Titanium substrate nano-holographic anti-counterfeiting structural color and composite laser processing method and application thereof

Abstract

The application relates to the field of anti-counterfeiting technology and discloses a titanium substrate nano-holographic anti-counterfeiting structural color and a composite laser processing method and application thereof, wherein the method comprises the following steps: providing a titanium metal substrate; adopting a wide pulse width laser light source to pretreat the titanium metal substrate, so that a self-flow layer is formed on the surface of the titanium metal substrate; adopting an ultrafast laser light source to scan and process the titanium metal substrate with the self-flow layer in accordance with an anti-counterfeiting encryption icon, nano-grating structures with extractable periods are induced, and the titanium substrate nano-holographic anti-counterfeiting structural color is obtained. The technical scheme provided by the application can ensure the quality and environmental friendliness of anti-counterfeiting holographic structural color processing.

Description

Technical Field

[0001] This application relates to the field of anti-counterfeiting technology, and in particular to a titanium-based nano-iridescent anti-counterfeiting structural color and its composite laser processing method and application. Background Technology

[0002] Iridescent structural colors are physical colors generated by micro- and nano-sized gratings, formed through the interference and diffraction of light. They offer high anti-counterfeiting and personalization capabilities, making them suitable for anti-counterfeiting labels, bank cards, and identification documents. Compared to traditional laser direct writing, laser-induced technology can process sub-micron-level fine gratings on metal surfaces, achieving richer color effects. However, its processing quality is highly dependent on the smoothness and cleanliness of the substrate surface. Currently, strong acids such as sulfuric acid, hydrochloric acid, or hydrofluoric acid are commonly used in industry to treat metals to ensure surface quality. However, these chemicals pose serious health and safety risks, while also increasing processing complexity and cost.

[0003] Therefore, ensuring the quality and environmental friendliness of anti-counterfeiting iridescent structural color processing is a pressing technical problem that needs to be solved. Summary of the Invention

[0004] This application provides a titanium-based nano-iridescent anti-counterfeiting structural color and its composite laser processing method and application, which achieves the technical effect of ensuring the quality and environmental friendliness of the anti-counterfeiting iridescent structural color processing.

[0005] To achieve the above objectives, the main technical solutions adopted in this application include:

[0006] In a first aspect, embodiments of this application provide a composite laser processing method for titanium substrate nano-iridescent anti-counterfeiting structural colors, the method comprising:

[0007] Provides titanium metal substrate;

[0008] The titanium metal substrate is pretreated using a wide-pulse laser light source to form a self-flowing layer on the surface of the titanium metal substrate;

[0009] Using an ultrafast laser light source, the anti-counterfeiting encryption icon is scanned and processed on a titanium metal substrate with a self-flowing layer, inducing a nano-grating structure with an extractable period, thus obtaining a nano-iridescent anti-counterfeiting structural color on the titanium substrate.

[0010] This embodiment provides a composite laser processing method for anti-counterfeiting structural colors on a titanium substrate. By employing a wide-pulse laser source and an ultrafast laser source, the processing quality of the anti-counterfeiting iridescent structural colors on the titanium metal substrate surface can be effectively guaranteed. The wide-pulse laser source is used to pre-treat the titanium metal substrate, forming a self-flowing layer to avoid excessive oxidation, thereby ensuring the stability of the surface structure and the accuracy of subsequent processing. Then, the ultrafast laser source scans and processes the titanium metal substrate with the self-flowing layer, precisely inducing a periodic nanograting structure, ensuring the clarity and uniqueness of the iridescent structural colors, and effectively preventing counterfeiting. Furthermore, the energy-saving and environmentally friendly advantages of laser processing are also significant. Laser processing does not require the use of chemicals, reducing waste and by-products, significantly reducing environmental pollution, while improving processing efficiency and reducing energy consumption. Therefore, this embodiment not only ensures high-quality anti-counterfeiting effects but also possesses strong environmental friendliness.

[0011] In one embodiment, the roughness of the self-flowing layer is less than or equal to 30 nm.

[0012] This embodiment significantly improves the processing quality and environmental friendliness of the anti-counterfeiting iridescent structural color by controlling the roughness of the self-flowing layer to below 30 nm. First, lower surface roughness ensures the precise generation of the grating structure during laser processing, thereby improving the stability and vividness of the iridescent color and increasing the difficulty of anti-counterfeiting. Second, a smooth surface reduces light scattering, ensuring a more durable anti-counterfeiting effect, and enhancing corrosion and oxidation resistance, making the structural color less prone to fading over long-term use. Furthermore, lower roughness makes laser processing more efficient, reducing energy waste and waste generation, thus reducing environmental impact and dependence on chemicals, further improving the environmental friendliness of the processing process.

[0013] In one embodiment, the wide pulse width laser source has a pulse width of 2-120 ns.

[0014] This embodiment employs a wide-pulse laser source with a pulse width of 2-120ns, which can improve environmental friendliness while ensuring the processing quality of the anti-counterfeiting iridescent structural color. By precisely controlling the laser pulse width, shorter pulses (2-20ns) have higher peak power, enabling rapid heating of the material surface and precise formation of microstructures in a shorter time. This helps avoid excessive heat transfer, ensuring the precision and surface quality of laser processing. Longer pulses (40-120ns), on the other hand, allow for a longer heating time, enabling more uniform heating of the material surface and forming a self-flowing layer, which contributes to the optimization of surface morphology.

[0015] In one embodiment, the scanning interval of the wide-pulse laser source or the ultrafast laser source is less than or equal to the spot diameter.

