Apparatus and method for removing ink from a surface of a transparent material using a laser

Abstract

The application discloses a device and method for removing ink on the surface of transparent material by using laser, and relates to the technical field of laser processing.The device comprises a laser, a beam expander, a phase modulation component, a scanning galvanometer, a scanning lens and a mirror, a laser beam is turned by the mirror to be emitted to the ink layer at a preset oblique angle relative to the normal of the product surface after being expanded, polarized modulated, deflected by the galvanometer and focused by the scanning lens.The method comprises providing a product to be processed, modulating the polarization direction of the laser beam and making it incident to the ink layer at an oblique angle to remove by ablation.The application utilizes the oblique laser beam with a specific polarization direction to generate thermal deposition and thermal stress coupling in the residual film, destroys and vaporizes the film, and eliminates the pattern distortion caused by oblique incidence by trajectory correction compensation, realizes complete removal of the residual film without damaging the transparent substrate, and the processing pattern contour is accurate.

Description

Technical Field

[0001] This invention relates to the field of laser processing technology, and in particular to an apparatus and method for removing ink from the surface of transparent materials using a laser. Background Technology

[0002] Ink-printed products are widely used in the 3C industry, such as mobile phone casings, laptop keyboards, and touchscreen components. After printing, products may require the removal of ink from areas that do not need to be covered due to design requirements, process needs, or ink overflow. This allows the product to achieve the desired light transmission while effectively blocking stray light from entering areas that should not be transparent.

[0003] Currently, there are existing technical solutions for removing ink from the surface of transparent materials using lasers. For example, Chinese patent CN201810088426.5 discloses a method for creating openings in the ink layer of a glass cover plate. An ink layer is applied to a transparent glass cover plate. The ink layer is positioned directly opposite the laser's output port, and the laser processes the ink layer. The line scanning path follows the edge contour of the target opening shape, forming an annular isolation zone. The glass cover plate is then flipped, and a surface scan is performed on the glass surface to remove the ink area within the annular isolation zone. This solution employs a two-sided processing method, using low power and defocusing during surface scanning to ensure the transmittance of the glass cover plate.

[0004] For example, Chinese patent CN201610348063.5 discloses a method for processing windows using lasers. After spraying an ink layer onto the window processing area on the surface to be processed of the workpiece, the ink layer is removed from the opposite side of the workpiece with the ink layer by a laser machine using a defocusing processing method.

[0005] For example, Chinese patent CN106739589A discloses a printing process in which ink is printed on a translucent substrate to form an ink layer. Then, an infrared picosecond laser is used to roughly scan and remove the ink in a preset area, and then a fine scan is used to remove the residual ink. The ink removal process is divided into a rough scan and a fine scan.

[0006] However, the aforementioned existing technical solutions have significant technical flaws in practical use. For ink products with transparent materials such as glass and sapphire as the base, during the laser removal process, once the ink reaches a certain thickness, the laser will penetrate the material. This is because ink is mainly composed of organic components, which become transparent when ablated to a sufficiently thin layer. At this point, the absorption rate of the laser drops sharply, resulting in a seemingly complete removal process, but in reality, a thin film still adheres to the material surface and does not easily detach, requiring the use of thinner or alcohol with appropriate pressure to wipe it off. Furthermore, during the high-temperature curing process, a layer of cured adhesive may form at the interface between the ink and glass. This cured adhesive is transparent and has a high transmittance to the laser. This film does not remain after every processing; it is only more likely to fail to be completely removed by laser when the total ink thickness is not an integer multiple of the amount removed in a single operation. If the laser power is further increased to target the residual film, it may damage the sapphire or glass surface. In situations requiring high-precision inspection in the viewing area, this transparent film can be observed by the human eye under strong light or a microscope. In severe cases, moiré patterns may form between the transparent film and the base material, seriously affecting product quality.

[0007] Therefore, how to completely remove the transparent film remaining after laser processing without damaging the transparent material substrate is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides an apparatus and method for removing ink from the surface of transparent materials using a laser, solving the problems mentioned in the background section. This invention uses a reflector to direct the laser beam at a preset tilt angle and utilizes a phase modulation element to modulate the polarization direction of the laser beam. This causes the tilted laser beam with a specific polarization direction to generate thermal deposition and thermal stress coupling within the ink layer, completely destroying and vaporizing the residual film. This solves the technical problem of thoroughly removing transparent film residue without damaging the substrate. Simultaneously, by real-time correction and compensation of the preset processing trajectory, the graphic distortion caused by the tilted incident light is eliminated, achieving the beneficial effects of accurate graphic contours and high processing quality.

