighted averaging on the frequency distribution of the holographic anti-counterfeiting grayscale image to calculate the spatial frequency of the holographic anti-counterfeiting grayscale image;

[0014] determining the pattern complexity of the holographic anti-counterfeiting grayscale image according to the third grayscale value of the holographic anti-counterfeiting grayscale image;

[0015] determining the frequency of the laser according to the spatial frequency and the pattern complexity, wherein the holographic anti-counterfeiting grayscale image is composed of fine patterns;

[0016] Determining the exposure angle range of the laser and the scanning path of the laser on the substrate according to the fine pattern of the holographic anti-counterfeiting grayscale image;

[0017] In response to receiving a first instruction, according to the frequency of the laser and the exposure angle range, controlling the laser to scan the surface of the substrate according to the scanning path, so as to obtain in real time the intensity of the reflected light on the substrate and the clarity of the interference pattern on the substrate, wherein the first instruction is used to instruct the lithography machine to scan the surface of the substrate;

[0018] Determining the optimal focal length position of the optical system according to the intensity of the reflected light and the clarity of the interference pattern on the substrate;

[0019] generating a second instruction according to the optimal focal length position, wherein the second instruction is used to instruct the vacuum adsorption system to start so as to fix the substrate;

[0020] The laser is used to perform photolithography on the fixed substrate to obtain a three-dimensional holographic anti-counterfeiting pattern.

[0021] In a possible implementation manner of the first aspect, determining the pattern complexity of the holographic anti-counterfeiting grayscale image according to the third grayscale value of the holographic anti-counterfeiting grayscale image includes:

[0022] According to the third grayscale value, the entropy value and the density of edge pixels of the holographic anti-counterfeiting grayscale image are calculated, wherein the entropy value and the density of edge pixels of the holographic anti-counterfeiting grayscale image are used to characterize the pattern complexity of the holographic anti-counterfeiting grayscale image.

[0023] In another possible implementation manner of the first aspect, modulating the first grayscale value of the grayscale image by the second grayscale value of the target grayscale image to embed the second grayscale value into the grayscale image to obtain a holographic anti-counterfeiting grayscale image includes:

[0024] Normalizing the first grayscale value to obtain a normalized first grayscale value, and normalizing the second grayscale value to obtain a normalized second grayscale value;

[0025] Using multiplication modulation, the second grayscale value after normalization is modulated by the first grayscale value after normalization to obtain the third grayscale value;

[0026] Determine whether the grayscale value range of the third grayscale value exceeds the range of [0,1];

[0027] When the grayscale value range of the third grayscale value exceeds the range of [0, 1], clipping the grayscale value range of the third grayscale value so that the grayscale value range of the third grayscale value is within the range of [0, 1];

[0028] The holographic anti-counterfeiting grayscale image is synthesized according to the third grayscale values ​​of all pixels.

[0029] In another possible implementation manner of the first aspect, determining the frequency of the laser according to the spatial frequency and the pattern complexity includes:

[0030] Calculating the fundamental frequency of the laser according to the spatial frequency;

[0031] The basic frequency is corrected and calculated according to the entropy value of the holographic anti-counterfeiting grayscale image and the density of edge pixels to obtain the frequency of the laser.

[0032] In another possible implementation of the first aspect, determining the exposure angle range of the laser and the scanning path of the laser on the substrate according to the fine pattern of the holographic anti-counterfeiting grayscale image includes:

[0033] Determining the spatial frequency and directional information of the fine pattern through the spectrum of the holographic anti-counterfeiting grayscale image, wherein the spatial frequency of the fine pattern is consistent with the spatial frequency of the holographic anti-counterfeiting grayscale image, and the directional information includes the main frequency direction of the spectrum;

[0034] dividing the fine pattern into a high-frequency pattern and a low-frequency pattern according to the spatial frequency of the fine pattern;

[0035] determining an angular offset of the laser according to the spatial frequency and the pattern complexity;

[0036] Determining an initial exposure angle range of the laser according to the main frequency direction and the angle offset of the laser;

[0037] Correcting the initial exposure angle range according to the high-frequency pattern and the low-frequency pattern to obtain an exposure angle range of the laser;

[0038] Identify the type of the micro-pattern, and determine the scanning path of the laser on the substrate according to the type of the micro-pattern, wherein the type of the micro-pattern includes a linear pattern, an annular pattern and / or a spiral pattern, when the type of the micro-pattern is the linear pattern, the scanning path is a parallel linear scanning path, when the type of the micro-pattern is the annular pattern or the spiral pattern, the scanning path is a spiral scanning path, when the type of the micro-pattern is a combination of the linear pattern and the annular pattern, the scanning path is a parallel linear scanning path and the spiral scanning path, and when the type of the micro-pattern is a combination of the linear pattern and the spiral pattern, the scanning path is a parallel linear scanning path and the spiral scanning path.

[0039] In another possible implementation manner of the first aspect, after determining the exposure angle range of the laser and the scanning path of the laser on the substrate according to the fine pattern of the holographic anti-counterfeiting grayscale image, the method further includes:

[0040] An adaptive scanning strategy is adopted to adjust the density and speed of the scanning path according to the change of the spatial frequency of the fine pattern.

[0041] In another possible implementation manner of the first aspect, determining the optimal focal length position of the optical system according to the intensity of the reflected light and the clarity of the interference pattern on the substrate includes:

[0042] Starting from an initial focal length position of the optical system, gradually adjusting the focal length of the optical system according to a preset unit step length, and acquiring the intensity of the reflected light and the clarity of the interference pattern on the substrate at each focal length position;

[0043] At all focal length positions, comparing the intensity of the reflected light and the clarity of the interference pattern on the substrate at adjacent focal length positions, and determining the trend change of the intensity of the reflected light and the clarity of the interference pattern on the substrate;

[0044] An optimal focal length position is determined according to the trend change, wherein a gain of the trend change before and after the optimal focal length position is less than a preset threshold.

[0045] In another possible implementation manner of the first aspect, the vacuum adsorption system includes an adsorption pressure sensor, and generating the second instruction according to the optimal focal length position includes:

[0046] During the vacuum adsorption process of the vacuum adsorption system, the vacuum pressure of the vacuum adsorption system is obtained in real time through the adsorption pressure sensor;

[0047] Corresponding the optimal focal length position to each target area of ​​the substrate, and determining the focal length of each target area, wherein the substrate includes at least two target areas;

[0048] Determining the focal length change of adjacent target areas according to the focal length of each target area;

[0049] When the focal length variation is less than or equal to a preset variation, determining that the substrate is flat;

[0050] When the substrate is flat, a pressurization operation or a depressurization operation for each target area is determined according to the focal length of each target area, and a second instruction is generated according to the pressurization operation or the depressurization operation for each target area.

[0051] In a second aspect, the present application provides a lithography device for holographic anti-counterfeiting printing, comprising:

[0052] a memory configured to store instructions; and

[0053] The processor is configured to call the instructions from the memory and implement the above-mentioned lithography method for holographic anti-counterfeiting printing when executing the instructions.

[0054] In a third aspect, the present application provides a lithography machine, comprising:

[0055] The above-mentioned lithography device for holographic anti-counterfeiting printing;

[0056] Lasers;

[0057] Optical system;

[0058] Vacuum adsorption system.