[0016] This embodiment, by employing a wide-pulse-width laser source or the aforementioned ultrafast laser source and designing the scanning interval to be less than or equal to the spot diameter, can significantly improve the processing quality of the anti-counterfeiting iridescent structural colors. The smaller scanning interval ensures higher laser processing precision, avoiding color unevenness and structural distortion caused by excessively large spot spacing, thus guaranteeing the clarity and stability of the anti-counterfeiting effect. Furthermore, this processing method reduces thermal effects, lowers material thermal damage and energy waste, contributing to environmental protection goals while reducing material waste and improving processing efficiency. Through a high-precision, low-energy processing procedure, not only is the anti-counterfeiting capability of the anti-counterfeiting label enhanced, but its wear resistance and long-term stability are also improved.

[0017] In one embodiment, when the wide-pulse laser source is a MOPA laser source, the laser output power of the wide-pulse laser source is 20-90W, the repetition frequency is 2600kHz, and the scanning speed is 7000-14000mm / s.

[0018] This embodiment utilizes a MOPA laser light source, achieving precise laser control under conditions of 20-90W laser output power, 2600kHz repetition rate, and 7000-14000mm / s scanning speed. This ensures high quality and environmental friendliness in the processing of anti-counterfeiting iridescent structural colors. Precise adjustment of laser power prevents overheating or scorching during processing, guaranteeing the uniformity and clarity of the structural colors. High repetition rate and high-speed scanning ensure improved processing efficiency while reducing energy waste and thermal effects, thus increasing production efficiency. Compared to traditional chemical anti-counterfeiting technologies, laser processing eliminates the need for chemical substances, avoiding the emission of hazardous waste and resulting in a lower environmental impact. This efficient and environmentally friendly laser processing technology not only improves the quality and stability of anti-counterfeiting labels but also ensures the sustainability of the production process.

[0019] In one embodiment, when the wide-pulse-width laser source is a GHz femtosecond laser source in Burst mode, the laser output power of the wide-pulse-width laser source is 15W, the scanning speed is 1800-12000mm / s, the repetition frequency is 500kHz, and in Burst mode, the pulse width of a pulse train is 120ns.

[0020] This embodiment employs a GHz femtosecond laser source in Burst mode, combined with an output power of 15W, a scanning speed of 1800-12000 mm / s, a repetition frequency of 500 kHz, and a pulse width of 120 ns. This allows for precise control of heat accumulation and thermal diffusion effects, promoting uniform melting and flow on the surface of the titanium substrate to form the desired self-flowing layer. This laser processing method not only improves processing accuracy and speed but also optimizes surface quality, ensuring environmental friendliness while meeting the needs of precision processing such as anti-counterfeiting and microstructure applications.

[0021] In one embodiment, the ultrafast laser source is a picosecond laser source or a femtosecond laser source; wherein, when the ultrafast laser source is a picosecond laser source, the control current of the ultrafast laser source is 2.1-3.2A, the repetition frequency is 20-30kHz, and the scanning speed is 5-400mm / s.

[0022] This embodiment employs a picosecond laser light source for processing anti-counterfeiting iridescent structural colors, achieving high-precision and high-quality processing results. By adjusting the laser control current within the range of 2.1A to 3.2A, the repetition frequency between 20-30kHz, and the scanning speed between 5-400mm / s, the energy of the laser pulse and the processing speed can be precisely controlled, thereby forming a micro-grating structure on the metal surface. Due to the short duration of the picosecond laser pulse, heat diffusion is effectively controlled, avoiding excessive heat-affected zones and ensuring the high precision and stability of the iridescent structure. This precise processing not only improves the anti-counterfeiting effect but also ensures the uniformity and visual appeal of the structural colors. Furthermore, the laser processing generates less heat, reducing exhaust emissions and material waste, thus exhibiting high environmental friendliness. Therefore, this technology ensures high-quality processing of anti-counterfeiting iridescent structural colors while achieving energy-efficient utilization and environmental friendliness, meeting the requirements of green environmental protection.

[0023] In one embodiment, when the control current of the ultrafast laser source is 2.1-2.5A, the scanning speed is 5-10mm / s;

[0024] With a control current of 2.8-3.2A for the ultrafast laser source, the scanning speed is 200-400 mm / s.

[0025] This embodiment utilizes a lower current of 2.1-2.5A and a lower scanning speed of 5-10mm / s, primarily suitable for machining tasks requiring extremely high precision, ensuring the fineness and uniformity of the microstructure. Conversely, a higher current of 2.8-3.2A combined with a high-speed scan of 200-400mm / s is suitable for efficiently and quickly processing anti-counterfeiting iridescent color printing on larger areas or deeper structures, maintaining processing efficiency while controlling heat-affected zones and material damage. These two sets of parameters can be flexibly adjusted according to actual needs to achieve different processing effects.

[0026] Secondly, embodiments of this application provide a titanium-based nano-iridescent anti-counterfeiting structural color, which is prepared using the composite laser processing method for the titanium-based nano-iridescent anti-counterfeiting structural color described above.

[0027] Thirdly, this application provides an application of a titanium-based nano-iridescent anti-counterfeiting structural color. The grating period of the nano-grating structure in the titanium-based nano-iridescent anti-counterfeiting structural color or the titanium-based nano-iridescent anti-counterfeiting structural color prepared by the above method is extracted, and a laser parameter-period mapping database is established for anti-counterfeiting verification. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 A flowchart illustrating a composite laser processing method for a titanium substrate nano-iridescent anti-counterfeiting structural color, provided in this application embodiment;

[0030] Figure 2 Comparison images of Example 1 and Comparative Example 1 taken under the same shooting conditions for this application;

[0031] Figure 3 This is the FFT result of Comparative Example 1 of this application;

[0032] Figure 4 This is the FFT result of Example 1 of this application;

[0033] Figure 5 Comparison images of Example 2 and Comparative Example 2 taken under the same shooting conditions, provided for this application;

[0034] Figure 6 This is the FFT result of Comparative Example 2 of this application;

[0035] Figure 7 The FFT result is shown in Example 2 of this application;

[0036] Figure 8 This is the FFT result of Comparative Example 3 of this application. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0038] Iridescent structural color is a physical color that relies on a micro / nano grating structure. This color is not formed through a chemical reaction of dyes or pigments, but rather due to phenomena such as light interference and diffraction. When white light shines on the surface of the micro / nano structure, different wavelengths of light exhibit different colors at different reflection angles. Therefore, this structural color possesses strong anti-counterfeiting properties. Because the grating structure has an adjustable period, different color effects can be achieved by changing the microstructure of the grating, resulting in highly personalized and difficult-to-counterfeit characteristics, making it particularly suitable for anti-counterfeiting labels, bank cards, and certificates.

[0039] Compared to traditional laser direct writing, laser-induced technology can process more intricate micro- and nano-structures on metal surfaces. The main limitation of laser direct writing lies in the resolution of the grating period, typically unable to achieve sub-micron level precision. Laser-induced technology, however, utilizes the principle of phonon resonance between laser light and metal lattice to induce more refined grating structures. Therefore, laser-induced technology is gradually becoming the preferred method for high-precision anti-counterfeiting iridescent structural color processing. Especially under pulsed lasers in the 1064 nm and 532 nm wavelength bands, grating periods of 1 micrometer or even smaller can be achieved, resulting in structural colors with richer details and stronger anti-counterfeiting effects.

[0040] However, the surface quality of the substrate is crucial for achieving such high-precision laser-induced processing. The cleanliness and smoothness of the surface directly affect the microstructural characteristics of the grating. Improper surface treatment can result in an irregular grating structure after laser processing, failing to achieve the desired iridescent effect and thus failing to meet anti-counterfeiting requirements. For example, if the substrate surface contains dirt, oxides, or other unevenness, the heat and laser energy distribution during the laser induction process will be disrupted, leading to an uneven grating structure.

[0041] In industry, surface treatment typically involves cleaning and processing with highly corrosive acids such as sulfuric acid, hydrochloric acid, and hydrofluoric acid. These strong acids effectively remove oxide layers and impurities from metal surfaces, ensuring a smooth and clean surface and providing better processing conditions for laser-induced processing. Hydrofluoric acid, in particular, is a commonly used chemical reagent for titanium surface treatment, removing oxide layers and providing a smooth surface for subsequent laser-induced processing. However, the fluoride ions in hydrofluoric acid are extremely harmful to humans, capable of damaging bone structure and even causing poisoning. This necessitates extreme caution and appropriate safety precautions when using this chemical in industry. Furthermore, treated titanium metal requires a series of cleaning and drying processes, further increasing the complexity and cost of industrial processing.

[0042] Therefore, ensuring the quality and environmental friendliness of anti-counterfeiting iridescent structural color processing is a pressing technical problem that needs to be solved.

[0043] To address the aforementioned technical problems, according to an embodiment of this application, a composite laser processing method for titanium substrate nano-iridescent anti-counterfeiting structural colors is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0044] This embodiment provides a composite laser processing method for titanium substrate nano-iridescent anti-counterfeiting structural colors. Figure 1 A flowchart of a composite laser processing method for a titanium substrate nano-iridescent anti-counterfeiting structural color provided in this application embodiment is shown below. Figure 1 As shown, the process includes the following steps:

[0045] Step S1: Provide a titanium metal substrate.

[0046] Step S3: A wide-pulse laser light source is used to pre-treat the titanium metal substrate so that a self-flowing layer is formed on the surface of the titanium metal substrate.

[0047] Step S5: Using an ultrafast laser light source, the titanium metal substrate with the self-flowing layer is scanned and processed according to the anti-counterfeiting encryption icon to induce a nano-grating structure with an extractable period, thus obtaining the titanium substrate nano-iridescent anti-counterfeiting structural color.

[0048] Specifically, titanium metal substrates typically use pure titanium or titanium alloy materials. These titanium metal substrates possess high strength, good corrosion resistance, and chemical stability, making them excellent for anti-counterfeiting applications. Laser pretreatment is used to improve surface quality and form specific physical structures. The pretreatment utilizes a wide-pulse laser source. Wide-pulse laser sources have the following characteristics:

[0049] Short-duration giant pulse (SGLP): By emitting a high-power laser pulse within a short period of time, it can produce a stronger localized thermal effect on the material surface compared to a continuous laser source. The laser pulse has a longer width, resulting in a better balance between time and heat input, thus avoiding overheating.

[0050] The thermal ablation time should be moderate: the laser pulse time should be short enough to avoid forming an excessively thick oxide layer on the material surface. An excessively thick oxide layer will not only affect the clarity of the anti-counterfeiting icon, but may also affect the accuracy and functionality of the subsequent grating structure.

[0051] Moderate heat accumulation: Compared to short-pulse lasers, wide-pulse lasers can distribute heat more evenly on the substrate surface, effectively reducing material damage or inhomogeneity caused by heat accumulation. This helps to form a smoother, more uniform self-flowing layer and provides better surface conditions for subsequent laser processing steps.

[0052] After laser pretreatment using a wide-pulse laser source, a self-flowing layer forms on the surface of the titanium metal. This layer facilitates the subsequent formation of the grating structure. The self-flowing layer typically exhibits a micron or nanometer-scale structure, which significantly influences the scattering and refraction characteristics of the laser, thus enhancing anti-counterfeiting effects.