[0059] In a fourth aspect, the present application provides a lithography system for holographic anti-counterfeiting printing, comprising:

[0060] The above-mentioned lithography machine.

[0061] Through the above technical solution, after receiving the grayscale image, the holographic anti-counterfeiting information is automatically encoded into the grayscale image, and the frequency and exposure angle range of the laser are automatically adjusted according to the spatial frequency and pattern complexity of the image. There is no need to manually export the grayscale image and import it into the lithography software, which reduces the complexity of the process and effectively saves operation time. At the same time, by obtaining the intensity of the reflected light on the substrate and the clarity of the interference pattern in real time, the optimal focal length position of the optical system is automatically determined, and the substrate is fixed according to the instructions generated according to the optimal focal length, ensuring the precise alignment of the substrate and reducing the time for manual adjustment. In addition, the scanning path of the laser is automatically determined according to the fine pattern of the holographic anti-counterfeiting grayscale image, which further reduces the need for manual operation, improves production efficiency, and solves the complexity and inefficiency caused by manual operation in the existing process.

[0062] Other features and advantages of the embodiments of the present application will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 A schematic diagram of a holographic anti-counterfeiting printing process provided in an embodiment of the present application;

[0064] Figure 2 A schematic diagram of a process flow of a photolithography method for holographic anti-counterfeiting printing provided in an embodiment of the present application;

[0065] Figure 3 A schematic diagram of the structure of an optical system provided in an embodiment of the present application;

[0066] Figure 4 A schematic diagram of the structure of a vacuum adsorption system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0067] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It should be understood that the specific implementation methods described herein are only used to illustrate and explain the embodiments of the present application, and are not used to limit the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0068] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back...), such directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0069] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present application, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0070] In order to facilitate the understanding of this solution, the lithography machine used for holographic anti-counterfeiting printing is first described as follows:

[0071] The hologram formed by the lithography machine used for holographic anti-counterfeiting printing can display different images or colors under different light and is used for anti-counterfeiting purposes.

[0072] Figure 1 A schematic diagram of a holographic anti-counterfeiting printing process provided by an embodiment of the present application is shown. Figure 1 As shown, the working process of the lithography machine used for holographic anti-counterfeiting printing is as follows: first, design a hologram, which usually contains a complex interference pattern; make a photomask containing the interference pattern, which usually contains micron or nanometer details; use a laser or ultraviolet light source to irradiate the photomask for exposure, and after the light source passes through the pattern on the photomask, an interference pattern is formed on the target substrate (such as plastic film or paper), and the interference pattern transfers the hologram to the target substrate, which is usually pre-coated with a layer of photosensitive material (such as photoresist); the photosensitive material forms the desired holographic pattern on the target substrate; the target substrate is developed to obtain a holographic pattern, and the holographic pattern is solidified by physical or chemical methods.

[0073] According to the above holographic anti-counterfeiting printing process, Figure 2 The schematic diagram of the process of a lithography method for holographic anti-counterfeiting printing according to an embodiment of the present application is shown. Figure 2 As shown, an embodiment of the present application provides a lithography method for holographic anti-counterfeiting printing, which is applied to a lithography machine. The lithography machine includes a laser, an optical system and a vacuum adsorption system. The method may include the following steps.

[0074] S110, in response to receiving at least one grayscale image, encoding preset holographic anti-counterfeiting information into the grayscale image to obtain a holographic anti-counterfeiting grayscale image, and determining a spatial frequency and pattern complexity of the holographic anti-counterfeiting grayscale image;

[0075] S120, determining the frequency of the laser according to the spatial frequency and the pattern complexity, wherein the holographic anti-counterfeiting grayscale image is composed of fine patterns;

[0076] S130, determining the exposure angle range of the laser and the scanning path of the laser on the substrate according to the fine pattern of the holographic anti-counterfeiting grayscale image;

[0077] S140, in response to receiving the first instruction, controlling the laser to scan the surface of the substrate according to the scanning path according to the frequency and exposure angle range of the laser, so as to obtain the intensity of the reflected light on the substrate and the clarity of the interference pattern on the substrate in real time, wherein the first instruction is used to instruct the lithography machine to scan the surface of the substrate;

[0078] S150, determining the optimal focal length position of the optical system according to the intensity of the reflected light and the clarity of the interference pattern on the substrate;

[0079] S160, generating a second instruction according to the optimal focal length position, the second instruction being used to instruct the vacuum adsorption system to start to fix the substrate;

[0080] S170, performing photolithography on the fixed substrate by means of a laser to obtain a three-dimensional holographic anti-counterfeiting pattern.

[0081] In this embodiment, the preset holographic anti-counterfeiting information is encoded into the grayscale image to obtain the holographic anti-counterfeiting grayscale image, and the spatial frequency and pattern complexity of the holographic anti-counterfeiting grayscale image are determined, including:

[0082] S111, obtaining a first grayscale value of the grayscale image;

[0083] S112, converting the preset holographic anti-counterfeiting information into a target grayscale image, and obtaining a second grayscale value of the target grayscale image;

[0084] S113, modulating the first grayscale value of the grayscale image by the second grayscale value of the target grayscale image to embed the second grayscale value into the grayscale image, thereby obtaining a holographic anti-counterfeiting grayscale image, wherein the grayscale value of the holographic anti-counterfeiting grayscale image is a third grayscale value;

[0085] S114, performing Fourier transform on the holographic anti-counterfeiting grayscale image to obtain a frequency spectrum of the holographic anti-counterfeiting grayscale image;

[0086] S115, determining the frequency distribution of the holographic anti-counterfeiting grayscale image according to the spectrum diagram, and performing weighted averaging on the frequency distribution of the holographic anti-counterfeiting grayscale image to calculate the spatial frequency of the holographic anti-counterfeiting grayscale image;

[0087] S116. Determine the pattern complexity of the holographic anti-counterfeiting grayscale image according to the third grayscale value of the holographic anti-counterfeiting grayscale image.

[0088] Grayscale images are images that use different grayscale levels to represent brightness. The preset holographic anti-counterfeiting information can be a specific pattern, logo or text, which can be converted into corresponding grayscale levels and encoded into the grayscale image to achieve anti-counterfeiting function.

[0089] The spatial frequency of a holographic anti-counterfeiting grayscale image refers to the frequency of brightness changes in the holographic anti-counterfeiting grayscale image, usually expressed as the number of light and dark alternations per unit length. A high spatial frequency means more details and rapid brightness changes in the image. Pattern complexity refers to the details and degree of variation of the pattern. The higher the pattern complexity, the more details and variations in the pattern need to be accurately reproduced.

[0090] Specifically, S116 includes:

[0091] S210. Calculate the entropy value of the holographic anti-counterfeiting grayscale image and the density of edge pixels according to the third grayscale value, wherein the entropy value of the holographic anti-counterfeiting grayscale image and the density of edge pixels are used to characterize the pattern complexity of the holographic anti-counterfeiting grayscale image.

[0092] In one of the embodiments, encoding the holographic anti-counterfeiting information into the grayscale image can be achieved using a modulation method. Specifically, the holographic anti-counterfeiting information is first determined. The holographic anti-counterfeiting information can be a specific logo, pattern, text or other anti-counterfeiting feature. For example, a set of binary-coded data can be selected, such as a QR code, a specific logo or a text pattern. Secondly, the selected holographic anti-counterfeiting information is converted into a grayscale image, that is, the anti-counterfeiting information is converted from binary or other formats to a form suitable for grayscale images. For example, if it is binary information, a grayscale image can be generated by mapping "1" to a higher grayscale value (such as 255) and mapping "0" to a lower grayscale value (such as 0). Then, the grayscale value of the holographic anti-counterfeiting information can be used to modulate the grayscale value of the original grayscale image to achieve encoding of the preset holographic anti-counterfeiting information into the grayscale image.