[0053] After forming a self-flowing layer on the surface of a titanium substrate, an ultrafast laser source is used for scanning and processing. Ultrafast lasers have extremely short pulse times (typically in the picosecond or femtosecond range), enabling them to process material surfaces with extremely high precision and speed. Ultrafast lasers can generate extremely high energy densities in a very short time, causing rapid physical changes to occur on the material surface under the laser's influence. This high-precision processing method can induce periodic nanograting structures. Unlike wide-pulse lasers, ultrafast lasers have concentrated energy and extremely short pulse times, thus enabling the precise engraving of fine and uniform grating structures without overheating the substrate or causing thermal damage. The nanograting structure is a periodic, tiny pattern that can generate color effects using the diffraction properties of light. This structure is crucial for anti-counterfeiting labels because it can verify authenticity through specific optical effects (such as iridescent colors). When the laser scans along the anti-counterfeiting encryption icon, it creates a specific nanograting period on the surface, forming a unique color change pattern that can only be observed at specific angles, making counterfeiting difficult.

[0054] This embodiment provides a composite laser processing method for anti-counterfeiting structural colors on a titanium substrate. By employing a wide-pulse laser source and an ultrafast laser source, the processing quality of the anti-counterfeiting iridescent structural colors on the titanium metal substrate surface can be effectively guaranteed. The wide-pulse laser source is used to pre-treat the titanium metal substrate, forming a self-flowing layer to avoid excessive oxidation, thereby ensuring the stability of the surface structure and the accuracy of subsequent processing. Then, the ultrafast laser source scans and processes the titanium metal substrate with the self-flowing layer, precisely inducing a periodic nanograting structure, ensuring the clarity and uniqueness of the iridescent structural colors, and effectively preventing counterfeiting. Furthermore, the energy-saving and environmentally friendly advantages of laser processing are also significant. Laser processing does not require the use of chemicals, reducing waste and by-products, significantly reducing environmental pollution, while improving processing efficiency and reducing energy consumption. Therefore, this embodiment not only ensures high-quality anti-counterfeiting effects but also possesses strong environmental friendliness.

[0055] In one implementation, the roughness of the self-flowing layer is less than or equal to 30 nm.

[0056] Specifically, the smaller the roughness of the self-flowing layer, the more precisely the laser can act on the material surface, reducing the scattering or diffusion of laser energy in unwanted areas and effectively ensuring processing accuracy. If the roughness of the self-flowing layer is large, the laser beam will be interfered with by surface irregularities, resulting in periodic non-uniformity of the nanograting structure, affecting the quality and visual effect of the structure. A surface with a roughness of less than or equal to 30 nm provides a smoother and more consistent medium for laser processing, which helps ultrafast lasers to precisely etch fine nanoscale structures. This allows the anti-counterfeiting iridescent effect to exhibit more vivid and unique color changes under different viewing angles, increasing anti-counterfeiting properties and achieving the best performance of the anti-counterfeiting iridescent effect. Such surface treatment technology can ensure the periodicity of the nanograting and optimize the refraction and interference effects of light, thereby enhancing the anti-counterfeiting effect and preventing counterfeiters from copying or imitating it through other means.

[0057] Furthermore, surfaces with lower roughness typically exhibit less heat accumulation and conduction. During laser processing, heat usually diffuses through the material's surface and is conducted within the titanium substrate. If the surface roughness is high, the heat distribution becomes uneven, potentially leading to localized overheating or material damage, and even affecting the stability of the nanograting structure. Therefore, a self-flowing layer roughness of 30 nm or less signifies a smoother surface, allowing for more uniform heat distribution, reducing the risk of localized overheating or deformation, and thus improving processing stability and quality.

[0058] This embodiment significantly improves the processing quality and environmental friendliness of the anti-counterfeiting iridescent structural color by controlling the roughness of the self-flowing layer to below 30 nm. First, lower surface roughness ensures the precise generation of the grating structure during laser processing, thereby improving the stability and vividness of the iridescent color and increasing the difficulty of anti-counterfeiting. Second, a smooth surface reduces light scattering, ensuring a more durable anti-counterfeiting effect, and enhancing corrosion and oxidation resistance, making the structural color less prone to fading over long-term use. Furthermore, lower roughness makes laser processing more efficient, reducing energy waste and waste generation, thus reducing environmental impact and dependence on chemicals, further improving the environmental friendliness of the processing process.

[0059] In one implementation, the wide-pulse-width laser source uses a pulse width of 2-120 ns.

[0060] Specifically, the pulse width of a laser refers to the duration of the laser output signal, which determines the energy, thermal effect, and interaction with the material during each pulse emission. With a short pulse width (2-20 ns), the laser pulse duration is short, and the peak power is high, rapidly heating the surface of a titanium substrate to a molten state. This short-pulse laser source primarily heats the material locally, suitable for forming fine, micro-molten pools. In this case, the surface of the titanium substrate rapidly melts and flows within a short time, forming a self-flowing layer, which is typically thin and has a relatively clear edge. With a longer pulse width (40-120 ns), the laser can continuously apply energy to the surface of the titanium substrate, producing a longer heating effect. A longer pulse width means a longer duration of laser pulse influence on the titanium substrate, leading to a stronger heat accumulation effect and thus forming a deeper and wider molten pool. This helps to generate a thicker self-flowing layer and makes the material within the molten pool more fluid, allowing for better expansion and redistribution, resulting in a uniform surface treatment effect.

[0061] This embodiment employs a wide-pulse laser source with a pulse width of 2-120ns, which can improve environmental friendliness while ensuring the processing quality of the anti-counterfeiting iridescent structural color. By precisely controlling the laser pulse width, shorter pulses (2-20ns) have higher peak power, enabling rapid heating of the material surface and precise formation of microstructures in a shorter time. This helps avoid excessive heat transfer, ensuring the precision and surface quality of laser processing. Longer pulses (40-120ns), on the other hand, allow for a longer heating time, enabling more uniform heating of the material surface and forming a self-flowing layer, which contributes to the optimization of surface morphology.

[0062] In one embodiment, the scanning interval of a wide-pulse laser source or an ultrafast laser source is less than or equal to the spot diameter.

[0063] Specifically, the spot diameter refers to the diameter of the laser beam at the focal point, that is, the size of the focused laser beam. A smaller spot diameter can provide higher spatial resolution, while a larger spot diameter helps to increase the coverage area of ​​the laser beam. The scanning interval refers to the distance between two adjacent laser beam irradiations during the scanning process. In this embodiment, the scanning interval is less than or equal to the spot diameter, meaning that the laser scanning path covers a smaller area, which may result in some overlap between the areas irradiated by each laser beam. When the scanning interval is less than the spot diameter, the energy of a wide-pulse-width laser source or an ultrafast laser source can be concentrated in the overlapping area, which helps to increase the laser energy density at each point, making it suitable for high-precision processing or detailed processing. If the scanning interval is equal to the spot diameter, there will be minimal overlap between the laser beams, ensuring uniform coverage of the scanning path without wasting excess energy.

[0064] This embodiment significantly improves the processing quality of the anti-counterfeiting iridescent structural colors by employing a wide-pulse-width laser source or an ultrafast laser source and designing the scanning interval to be less than or equal to the spot diameter. The smaller scanning interval ensures higher laser processing precision, avoiding color unevenness and structural distortion caused by excessively large spot spacing, thus guaranteeing the clarity and stability of the anti-counterfeiting effect. Furthermore, this processing method reduces thermal effects, minimizing material thermal damage and energy waste, contributing to environmental protection goals while reducing material waste and improving processing efficiency. Through a high-precision, low-energy processing procedure, not only is the anti-counterfeiting capability of the anti-counterfeiting label enhanced, but its wear resistance and long-term stability are also improved.

[0065] In one embodiment, when the wide-pulse laser source adopts the MOPA laser source, the laser output power of the wide-pulse laser source is 20-90W, the repetition frequency is 2600kHz, and the scanning speed is 7000-14000mm / s.

[0066] Specifically, the MOPA laser source has an output power of 20-90W, enabling laser processing to adapt to various materials and processing depths. Lower power can be used for fine marking and microstructural processing on material surfaces, while higher power is suitable for generating more complex structural colors or rapid processing of larger surface areas. Precise control of the output power avoids overheating and material damage, ensuring the quality of the anti-counterfeiting iridescent structural color processing. The power adjustment characteristics of the MOPA laser source effectively control the heat-affected zone during processing, preventing excessive heat input from damaging surrounding materials, thereby reducing thermal deformation and focus drift. This is crucial for the quality of the anti-counterfeiting iridescent structural color, especially in high-precision processing, where maintaining a small heat-affected zone effectively ensures the uniformity and clarity of the structural color.

[0067] A repetition frequency of 2600kHz means that the laser source can emit multiple pulses per unit time. When the laser pulses repeat at a high frequency, each pulse generates a new pulse effect on the molten pool formed by the previous pulse, which can maintain the stable flow of the self-flowing layer, thereby avoiding localized overcooling or overheating and ensuring the uniformity of the self-flowing layer. In addition, high-frequency laser pulses can also cause the material to melt and cool repeatedly in a very short time. This rapid pulse effect helps the material to melt uniformly and generate finer microstructures. Especially in complex anti-counterfeiting iridescent structures, a high repetition frequency can effectively control the details of the microstructures, making them clearer and more stable.

[0068] A scanning speed of 7000-14000 mm / s means that laser processing is very fast, which helps to improve production efficiency. High scanning speeds are particularly suitable for large-scale production of anti-counterfeiting iridescent structural colors, completing the processing of large areas in a short time. Despite the high scanning speed, the advantage of the MOPA laser source lies in its ability to maintain temperature control of the processed surface by appropriately adjusting the pulse width and output power, avoiding overheating and scorching. By matching the scanning speed with appropriate power and frequency, the MOPA laser source can maintain the temperature stability of the processed surface at high speeds, allowing the molten material to form a uniform flow layer along the scanning path, ultimately forming a precise self-flowing layer after cooling.

[0069] This embodiment utilizes a MOPA laser light source, achieving precise laser control under conditions of 20-90W laser output power, 2600kHz repetition rate, and 7000-14000mm / s scanning speed. This ensures high quality and environmental friendliness in the processing of anti-counterfeiting iridescent structural colors. Precise adjustment of laser power prevents overheating or scorching during processing, guaranteeing the uniformity and clarity of the structural colors. High repetition rate and high-speed scanning ensure improved processing efficiency while reducing energy waste and thermal effects, thus increasing production efficiency. Compared to traditional chemical anti-counterfeiting technologies, laser processing eliminates the need for chemical substances, avoiding the emission of hazardous waste and resulting in a lower environmental impact. This efficient and environmentally friendly laser processing technology not only improves the quality and stability of anti-counterfeiting labels but also ensures the sustainability of the production process.

[0070] In one implementation, when the wide-pulse-width laser source is a GHz femtosecond laser source in Burst mode, the laser output power of the wide-pulse-width laser source is 15W, the scanning speed is 1800-12000mm / s, the repetition frequency is 500kHz, and the pulse width of a pulse train is 120ns in Burst mode.

[0071] Specifically, at an output power of 15W, the laser energy is high enough to heat the material surface to a sufficient temperature in a short time, causing thermal effects such as melting or evaporation to form the desired microstructure. The high power allows the laser to rapidly transfer heat, stimulating a quick response in the material, which is particularly effective for materials with high surface roughness or those that are difficult to process. During the formation of the self-flowing layer, the thermal energy provided by the laser pulse melts the material surface and creates flow through surface tension, thereby optimizing the surface morphology. The 15W power ensures sufficient heat accumulation during this process, allowing the surface material enough time to flow and form the desired self-flowing layer.