[0093] In another embodiment, in addition to using the modulation method, a superposition method can be used to superimpose the holographic anti-counterfeiting grayscale image on the grayscale image, and the transparency of the superposition can be adjusted according to the grayscale value.

[0094] In the specific implementation, it is necessary to process the image details to prevent excessive impact on the original grayscale image. A low-pass filter or Gaussian blur can be applied to smooth the fused holographic anti-counterfeiting grayscale image to ensure that the holographic anti-counterfeiting information is naturally integrated with the original grayscale image.

[0095] The spatial frequency and pattern complexity of the holographic anti-counterfeiting grayscale image can be obtained through the spectrum of the holographic anti-counterfeiting grayscale image. Specifically, the holographic anti-counterfeiting grayscale image is first subjected to Fourier transform to convert the holographic anti-counterfeiting grayscale image from the spatial domain to the frequency domain. The Fourier transform can be expressed by the following formula:

[0096] ;

[0097] in, is the value of the grayscale image in the spatial domain, is the value in the frequency domain.

[0098] Secondly, the main frequency of the image can be determined through the spectrum after Fourier transformation. The main frequency refers to the frequency point with the largest amplitude (intensity) in the spectrum after Fourier transformation, which means the frequency point corresponding to the spatial frequency that appears most in the image. The intensity of the main frequency refers to the amplitude of the spectrum at this frequency point, which represents the energy or contribution of the frequency component in the image. The average spatial frequency represents the average frequency of all frequency components in the image, which is the result of weighted averaging of the frequency distribution in the entire spectrum. The higher the spatial frequency, the more details the image has. The formula is as follows:

[0099] ;

[0100] in is the amplitude of each point in the frequency domain, Indicates frequency.

[0101] The pattern complexity can be determined by calculating the entropy of the holographic anti-counterfeiting grayscale image and the density of edge pixels. It can be expressed as:

[0102] ;

[0103] in, is the number of gray levels, Is grayscale The higher the entropy value, the higher the pattern complexity.

[0104] Edge pixel density can be achieved by performing edge detection (such as Sobel operator) on the image and calculating the density of edge pixels. The higher the edge density, the higher the pattern complexity.

[0105] By converting the holographic anti-counterfeiting information into a target grayscale image and modulating it into the original grayscale image, the generated holographic anti-counterfeiting grayscale image can contain the preset anti-counterfeiting information, ensuring a high degree of integration of the anti-counterfeiting information and the image, and increasing the concealment and difficulty of replicability of the anti-counterfeiting information. At the same time, the spectrum diagram obtained by Fourier transform and the calculated spatial frequency can effectively analyze the frequency distribution characteristics of the holographic anti-counterfeiting grayscale image. The pattern complexity is determined by calculating the entropy value of the grayscale image and the density of edge pixels, which is conducive to ensuring the accuracy of subsequent laser frequency determination.

[0106] The frequency of the laser determines the rate of the laser pulse, which refers to the number of laser pulses emitted per second. When processing images with high spatial frequencies, a higher laser frequency is required to ensure that the fine patterns are accurately etched on the substrate by the laser pulses. For complex patterns, the frequency of the laser needs to be adjusted to adapt to the changes in the pattern. For example, when processing complex patterns, a higher laser frequency can better process parts with rich details, ensuring that the laser can cover all changing areas, thereby obtaining a high-precision holographic pattern. Therefore, the frequency of the laser can be determined based on the spatial frequency and pattern complexity.

[0107] In the lithography method of holographic anti-counterfeiting printing, after receiving at least one grayscale image, the preset holographic anti-counterfeiting information is encoded into the grayscale image to generate a holographic anti-counterfeiting grayscale image. The holographic anti-counterfeiting information (such as text, logo or pattern) can be converted into grayscale values ​​using an image processing algorithm. Each pixel in the grayscale image represents a different brightness, and the brightness value encodes the holographic anti-counterfeiting information. By using methods such as Fourier transform, the spatial frequency and pattern complexity of the holographic anti-counterfeiting grayscale image can be analyzed and determined. After determining the spatial frequency and pattern complexity, the lithography accuracy required for the holographic anti-counterfeiting grayscale image can be determined, and then the frequency of the laser can be determined.

[0108] Next, the frequency of the laser can be determined based on the spatial frequency and pattern complexity. The frequency of the laser determines the emission rate of the laser pulses during the lithography process. Assuming the spatial frequency is 100 lines per millimeter and the pattern complexity is high, it means that the laser needs to accurately etch 100 subtle light and dark changes within each millimeter, and a higher laser frequency is required to achieve this accuracy. If a laser with a frequency of 10kHz is selected, it can emit 10,000 pulses per second, which can form a highly complex holographic anti-counterfeiting pattern on the substrate.

[0109] After determining the frequency of the laser, the exposure angle range and scanning path of the laser can be determined according to the fine pattern of the holographic anti-counterfeiting grayscale image. Specifically, the fine pattern refers to a small and fine pattern in the grayscale image. In a specific implementation, the grayscale image can be first analyzed, and the optimal laser exposure angle range and scanning path can be determined based on the analysis results. The exposure angle range can ensure that the laser beam can cover all areas on the substrate, while the scanning path can determine the trajectory of the laser moving on the surface of the substrate. The above process can be simulated by computer-aided design (such as CAD) software to ensure the accuracy of the path. For example, if the pattern on the substrate is a spiral pattern, the scanning path should closely follow the spiral curve of the spiral pattern to maximize the clarity and accuracy of the pattern.

[0110] After the exposure angle range of the laser and the scanning path of the laser on the substrate are set, the lithography machine receives a first instruction to control the laser to scan the substrate surface according to the set scanning path based on the frequency and exposure angle range of the laser.

[0111] Specifically, in the process of scanning the substrate, the intensity of the reflected light on the substrate and the clarity of the interference pattern are obtained in real time. The intensity of the laser reflected from the substrate surface and the resulting interference pattern can be detected by a photoelectric sensor. The clarity of the interference pattern reflects the accuracy of laser etching.

[0112] The optimal focal position of the optical system can be determined based on the detected reflected light intensity and the clarity of the interference pattern. Since the focal position of the optical system directly affects the focusing quality of the laser beam on the substrate surface, by adjusting the focal length of the optical system, it can be ensured that the laser beam always remains in the optimal focusing state during the etching process, thereby generating a clear pattern on the substrate.

[0113] In this embodiment, in order to determine the optimal focal length position, the feedback data of the reflected light and the interference pattern can be used for continuous adjustment until the most suitable focal length is found. For example, if the interference pattern is blurred, the optical system will gradually adjust the focal length until the interference fringes are clear. The above process is completed by an automatic focusing device, which can accurately control the tiny increments of focal length change.

[0114] The optical system is used to achieve precise focusing and scanning of the laser, Figure 3 A schematic diagram of the structure of an optical system provided in an embodiment of the present application is shown. Figure 3 As shown, the optical system includes a laser beam shaper, a focusing lens, an adjustable mirror, a beam splitter, filters and wave plates, an autofocus system, and an optical path protection system.

[0115] Laser beam shapers are used to adjust the shape of the beam emitted by the laser to the desired shape and size. For example, a divergent laser beam is focused into a parallel beam or a spot of a specific shape so that the laser action area on the substrate can be more accurately controlled. Shapers are usually composed of lenses, prisms or special optical elements, which shape the beam by changing the optical path.

[0116] The focusing lens is used to focus the shaped laser beam onto the surface of the substrate. The focal length of the focusing lens determines the focal size and position of the beam on the substrate, which directly affects the fineness of the photolithography. A short focal length lens can focus the laser beam to a very small spot, thereby achieving high-precision etching.

[0117] Adjustable mirrors are used to change the direction of the laser beam, usually by slightly adjusting the angle to achieve scanning of the laser beam. In order to achieve high-precision control, the mirror can be mounted on a precision electric or piezoelectric drive and the angle can be adjusted by computer instructions.

[0118] Beam splitters are used to split a single laser beam into multiple beams, enabling simultaneous lithography of multiple areas of a substrate. The working principle of a beam splitter is to partially reflect and partially transmit the laser beam using a half-mirror or prism to improve lithography efficiency, especially when processing large-area substrates.

[0119] Filters are used to select lasers of specific wavelengths and to reduce the interference of stray light by filtering out unwanted parts of the spectrum. Wave plates (such as λ / 2 or λ / 4 wave plates) are used to adjust the polarization state of lasers.

[0120] The autofocus system can automatically adjust the position of the focusing lens by monitoring the intensity of the reflected light or the clarity of the interference pattern in real time. The autofocus system ensures that the laser beam is always focused on the optimal position of the substrate to achieve high-quality lithography. Specifically, the autofocus system uses a motor drive or piezoelectric element to precisely control the lens position and combines it with a feedback loop to achieve automatic adjustment.

[0121] The optical path protection system includes a housing and air filtration device for protecting and cleaning optical components to prevent dust or other contaminants from entering the optical path, thereby maintaining the purity and stability of the light beam.

[0122] In summary, the workflow of the optical system includes: the beam emitted by the laser is adjusted by the laser beam shaper, and then divided into multiple beams by the beam splitter. Next, the beam is wavelength selected and polarization adjusted by the filter and wave plate, and enters the adjustable reflector system to guide the beam by changing the direction of the optical path. Finally, the laser beam is focused onto the substrate through the focusing lens, and the focus is adjusted in real time by the autofocus system to ensure high-precision lithography. Throughout the optical path, the optical path protection system always provides external protection to ensure the stable operation of the system. The above components work together to ensure that the laser beam can etch the holographic anti-counterfeiting pattern on the substrate with the highest accuracy and efficiency.

[0123] After determining the optimal focal length position, a second instruction is generated to instruct the vacuum adsorption system to start to fix the substrate. The function of the vacuum adsorption system is to firmly fix the substrate during the photolithography process to prevent it from any movement or vibration during the laser etching process. In a specific implementation, the stability of the substrate is crucial to the accuracy of the photolithography, because any slight movement may cause distortion or blurring of the photolithography pattern. Therefore, by starting the vacuum adsorption system, it can be ensured that the substrate remains stable throughout the photolithography process. To achieve this effect, the vacuum adsorption system generates a strong vacuum airflow at the bottom of the substrate to firmly adsorb the substrate on the workbench. For example, if the substrate size is 10 cm × 10 cm, the vacuum adsorption system will generate a uniform adsorption force on the entire substrate surface to ensure its stability.

[0124] Finally, a three-dimensional holographic anti-counterfeiting pattern is obtained by photolithography on the fixed substrate through a laser. The laser gradually etches the holographic anti-counterfeiting pattern on the substrate according to the previously set frequency, exposure angle and scanning path. The high energy density and fine control ability of the laser enable the lithography machine to form complex three-dimensional patterns on the substrate. The interaction between the laser and the substrate material produces a series of tiny interference fringes, which can show a three-dimensional effect under certain lighting conditions. By precisely controlling the exposure time and energy of the laser, the lithography machine can form different interference patterns at different depths of the substrate, thereby enhancing the anti-counterfeiting effect. For example, if the goal is to generate a holographic pattern with a depth effect, the laser can adjust its output power to etch different pattern levels at different depths.

[0125] After receiving the grayscale image, this embodiment automatically encodes the holographic anti-counterfeiting information into the grayscale image, and automatically adjusts the frequency and exposure angle range of the laser according to the spatial frequency and pattern complexity of the image. There is no need to manually export the grayscale image and import it into the lithography software, which reduces the complexity of the process and effectively saves operation time. At the same time, by acquiring the intensity of the reflected light on the substrate and the clarity of the interference pattern in real time, the optimal focal length position of the optical system is automatically determined, and the substrate is fixed according to the instructions generated by the optimal focal length, ensuring the precise alignment of the substrate and reducing the time for manual adjustment. In addition, the scanning path of the laser is automatically determined according to the fine pattern of the holographic anti-counterfeiting grayscale image, which further reduces the need for manual operation, improves production efficiency, and solves the complexity and inefficiency caused by manual operation in the existing process.

[0126] In one implementation of this embodiment, the first grayscale value of the grayscale image is modulated by the second grayscale value of the target grayscale image to embed the second grayscale value into the grayscale image to obtain a holographic anti-counterfeiting grayscale image, including the following steps:

[0127] S310, normalizing the first grayscale value to obtain a normalized first grayscale value, and normalizing the second grayscale value to obtain a normalized second grayscale value;

[0128] S320, using multiplication modulation to modulate the normalized second grayscale value by the normalized first grayscale value to obtain a third grayscale value;

[0129] S330, determining whether the grayscale value range of the third grayscale value exceeds the range of [0, 1];

[0130] S340, when the grayscale value range of the third grayscale value exceeds the range of [0, 1], clipping the grayscale value range of the third grayscale value so that the grayscale value range of the third grayscale value is within the range of [0, 1];

[0131] S350, synthesizing a holographic anti-counterfeiting grayscale image according to the third grayscale values ​​of all pixels.

[0132] First, define the grayscale image as , whose grayscale value is the first grayscale value. The target grayscale image is , whose grayscale value is the second grayscale value, contains holographic anti-counterfeiting information. The holographic anti-counterfeiting grayscale image is , whose grayscale value is the third grayscale value.

[0133] Normalizing the first grayscale value and the second grayscale value means normalizing the grayscale value range of the two images to [0,1] for subsequent calculations. Assuming that the original grayscale value range is [0,255], the normalization formula is:

[0134] ;

[0135] Get the normalized first grayscale image and the second grayscale image .

[0136] Then, the second gray value is modulated by the first gray value to form a third gray value by multiplication modulation. The modulation formula is:

[0137] ;

[0138] Wherein, k is a modulation coefficient, which is used to control the influence of the second gray value on the first gray value.

[0139] If k=1, then The influence is fully exerted on If k < 1, then The influence of is weakened. If k>1, then The impact is amplified.

[0140] In order to ensure that the grayscale value range after modulation is still within [0,1], if the grayscale value range of the third grayscale value exceeds the range [0,1], clipping is required. This can be achieved by the following operations:

[0141] ;

[0142] Restore the grayscale value of the cropped image to the range of [0,255]:

[0143] .