[0072] In the formation of a self-flowing layer, excessively high scanning speeds result in too short a residence time of the laser beam in each region, which may be insufficient to melt or flow the material surface, thus failing to form an ideal self-flowing layer. Conversely, excessively low scanning speeds may lead to excessive heat accumulation, easily causing surface ablation or morphological instability. Therefore, a scanning speed of 1800-12000 mm / s optimizes the residence time for thermal effects, ensuring that the material surface can be uniformly heated under laser scanning, forming a stable self-flowing layer.

[0073] Repetition rate refers to the frequency at which laser pulses are emitted. A repetition rate of 500 kHz means that the laser emits 500,000 pulses per second. At this frequency, the interval between laser pulses is extremely short. This allows the laser beam to continuously act on the surface of the titanium substrate during processing, generating a periodic thermal effect that effectively promotes the heating and melting of the surface material. At a higher repetition rate, the time interval between each pulse is short enough that the surface of the titanium substrate can be kept at a temperature close to its melting point through thermal accumulation, thus facilitating the formation of a self-flowing layer. Through multiple short pulses, the laser can more precisely control the surface temperature, avoiding overheating and ensuring the formation of a uniform self-flowing layer.

[0074] Burst mode means that the laser is output in the form of a pulse train, with each pulse train containing multiple pulses. A pulse train with a pulse width of 120 ns typically has a high energy density, capable of transferring a large amount of energy to the surface of a titanium substrate in a short time. The advantage of this mode is that it can increase the local temperature and accelerate the heating rate of the titanium substrate surface through the superposition of multiple pulses, thereby achieving rapid self-flow layer formation. Because the laser pulse train provides high energy in a short time, the surface of the titanium substrate can heat up rapidly, and the molten area flows rapidly, forming the ideal self-flow layer effect. In Burst mode, the energy density of the laser source is concentrated, thereby generating sufficient thermal effect on the surface to support the formation of the self-flow layer.

[0075] This embodiment employs a GHz femtosecond laser source in Burst mode, combined with an output power of 15W, a scanning speed of 1800-12000 mm / s, a repetition frequency of 500 kHz, and a pulse width of 120 ns. This allows for precise control of heat accumulation and thermal diffusion effects, promoting uniform melting and flow on the surface of the titanium substrate to form the desired self-flowing layer. This laser processing method not only improves processing accuracy and speed but also optimizes surface quality, ensuring environmental friendliness while meeting the needs of precision processing such as anti-counterfeiting and microstructure applications.

[0076] In one embodiment, the ultrafast laser source is a picosecond laser source or a femtosecond laser source; wherein, when the ultrafast laser source is a picosecond laser source, the control current of the ultrafast laser source is 2.1-3.2A, the repetition frequency is 20-30kHz, and the scanning speed is 5-400mm / s.

[0077] Specifically, control current is a crucial performance indicator of a laser source, representing the amount of current consumed during operation. For picosecond laser sources, a control current between 2.1A and 3.2A indicates that the laser's power, operating within this range, provides sufficient energy to induce the desired thermal effects. Higher laser control currents result in stronger laser pulses, generating enough heat to form nanograting structures on the titanium substrate surface. High current allows for the release of a large amount of energy in a very short time, enhancing the melting and evaporation processes on the material surface. This rapid thermal action facilitates the formation of surface microstructures and effectively prevents thermal damage.

[0078] Scanning speed refers to the speed at which the laser beam moves across the titanium surface, ranging from 5 to 400 mm / s. Within this speed range, the duration of laser contact is directly related to surface temperature control. At low scanning speeds (e.g., 5 mm / s), the laser beam remains in each region for a longer time, allowing sufficient time for the material surface to absorb heat, thus enabling the formation of deeper and finer nanostructures. At high scanning speeds (e.g., 400 mm / s), the laser's dwell time on the material surface is shorter, resulting in faster heat transfer and shallower nanostructures. This is suitable for applications requiring rapid processing but with lower surface precision requirements.

[0079] This embodiment employs a picosecond laser light source for processing anti-counterfeiting iridescent structural colors, achieving high-precision and high-quality processing results. By adjusting the laser control current within the range of 2.1A to 3.2A and the scanning speed between 5-400mm / s, the energy of the laser pulse and the processing speed can be precisely controlled, thereby forming a micro-grating structure on the metal surface. Due to the short duration of the picosecond laser pulse, heat diffusion is effectively controlled, avoiding excessive heat-affected zones and ensuring the high precision and stability of the iridescent structure. This precise processing not only improves the anti-counterfeiting effect but also ensures the uniformity and visual appeal of the structural colors. Furthermore, the laser processing generates less heat, reducing exhaust emissions and material waste, thus exhibiting high environmental friendliness. Therefore, this technology ensures high-quality processing of anti-counterfeiting iridescent structural colors while achieving energy efficiency and environmental friendliness, meeting the requirements of green environmental protection.

[0080] In one embodiment, the scanning speed is 5-10 mm / s when the control current of the ultrafast laser source is 2.1-2.5A; and the scanning speed is 200-400 mm / s when the control current of the ultrafast laser source is 2.8-3.2A.

[0081] Specifically, with a control current of 2.1-2.5A for the ultrafast laser source and a scanning speed of 5-10mm / s, the laser scans the material surface at a relatively low speed. At this speed, the laser energy output is low, and the scanning speed is slow, which facilitates more precise and in-depth processing. Due to the slower scanning speed, each laser pulse has a longer duration of contact with the titanium surface, allowing the laser energy to act more fully on the material surface, forming a finer and more uniform microstructure. The slow scanning speed ensures the structural accuracy of each laser-affected area, avoiding uneven textures or distortions. Therefore, when processing anti-counterfeiting iridescent structures, it maximizes the clarity and stability of the visual effect.