[0144] Finally, the third grayscale values ​​of all pixels form a holographic anti-counterfeiting grayscale image , this image contains the fusion information of the grayscale image and the target grayscale image, achieving the purpose of anti-counterfeiting. For example, assuming that the grayscale image A pixel value in is 200, and the target grayscale image The corresponding pixel value in is 50. After normalization:

[0145] , .

[0146] Select the modulation coefficient k=0.5, then the gray value after modulation is:

[0147] .

[0148] To restore the original range: , then the value of the pixel in the third grayscale image is 219.

[0149] This embodiment effectively embeds the anti-counterfeiting information of the target grayscale image into the original grayscale image through normalization processing and multiplication modulation, and ensures the visual quality of the image through cropping. In the generated holographic anti-counterfeiting grayscale image, the hidden anti-counterfeiting information is successfully embedded while maintaining the overall aesthetics and complexity of the image, significantly enhancing the anti-counterfeiting effect.

[0150] In one implementation of this embodiment, determining the frequency of the laser according to the spatial frequency and the pattern complexity includes the following steps:

[0151] S410, calculating the fundamental frequency of the laser according to the spatial frequency;

[0152] S420, performing correction calculation on the basic frequency according to the entropy value of the holographic anti-counterfeiting grayscale image and the density of the edge pixels to obtain the frequency of the laser.

[0153] First, according to the spectrum diagram of S240, the spatial frequency and entropy value of the holographic anti-counterfeiting grayscale image and the density of edge pixels are obtained. Since the frequency f of the laser is closely related to the average spatial frequency of the holographic anti-counterfeiting grayscale image, the basic frequency is:

[0154] ;

[0155] Where k1 is a proportional constant, f1 is the fundamental frequency, and f2 is the average spatial frequency.

[0156] After that, the frequency is adjusted according to the complexity of the pattern. Images with high pattern complexity require higher laser frequencies to depict image details more finely. The basic laser frequency can be adjusted by the following formula:

[0157] ;

[0158] Among them, f3 is the frequency of the laser, k2 is another adjustment coefficient, and H is the entropy of the image. The higher the entropy value, the greater the adjustment amplitude of the laser frequency.

[0159] If the edge pixel density is higher, it means that there are more fine structures in the image, so a higher laser frequency is required. The laser frequency can be further corrected according to the edge pixel density:

[0160] ;

[0161] Among them, f3 is the final frequency of the laser, k3 is the corresponding adjustment coefficient, and D is the edge pixel density.

[0162] This embodiment calculates the spatial frequency and pattern complexity of the image and adjusts the frequency of the laser to ensure that the fine pattern of the holographic anti-counterfeiting grayscale image is accurately depicted during the manufacturing process.

[0163] In one implementation of this embodiment, determining the exposure angle range of the laser and the scanning path of the laser on the substrate according to the fine pattern of the holographic anti-counterfeiting grayscale image includes the following steps:

[0164] S510, determining the spatial frequency and directional information of the fine pattern through the spectrum of the holographic anti-counterfeiting grayscale image, wherein the spatial frequency of the fine pattern is consistent with the spatial frequency of the holographic anti-counterfeiting grayscale image, and the directional information includes the main frequency direction of the spectrum;

[0165] S520, dividing the fine pattern into a high-frequency pattern and a low-frequency pattern according to the spatial frequency of the fine pattern;

[0166] S530, determining the angle offset of the laser according to the spatial frequency and the pattern complexity;

[0167] S540, determining an initial exposure angle range of the laser according to the main frequency direction and the angle offset of the laser;

[0168] S550, correcting the initial exposure angle range according to the high-frequency pattern and the low-frequency pattern to obtain an exposure angle range of the laser;

[0169] S560, identifying the type of the micro-pattern, and determining the scanning path of the laser on the substrate according to the type of the micro-pattern, wherein the type of the micro-pattern includes a linear pattern, annular pattern and / or a spiral pattern, when the type of the micro-pattern is a linear pattern, the scanning path is a parallel linear scanning path, when the type of the micro-pattern is annular pattern or a spiral pattern, the scanning path is a spiral scanning path, when the type of the micro-pattern is a combination of a linear pattern and annular pattern, the scanning path is a parallel linear scanning path and a spiral scanning path, and when the type of the micro-pattern is a combination of a linear pattern and a spiral pattern, the scanning path is a parallel linear scanning path and a spiral scanning path.

[0170] In this embodiment, the directionality of the pattern is analyzed using the spectrum after Fourier transformation. The high-frequency component in a specific direction indicates that the pattern has obvious details in that direction. The main frequency direction of the pattern can be quantified and analyzed using the radial average power spectrum or the directional gradient histogram. The main frequency direction is the direction with the most concentrated energy in the spectrum, representing the most significant structural direction in the image.

[0171] According to the spatial frequency of fine patterns, they are divided into high-frequency patterns and low-frequency patterns. High-frequency patterns correspond to the parts of the image that change faster and have more detailed structures, while low-frequency patterns correspond to areas that change slower and have smoother structures. The division of spatial frequency can be achieved by setting a threshold. The parts with frequencies above the threshold are classified as high-frequency patterns, and the parts with frequencies below the threshold are classified as low-frequency patterns.

[0172] When determining the angle offset of the laser, areas with high spatial frequencies often require more precise exposure angle control, while patterns with high complexity may require multiple exposures at multiple angles to ensure the clarity and anti-counterfeiting effect of the holographic pattern. The angle offset can be determined by the spatial frequency and pattern complexity.

[0173] The angle offset can be obtained through a preset image recognition algorithm.

[0174] First, based on the main directionality and spatial frequency of the fine pattern, the exposure angle range of the laser is preliminarily determined. The exposure angle range covers all important directional features in the pattern. The main frequency direction To adjust:

[0175] ;

[0176] in, It is the angular offset determined by the pattern complexity and spatial frequency.

[0177] Since high-frequency patterns usually require a more precise exposure angle range, while low-frequency patterns allow for a wider angle range, the angle range can be adjusted by weighted averaging of the frequency distribution:

[0178] ;

[0179] Where W is the weight factor, For direction The Fourier transform magnitude of .

[0180] The scanning path may be determined according to the type of the fine pattern, and the scanning path includes a linear scanning path, a spiral scanning path, or a pattern-based adaptive scanning path.

[0181] For linear patterns, parallel linear scanning is usually used; for annular or spiral patterns, a spiral scanning path is usually selected. In addition, the scanning path can be adaptively selected according to the type of the micro-pattern. That is, the type of the micro-pattern includes linear pattern, annular pattern and / or spiral pattern. When the type of the micro-pattern is a linear pattern, the scanning path is a parallel linear scanning path. When the type of the micro-pattern is annular pattern or spiral pattern, the scanning path is a spiral scanning path. When the type of the micro-pattern is a combination of a linear pattern and annular pattern, the scanning path is a parallel linear scanning path and a spiral scanning path. When the type of the micro-pattern is a combination of a linear pattern and a spiral pattern, the scanning path is a parallel linear scanning path and a spiral scanning path.

[0182] In a specific implementation, an adaptive scanning strategy may be adopted to adjust the density and speed of the scanning path according to the change of the local spatial frequency of the pattern.

[0183] Scan speed The local spatial frequency of the pattern can be Dynamic Adjustment:

[0184] ;

[0185] The higher the frequency, the slower the scanning speed should be to ensure accurate depiction of high-frequency details. For example, suppose there is a holographic anti-counterfeiting grayscale image with a main frequency direction , and contains significant high-frequency components. First, the exposure angle range is preliminarily determined to be According to the high frequency components The angle range is further refined to After that, a linear sweep based path is selected, parallel to the main frequency direction The scanning speed is adjusted adaptively, and the scanning speed is slower in areas with higher frequencies to ensure accurate depiction of high-frequency details.

[0186] This embodiment determines the exposure angle range and scanning path of the laser by analyzing the spatial frequency and directionality of the holographic anti-counterfeiting grayscale image, thereby optimizing the operating parameters of the laser and achieving high-quality holographic anti-counterfeiting image production.

[0187] In one implementation of this embodiment, after determining the exposure angle range of the laser and the scanning path of the laser on the substrate according to the fine pattern of the holographic anti-counterfeiting grayscale image, the following steps are included:

[0188] S610 , using an adaptive scanning strategy to adjust the density and speed of the scanning path according to the change of the spatial frequency of the fine pattern.

[0189] Implementing an adaptive scanning strategy to adjust the density and speed of the scanning path according to the spatial frequency changes of the fine pattern can more accurately depict the pattern details in the holographic anti-counterfeiting image manufacturing process. First, the image is converted from the spatial domain to the frequency domain using Fourier transform to obtain a spectrum diagram. Each frequency point represents the details of the corresponding scale in the image.

[0190] Then use the sliding window to perform local analysis on the image and calculate the average frequency or local frequency peak in each window. The size of the window can be adjusted according to the detailed changes of the pattern. A two-dimensional distribution map of spatial frequency changes is obtained for subsequent scanning path optimization. After that, the basic density of the scanning path is determined. The initial scanning path can be a regular grid, parallel linear scanning, spiral path, etc. The specific choice depends on the overall morphology of the pattern. The density of the basic path is determined by the initial step size. and In high-frequency areas, the density of scanning paths is increased to ensure that small details are captured. In low-frequency areas, the path density is reduced to improve scanning efficiency. Path Density Adjustment Factor It can be defined as:

[0191] ;

[0192] Among them, k d is the adjustment coefficient, which is used to control the amplitude of density adjustment. The scan step after adjustment is:

[0193] ;

[0194] That is, the step size in the high-frequency area becomes smaller and the path density becomes larger.

[0195] The basic scanning speed v0 can be set according to the power of the laser, the material properties and the complexity of the initial pattern. The high-frequency area requires a slower scanning speed to ensure the fine characterization of the pattern. The low-frequency area can speed up the scanning speed and improve efficiency. The inverse relationship between the scanning speed v(x,y) and the local spatial frequency f(x,y) is:

[0196] ;

[0197] Among them, k v It is a coefficient that controls the speed adjustment range. The higher the frequency in the high-frequency area, the slower the scanning speed. In specific implementation, the scanning path and speed can be adjusted by collecting the frequency characteristic data of the current scanning area in real time.

[0198] This embodiment adopts an adaptive scanning strategy, which can significantly improve the manufacturing accuracy of holographic anti-counterfeiting images by real-time analysis of the spatial frequency changes of the pattern and dynamically adjust the density and speed of the scanning path, while maintaining high efficiency and ensuring accurate depiction of pattern details.

[0199] In one implementation of this embodiment, determining the optimal focal length position of the optical system according to the intensity of the reflected light and the clarity of the interference pattern on the substrate includes the following steps:

[0200] S710, starting from an initial focal length position of the optical system, gradually adjusting the focal length of the optical system according to a preset unit step length, and acquiring the intensity of the reflected light and the clarity of the interference pattern on the substrate at each focal length position;

[0201] S720, comparing the intensity of the reflected light at adjacent focal length positions and the clarity of the interference pattern on the substrate at all focal length positions, and determining a trend change of the intensity of the reflected light and the clarity of the interference pattern on the substrate;

[0202] S730: Determine an optimal focal length position according to the trend change, wherein a gain of the trend change before and after the optimal focal length position is less than a preset threshold.

[0203] The step-by-step scanning method is to gradually adjust the focal length, record the reflected light intensity and interference pattern clarity at each position in turn, and then find the optimal focal length position. Starting from the initial focal length position, gradually adjust the focal length of the optical system (for example, adjust a small step each time). ).

[0204] At each focal length position fi, the reflected light intensity is measured and calculate the interference pattern clarity , and compare adjacent focal length positions The reflected light intensity and clarity values ​​are used to determine trend changes:

[0205] if and , then continue to adjust the focal length forward;

[0206] if or , indicating that the focus position is over-adjusted and should be retracted or stopped.

[0207] When a position fi is found, the focal length changes before and after this position result in and When the gain decreases or there is no obvious gain, fi is the optimal focal length position.

[0208] For example, the initial focal position is , each time increase .

[0209] The reflected light intensity sequence is measured: , , , , .

[0210] Discover After the intensity decreases, stop scanning and confirm For the best focal length.

[0211] This embodiment can effectively determine the optimal focal length position of the optical system through a step-by-step scanning method, without the need for complex optimization algorithms, relying on basic measurements and data analysis, and reducing computing power.

[0212] In one implementation of this embodiment, the vacuum adsorption system includes an adsorption pressure sensor, and generates a second instruction according to the optimal focal length position, including the following steps:

[0213] S810, during the process of vacuum adsorption by the vacuum adsorption system, obtaining the vacuum pressure of the vacuum adsorption system in real time through the adsorption pressure sensor;

[0214] S820, matching the best focal length position with each target area of ​​the substrate, and determining the focal length of each target area, the substrate including at least two target areas;

[0215] S830, determining a focal length change amount of an adjacent target area according to the focal length of each target area;

[0216] S840, when the focal length variation is less than or equal to a preset variation, determining that the substrate is flat;

[0217] S850: When the substrate is flat, determine a pressurization operation or a depressurization operation for each target area according to the focal length of each target area, and generate a second instruction according to the pressurization operation or the depressurization operation for each target area.

[0218] Figure 4 A schematic diagram of the structure of a vacuum adsorption system provided in an embodiment of the present application is shown. Figure 4 As shown, the vacuum adsorption system includes an adsorption pressure sensor, a vacuum pump, a vacuum pipeline and valve system, an adsorption table, a sealing device, a vacuum gauge, etc.

[0219] The vacuum pump is responsible for generating the required negative pressure (vacuum state). In the holographic anti-counterfeiting printing lithography machine, the vacuum pump maintains the vacuum state of the adsorption table by extracting air, thereby ensuring that the substrate or other workpiece can be firmly adsorbed on the workbench.

[0220] The vacuum pipeline connects the vacuum pump, adsorption platform and adsorption pressure sensor, and is responsible for transmitting negative pressure. The valve system usually includes a manual or automatic solenoid valve to control the opening and closing of the vacuum pipeline, thereby adjusting the vacuum degree in different areas. The vacuum state of the adsorption area can be precisely controlled by adjusting the opening of the valve.

[0221] The adsorption table is the area where the workpiece is directly placed. It is usually designed with multiple vacuum adsorption holes. The arrangement and number of holes are optimized according to the shape and size of the workpiece.