[0082] Furthermore, the lower control current (2.1-2.5A) allows for precise control of the laser's energy output, reducing the thermal impact on materials and minimizing thermal damage or deformation to the material surface. This ensures a more uniform and durable iridescent structure. In this context, the short-pulse characteristics of the ultrafast laser source effectively reduce heat diffusion, resulting in a finer and clearer processed surface and a more pronounced anti-counterfeiting effect.

[0083] When the control current of the ultrafast laser source increases to 2.8 - 3.2 A, the scanning speed increases to 200 - 400 mm / s. At this time, the energy output of the laser pulse increases, and at the same time, the scanning speed speeds up, which means that the action time of each laser beam is shortened, and the area of laser action increases. The combination of high current and high-speed scanning is suitable for scenarios of large-area and high-efficiency processing. Due to the increase in the output of laser energy, within a short action time, the laser can generate a large amount of heat, quickly evaporating the tiny parts on the surface of the material, forming a relatively rough or deep texture structure. This processing method can quickly and efficiently process a large range of surfaces, and is suitable for anti-counterfeiting designs that require a large processing area and a large structural depth.

[0084] In this embodiment, a lower current of 2.1 - 2.5 A is combined with a low scanning speed of 5 - 10 mm / s, which is mainly suitable for processing tasks with extremely high precision requirements and can ensure the fineness and uniformity of microstructures; while a higher current of 2.8 - 3.2 A is combined with a high-speed scanning of 200 - 400 mm / s, which is suitable for efficient and rapid anti-counterfeiting iridescent color processing of larger areas or deeper structures. While ensuring the processing efficiency, it can still control the thermal influence and material damage. The settings of these two groups of different parameters can be flexibly adjusted according to actual needs to achieve different processing effects.

[0085] Example 1

[0086] Step 1: Design an iridescent anti-counterfeiting icon in the shape of "Qilin" to provide a pattern template for subsequent laser processing.

[0087] Step 2: Load the designed "Qilin" - shaped iridescent anti-counterfeiting icon into the control software of the Golden Orange laser system and prepare it for laser processing.

[0088] Step 3: Place the unpolished titanium metal substrate in the laser processing system, and select the JPT infrared MOPA laser source with a laser output power of 100 W. Through the Golden Orange control software, adjust the laser output power to 60 W, the repetition frequency to 2600 kHz, the scanning speed to 7000 mm / s, the pulse width to 4 ns, and the scanning interval to 40 μm.

[0089] Step 4: Replace the laser source with an ultrafast laser source (Kepler 10 W infrared picosecond laser), and adjust the picosecond laser control current to 2.2 A, the repetition frequency to 20 kHz, the scanning speed to 8 mm / s, and the scanning interval to 35 μm through the Golden Orange control software.

[0090] The surface roughness of the self-flow layer was measured non-contactly using a white light interferometer (Bruker Contour GT-K, vertical resolution 0.1 nm), with a 50× objective lens and a field of view of 0.9 mm × 0.7 mm. Sa (arithmetic mean height) was extracted according to ISO 25178-2. The pretreated titanium surface had Sa=28, which meets the consistency requirements of subsequent LIPSS cycles.

[0091] Comparative Example 1

[0092] Similar to Example 1, the only difference is that Comparative Example 1 did not perform a polishing pretreatment on the titanium metal substrate, i.e., it did not have step three.

[0093] Both Example 1 and Comparative Example 1 were photographed under the same shooting conditions, and the results were as follows: Figure 2 The comparison diagram shown shows that, Figure 2 (a) shows the result of photographing Example 1. Because the titanium substrate was not pre-treated, gray spots appear, leading to a decrease in reflectivity. Furthermore, there are many burrs at the edges of the image, resulting in an overall "hazy" appearance to the human eye. Compared to... Figure 2 (b) is the result of the photo taken in Example 1. The titanium metal substrate was pretreated to form a self-flowing layer that filled the scratch area, improved the reflectivity, and the color saturation was fuller than that of Comparative Example 1. The brightness was uniform and the image was clear.

[0094] Figure 3 The FFT result is for Comparative Example 1. Figure 3 (a) in the figure is the nanograting of Comparative Example 1. Figure 3 In (b), the wave vector after Fourier transform is extracted from the nanograting. Only the central DC bright spot is visible, and there are no symmetrical satellite peaks. The wave vector k cannot be defined, so there is no extractable period, and the anti-counterfeiting capability of "parameter-period mapping" is lost. Figure 4 The FFT result is from Example 1. Figure 4 (a) in the figure represents the nanograting of Example 1. Figure 4 (b) shows the wave vector after Fourier transform of the nanograting, where a pair of symmetrical satellite peaks can be seen in the same field of view. Figure 4 (c) shows the analysis of the symmetric satellite peaks, with k=1.147µm along the principal direction of LIPSS. -1 The period T = 1 / k = 872 nm, meeting the anti-counterfeiting requirement of "extractable period". For example, a database of "laser output power - scanning speed - period" can be established, with each 0.02 J / cm² period... -2 ×100mm s -1 One grid enables digital key-level anti-counterfeiting (the decoding end only requires a mobile phone photo + 2D-FFT peak reading).

[0095] Example 2

[0096] Step 1: Design an iridescent anti-counterfeiting icon in the shape of "Kirin" to provide a pattern template for subsequent laser processing.

[0097] Step 2: Load the designed iridescent anti-counterfeiting icon in the shape of "Kirin" into the control software of the Golden Orange laser system and prepare for laser processing.

[0098] Step 3: Place the unpolished titanium metal substrate in the laser processing system and select a GHz femtosecond laser source in Burst mode. Through the Golden Orange control software, adjust the laser output power to 15 W, the repetition frequency to 500 kHz, the scanning speed to 10000 mm / s, the pulse width to 10 ns. In Burst mode, the pulse width of a pulse train is 120 ns, and the scanning interval is adjusted to 80 μm.