[0222] The sealing device is usually made of flexible materials such as rubber rings and polyurethane strips, and fits tightly between the edge of the adsorption table and the bottom surface of the workpiece. The sealing device can effectively prevent air from entering the adsorption area and maintain the vacuum state of the system.

[0223] Vacuum gauge and display panel: The vacuum gauge is used to display the vacuum degree in the system in real time, helping the operator to monitor the operating status of the system. The display panel is usually integrated into the operation interface to display various parameters of the vacuum adsorption system, such as vacuum degree, pump status, valve opening and closing status, etc.

[0224] In the photolithography process, adsorption pressure is crucial to ensure the flatness and fixation of the substrate. After determining the optimal focal length position, the surface shape and flatness of the substrate can be evaluated based on the optimal focal length position. During the vacuum adsorption process, the adsorption pressure sensor can monitor the vacuum pressure of the vacuum adsorption system in real time to evaluate the adsorption effect and whether the substrate is fixed flatly on the workbench.

[0225] Secondly, the focal length data is matched with different target areas of the substrate to analyze the change of focal length, which is used to evaluate the flatness of the substrate. If the focal length varies greatly in different areas, it may indicate that the substrate fails to fit completely flat on the workbench. Combined with the data of the adsorption pressure sensor, it can be determined whether the current adsorption pressure is sufficient to completely fix the substrate. If the pressure is insufficient, the substrate may be warped in certain areas, affecting the stability of the focal length. According to the feedback from the focal length data and the pressure sensor, the vacuum pressure of the adsorption system can be automatically adjusted. The specific method includes: if the focal length of certain target areas deviates from the optimal value, it may mean that the pressure is insufficient, and the vacuum pressure is automatically increased to ensure that the substrate fits completely. If the pressure is too high, the substrate may be deformed or too close to the workbench, and the vacuum pressure is reduced at this time. During the entire lithography process, this embodiment can continuously monitor the changes in focal length data and adsorption pressure, and dynamically adjust them to ensure that the substrate is always in the best focal length and adsorption state.

[0226] Specifically, the adsorption pressure sensor is usually placed in the middle of the vacuum pipeline and can directly contact the air pressure in the pipeline. The internal structure of the sensor usually contains a sensitive element. When the negative pressure (vacuum) state changes, the resistance, piezoelectric properties or photoelectric properties of the sensitive element will change accordingly, and then output the corresponding electrical signal. By monitoring these signals in real time, it is possible to quickly determine whether the vacuum pressure in the system meets the set adsorption requirements. For example, if the target value of the vacuum pressure is set to -0.08MPa, when the actual measured pressure is -0.07MPa, the air pressure in the pipeline can be further reduced by adjusting the working intensity of the vacuum pump or adjusting the valve to ensure the adsorption effect.

[0227] In laser ranging, a laser beam of a specific wavelength is emitted to illuminate the target area, and the reflected light is received to calculate the precise distance of the area. The focal length of the target point is calculated, where c is the speed of light and t is the time required for light to propagate. By repeatedly applying this process to each target area of ​​the substrate, the focal length of different areas can be obtained one by one. The reason for ensuring the best focal length is that if the focal length is not accurate, it will cause errors in the system during operation due to unclear targets. By accurately measuring the focal length of each area, the accuracy of the optical system can be effectively guaranteed, thereby improving the stability and production quality of the entire system.

[0228] According to the focal length of each target area, the focal length change of the adjacent target area is calculated. This step is achieved by calculating the focal length difference of the adjacent areas. The specific method is to use the difference in the focal length values ​​of the adjacent areas to represent the focal length change, which is set as , where d1 and d2 are the focal lengths of two adjacent target areas. The calculation of the focal length change can determine whether there is a height difference or unevenness on the substrate surface. If the focal length change is large, it indicates that the height of the substrate surface is uneven; otherwise, it indicates that the substrate is relatively flat. By comparing the focal length changes between multiple target areas, the height difference of the substrate surface can be quickly identified.

[0229] When the focal length variation is less than or equal to the preset variation, the substrate can be judged to be flat. The preset variation is a threshold value set based on experience and process requirements. For example, if the preset variation is 0.05 mm, and the focal length variations of adjacent target areas are all less than or equal to 0.05 mm, the substrate is considered to be sufficiently flat. When the substrate is judged to be flat, the pressurization or decompression operation for each target area is determined based on the focal length of each target area.

[0230] In the specific implementation process, the pressure regulating device of the vacuum adsorption system is controlled to make appropriate adjustments according to the focal length of each area. For example, if the focal length of a certain area is in the optimal state, there is no need to adjust the pressure; for areas with high focal length, the adsorption pressure can be reduced to make it closer to the adsorption surface. Conversely, for areas with low focal length, the pressure can be appropriately increased to keep the distance from the substrate consistent. The process of adjusting the pressure can be achieved by adjusting the output power of the vacuum pump or changing the air pressure of the adsorption pipeline through the solenoid valve to achieve the effect of uniform adsorption of each target area.

[0231] Finally, a second instruction is generated based on the pressurization or decompression operation of each target area. The second instruction is transmitted to a control unit such as a PLC (programmable logic controller) or an industrial computer in the form of a digital signal. After receiving the instruction, the control unit directs the coordinated action of components such as vacuum pumps, valves, and pressure sensors to achieve precise pressure control of each area. For example, the PLC will automatically calculate and output the corresponding current or voltage signal based on the data fed back by the sensor to drive the booster pump or adjust the solenoid valve, thereby achieving precise pressurization or decompression of the target area. The above process improves the response speed and control accuracy of the entire vacuum adsorption system, and effectively ensures the continuity and efficiency of production.

[0232] In a specific implementation, if the focus still cannot be stabilized at the optimal position after adjusting the adsorption pressure, an alarm is issued to prompt the operator to check the status of the substrate or the hardware of the lithography machine. In addition, if it is detected that the adsorption system cannot maintain the necessary pressure, the lithography process is automatically terminated to avoid damage to the substrate or equipment.

[0233] This embodiment can significantly improve the accuracy and stability of lithography by combining the focal position data and the pressure sensor data to control the adsorption pressure after determining the optimal focal length, significantly improve the intelligence level of the lithography machine, and make the production process more efficient, accurate and reliable.

[0234] The present application also provides a lithography device for holographic anti-counterfeiting printing, comprising:

[0235] a memory configured to store instructions; and

[0236] The processor is configured to call instructions from the memory and implement the above-mentioned lithography method for holographic anti-counterfeiting printing when executing the instructions.

[0237] The present application also provides a lithography machine, including:

[0238] The above-mentioned lithography device for holographic anti-counterfeiting printing;

[0239] Lasers;

[0240] Optical system;

[0241] Vacuum adsorption system.

[0242] The present application also provides a lithography system for holographic anti-counterfeiting printing, comprising:

[0243] The above-mentioned lithography machine.

[0244] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems or computer program products. Therefore, the present application may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0245] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of the processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0246] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0247] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0248] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0249] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0250] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0251] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0252] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A photolithography method for holographic anti-counterfeiting printing, characterized in that: Applied to a photolithography machine, the photolithography machine includes a laser, an optical system and a vacuum adsorption system, and the method includes: In response to receiving at least one grayscale image, obtaining a first grayscale value of the grayscale image; Converting the preset holographic anti-counterfeiting information into a target grayscale image, and acquiring a second grayscale value of the target grayscale image; Modulating the first grayscale value of the grayscale image by the second grayscale value of the target grayscale image to embed the second grayscale value into the grayscale image, thereby obtaining a holographic anti-counterfeiting grayscale image, wherein the grayscale value of the holographic anti-counterfeiting grayscale image is a third grayscale value; Performing Fourier transformation on the holographic anti-counterfeiting grayscale image to obtain a frequency spectrum of the holographic anti-counterfeiting grayscale image; Determine the frequency distribution of the holographic anti-counterfeiting grayscale image according to the frequency spectrum, and perform weighted averaging on the frequency distribution of the holographic anti-counterfeiting grayscale image to calculate the spatial frequency of the holographic anti-counterfeiting grayscale image; determining the pattern complexity of the holographic anti-counterfeiting grayscale image according to the third grayscale value of the holographic anti-counterfeiting grayscale image; determining the frequency of the laser according to the spatial frequency and the pattern complexity, wherein the holographic anti-counterfeiting grayscale image is composed of fine patterns; Determining the exposure angle range of the laser and the scanning path of the laser on the substrate according to the fine pattern of the holographic anti-counterfeiting grayscale image; In response to receiving a first instruction, according to the frequency of the laser and the exposure angle range, controlling the laser to scan the surface of the substrate according to the scanning path, so as to obtain in real time the intensity of the reflected light on the substrate and the clarity of the interference pattern on the substrate, wherein the first instruction is used to instruct the lithography machine to scan the surface of the substrate; Determining the optimal focal length position of the optical system according to the intensity of the reflected light and the clarity of the interference pattern on the substrate; generating a second instruction according to the optimal focal length position, wherein the second instruction is used to instruct the vacuum adsorption system to start so as to fix the substrate; The laser is used to perform photolithography on the fixed substrate to obtain a three-dimensional holographic anti-counterfeiting pattern.

2. The method according to claim 1, characterized in that The determining the pattern complexity of the holographic anti-counterfeiting grayscale image according to the third grayscale value of the holographic anti-counterfeiting grayscale image comprises: According to the third grayscale value, the entropy value and the density of edge pixels of the holographic anti-counterfeiting grayscale image are calculated, wherein the entropy value and the density of edge pixels of the holographic anti-counterfeiting grayscale image are used to characterize the pattern complexity of the holographic anti-counterfeiting grayscale image.

3. The method according to claim 1, characterized in that The method of modulating the first grayscale value of the grayscale image by the second grayscale value of the target grayscale image to embed the second grayscale value into the grayscale image to obtain a holographic anti-counterfeiting grayscale image includes: Normalizing the first grayscale value to obtain a normalized first grayscale value, and normalizing the second grayscale value to obtain a normalized second grayscale value; Using multiplication modulation, the second grayscale value after normalization is modulated by the first grayscale value after normalization to obtain the third grayscale value; Determine whether the grayscale value range of the third grayscale value exceeds the range of [0,1]; When the grayscale value range of the third grayscale value exceeds the range of [0, 1], clipping the grayscale value range of the third grayscale value so that the grayscale value range of the third grayscale value is within the range of [0, 1]; The holographic anti-counterfeiting grayscale image is synthesized according to the third grayscale values ​​of all pixels.

4. The method according to claim 2, characterized in that: Determining the frequency of the laser according to the spatial frequency and the pattern complexity comprises: Calculating the fundamental frequency of the laser according to the spatial frequency; The basic frequency is corrected and calculated according to the entropy value of the holographic anti-counterfeiting grayscale image and the density of edge pixels to obtain the frequency of the laser.

5. The method according to claim 1, characterized in that The step of determining the exposure angle range of the laser and the scanning path of the laser on the substrate according to the fine pattern of the holographic anti-counterfeiting grayscale image comprises: Determining the spatial frequency and directional information of the fine pattern through the spectrum of the holographic anti-counterfeiting grayscale image, wherein the spatial frequency of the fine pattern is consistent with the spatial frequency of the holographic anti-counterfeiting grayscale image, and the directional information includes the main frequency direction of the spectrum; dividing the fine pattern into a high-frequency pattern and a low-frequency pattern according to the spatial frequency of the fine pattern; determining an angular offset of the laser according to the spatial frequency and the pattern complexity; Determining an initial exposure angle range of the laser according to the main frequency direction and the angle offset of the laser; Correcting the initial exposure angle range according to the high-frequency pattern and the low-frequency pattern to obtain an exposure angle range of the laser; Identify the type of the micro-pattern, and determine the scanning path of the laser on the substrate according to the type of the micro-pattern, wherein the type of the micro-pattern includes a linear pattern, an annular pattern and / or a spiral pattern, when the type of the micro-pattern is the linear pattern, the scanning path is a parallel linear scanning path, when the type of the micro-pattern is the annular pattern or the spiral pattern, the scanning path is a spiral scanning path, when the type of the micro-pattern is a combination of the linear pattern and the annular pattern, the scanning path is a parallel linear scanning path and the spiral scanning path, and when the type of the micro-pattern is a combination of the linear pattern and the spiral pattern, the scanning path is a parallel linear scanning path and the spiral scanning path.

6. The method according to claim 5, characterized in that After determining the exposure angle range of the laser and the scanning path of the laser on the substrate according to the fine pattern of the holographic anti-counterfeiting grayscale image, the method further includes: An adaptive scanning strategy is adopted to adjust the density and speed of the scanning path according to the change of the spatial frequency of the fine pattern.

7. The method according to claim 1, characterized in that Determining the optimal focal length position of the optical system according to the intensity of the reflected light and the clarity of the interference pattern on the substrate comprises: Starting from an initial focal length position of the optical system, gradually adjusting the focal length of the optical system according to a preset unit step length, and acquiring the intensity of the reflected light and the clarity of the interference pattern on the substrate at each focal length position; At all focal length positions, comparing the intensity of the reflected light and the clarity of the interference pattern on the substrate at adjacent focal length positions, and determining the trend change of the intensity of the reflected light and the clarity of the interference pattern on the substrate; An optimal focal length position is determined according to the trend change, wherein a gain of the trend change before and after the optimal focal length position is less than a preset threshold.

8. The method according to claim 1, characterized in that The vacuum adsorption system includes an adsorption pressure sensor, and the second instruction is generated according to the optimal focal length position, including: During the vacuum adsorption process of the vacuum adsorption system, the vacuum pressure of the vacuum adsorption system is obtained in real time through the adsorption pressure sensor; Corresponding the optimal focal length position to each target area of ​​the substrate, and determining the focal length of each target area, wherein the substrate includes at least two target areas; Determining a focal length change of an adjacent target area according to the focal length of each target area; When the focal length variation is less than or equal to a preset variation, determining that the substrate is flat; When the substrate is flat, a pressurization operation or a depressurization operation for each target area is determined according to the focal length of each target area, and a second instruction is generated according to the pressurization operation or the depressurization operation for each target area.

9. A lithography device for holographic anti-counterfeiting printing, characterized in that: include: a memory configured to store instructions; as well as A processor is configured to call the instructions from the memory and implement the lithography method for holographic anti-counterfeiting printing according to any one of claims 1 to 8 when executing the instructions.

10. A photolithography machine, characterized in that: include: A lithography apparatus for holographic anti-counterfeiting printing according to claim 9; Lasers; Optical system; Vacuum adsorption system.

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