[0099] Step 4: Replace the laser source with an ultrafast laser source (Kaplin 10 W infrared picosecond laser), and adjust the picosecond laser control current to 3 A through the Golden Orange control software, the repetition frequency to 25 kHz, the scanning speed to 200 mm / s, and the scanning interval to 35 μm.

[0100] The surface roughness of the self-leveling layer is measured non-contact using a white light interferometer (Bruker Contour GT-K, vertical resolution 0.1 nm), with an objective lens of 50× and a field of view of 0.9 mm × 0.7 mm. Sa (arithmetic mean height) is extracted according to ISO 25178-2; the Sa of the pre-treated titanium surface is 25, meeting the requirements for the subsequent LIPSS period consistency.

[0101] Comparative Example 2

[0102] Same as Example 2, except that in Comparative Example 2, the titanium metal substrate was not polished pretreated, that is, there was no Step 3.

[0103] Comparative Example 3

[0104] Same as Example 2, except that in Comparative Example 3, the titanium metal substrate was pretreated with 10% hydrochloric acid.

[0105] Examples 2 and Comparative Example 2 were photographed under the same shooting conditions, and the comparison graph shown in Figure 5 was obtained. Among them, Figure 5 in (a) is the result of photographing Comparative Example 2. Since the titanium metal substrate was not pretreated, gray spots would appear, resulting in a decrease in reflectivity. Secondly, there were more burrs on the graphic edge. Therefore, the overall human eye perception was "gray and hazy". Compared with Figure 5 in (b) is the result of photographing Example 2. After the titanium metal substrate was pretreated, the formed self-leveling layer filled the scratched area, the reflectivity increased, the color saturation was more saturated than that of Comparative Example 2, and the brightness was uniform and the image was clear.

[0106] Figure 6 The FFT results are for Comparative Example 2. Figure 6 (a) in the figure is the nanograting of Comparative Example 2. Figure 6 In (b), the wave vector after Fourier transform is extracted from the nanograting. Only the central DC bright spot is visible, and there are no symmetrical satellite peaks. The wave vector k cannot be defined, so there is no extractable period, and the anti-counterfeiting capability of "parameter-period mapping" is lost. Figure 7 The FFT result is shown in Example 2. Figure 7 (a) in the figure represents the nanograting of Example 2. Figure 7 (b) shows the wave vector after Fourier transform of the nanograting, where a pair of symmetrical satellite peaks can be seen in the same field of view. Figure 7 (c) shows the analysis of the symmetric satellite peaks, with k=1.027µm along the principal direction of LIPSS. -1 The period T=1 / k=973nm meets the anti-counterfeiting requirement of "extractable period".

[0107] Please see Figure 8 The FFT results are for Comparative Example 3. Figure 8 (a) in the figure is the nanograting of Comparative Example 3. Figure 8 (b) in the figure represents the wave vector after Fourier transform extraction of the nanograting. Figure 8 (c) in the figure represents the analysis of symmetrical satellite peaks, since Cl - It penetrates the surface and resides at the grain boundary. During laser ablation, the local plasma density increases sharply, causing LIPSS periodic instability and ridge line breakage. The FFT satellite peak degenerates into discrete cloud spots, making it impossible to provide a reliable wave vector.

[0108] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0109] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0110] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

[0111] Although embodiments of this application have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of this application, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A composite laser processing method of a titanium substrate nano-holographic anti-counterfeiting structural color, characterized in that, The method comprises: providing a titanium metal substrate; preprocessing the titanium metal substrate with a wide pulse width laser source to form a self-flow layer with a roughness of less than or equal to 30 nm on the surface of the titanium metal substrate, the self-flow layer being used to fill in the scratch area of the surface; the wide pulse width laser source uses a pulse width of 2-120 ns; scanning and processing on the titanium metal substrate with a self-flow layer according to a security encryption icon with an ultrafast laser source to induce a nanograting structure with an extractable grating period of 872 nm or 973 nm, obtaining a titanium substrate nanoholographic security color.

2. The method of claim 1, wherein, The scanning interval of the wide pulse width laser source or the ultrafast laser source is less than or equal to the spot diameter.

3. The method of claim 1, wherein, When the wide pulse width laser source is a MOPA laser source, the laser output power of the wide pulse width laser source is 20-90 W, the repetition frequency is 2600 kHz, and the scanning speed is 7000-14000 mm / s.

4. The method of claim 1, wherein, When the wide pulse width laser source is a GHz femtosecond laser source in Burst mode, the laser output power of the wide pulse width laser source is 15 W, the scanning speed is 1800-12000 mm / s, and the repetition frequency is 500 kHz. In Burst mode, the pulse width of one pulse train is 120 ns.

5. The method of claim 1, wherein, The ultrafast laser source uses a picosecond laser source or a femtosecond laser source; when the ultrafast laser source uses the picosecond laser source, the control current of the ultrafast laser source is 2.1-3.2 A, the repetition frequency is 20-30 kHz, and the scanning speed is 5-400 mm / s.

6. The method of claim 4, wherein, when the control current of the ultrafast laser source is 2.1-2.5 A, the scanning speed is 5-10 mm / s; when the control current of the ultrafast laser source is 2.8-3.2 A, the scanning speed is 200-400 mm / s.

7. A titanium substrate nano-iridescent anti-counterfeiting structural color, characterized in that, The titanium substrate nanoholographic security color is prepared by the composite laser processing method of any one of claims 1-6.

8. Use of a titanium substrate nanoholographic security structure color, characterized in that, The grating period of the nanograting structure in the titanium substrate nanoholographic security color prepared by the method of any one of claims 1-6 or the titanium substrate nanoholographic security color of claim 7 is extracted, and a laser parameter-period mapping database is established for security verification.

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