[0009] An apparatus for removing ink from the surface of a transparent material using a laser includes a laser, a beam expander, a phase modulation element, a scanning galvanometer, a scanning lens, and a reflector. The laser emits a laser beam. The beam expander is disposed in the emission path of the laser to expand the laser beam. The phase modulation element is located in the emission path of the beam expander to modulate the polarization direction of the laser beam. The scanning galvanometer is disposed in the emission path of the phase modulation element to deflect the laser beam so that the laser beam scans along a preset processing trajectory. The scanning lens is disposed in the emission path of the scanning galvanometer to focus the laser beam. The reflector is disposed in the emission path of the scanning lens to deflect the laser beam at a preset angle relative to the normal of the surface of the product to be processed.

[0010] Preferably, the tilt angle is the angle α between the deflected laser beam and the normal to the surface of the product to be processed, which is 12°-25°.

[0011] Preferably, the installation angle θ of the reflector is the angle between the axis of the reflector and the emitted laser beam of the scanning lens, and the installation angle θ of the reflector satisfies θ = 45° - α / 2.

[0012] Preferably, the installation angle θ of the reflector is 32.5°-39°.

[0013] Preferably, the laser and the beam expander are coaxially arranged, the phase modulation element is placed horizontally with its surface normal parallel to the axes of the beam expander and the laser, the axis of the scanning galvanometer is perpendicular to the axis of the beam expander, and the axis of the scanning lens is coaxial with the axis of the scanning galvanometer.

[0014] Preferably, the phase modulation element is a half-wave plate, and the scanning galvanometer has an X-axis lens and a Y-axis lens.

[0015] A method for removing ink from the surface of a transparent material using a laser, based on the apparatus for removing ink from the surface of a transparent material using a laser as described in any of the preceding claims, includes the following steps: S1. Provide a product to be processed, wherein the product to be processed is a transparent material product and the surface is covered with an ink layer; S2. A laser beam is provided by a laser, the laser beam is expanded by the laser beam, and then the polarization direction of the expanded laser beam is modulated by a phase modulation device. Then, a scanning galvanometer is used to drive the modulated laser beam to deflect, so that the laser beam scans along a preset processing trajectory. Finally, the deflected laser beam is focused by a scanning lens, so that the polarization direction of the laser beam has a preset polarization deflection angle relative to the surface of the product to be processed. S3. The focused laser beam is deflected by the reflector, so that the laser beam is emitted at a preset angle relative to the surface normal of the product to be processed and onto the ink layer on the surface of the product to be processed, thereby ablation and removal of the ink layer on the product to be processed.

[0016] Preferably, in step S2, the phase modulation device modulates the polarization direction of the laser beam so that the modulated polarization direction forms an angle of 12°-25° with the surface normal of the product to be processed.

[0017] Preferably, in step S2, after the laser beam is provided by the laser, the laser beam is expanded by a beam expander, its polarization direction is modulated by a phase modulation element, it is deflected by a scanning galvanometer, and it is focused by a scanning lens before being emitted to the reflecting mirror.

[0018] Preferably, in step S3, after the reflector deflects the laser beam, it performs real-time correction and compensation on the preset processing trajectory according to the preset tilt angle, so that the actual processing contour formed by the laser beam scanning on the ink layer is consistent with the preset pattern.

[0019] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention uses a reflector to deflect the focused laser beam at a preset angle relative to the surface normal of the product to be processed. Simultaneously, a phase modulation element modulates the polarization direction of the laser beam, causing it to strike the ink layer surface at an angle. Because the laser beam enters the ink layer at an angle, it forms a conical focused beam inside the film. The film absorbs the laser energy, resulting in thermal deposition and increased internal temperature rise. This thermal stress coupling process causes structural damage to the film. The damaged film is more easily ablated and vaporized by the laser. Thus, without increasing the laser power, the ink layer and residual film are completely removed. This solves the technical problems in existing technologies where a sudden drop in ink absorption or interface curing adhesive leads to transparent film residue, while increasing the power damages the transparent material substrate. The invention achieves the technical effect of completely removing residual film while protecting the transparent material substrate. 2. This invention limits the tilt angle α of the laser beam relative to the normal of the product surface to 12°-25°. When the laser beam is incident within this angle range, it can generate the best thermal deposition effect and thermal stress coupling effect inside the residual film. This ensures that the film is fully destroyed and easily vaporized, while avoiding the serious spot distortion or insufficient energy density caused by excessive angle, which would affect the removal effect. This solves the technical problem of incomplete removal or low processing efficiency caused by improper selection of tilt angle, and achieves the technical effect of ensuring removal effect while taking into account processing efficiency. 3. This invention sets the installation angle θ of the reflector to satisfy θ=45°-α / 2, and further limits it to 32.5°-39°, so that the reflector can accurately deflect the horizontally transmitted focused laser beam into an outgoing beam with a preset tilt angle relative to the normal of the product surface. Through precise calculation of the plane mirror rotation formula, the laser beam is ensured to be incident on the product surface at the desired tilt angle. This solves the technical problem of how to achieve precise tilting of the laser beam in a compact optical path, and achieves the technical effect of simple optical path structure and precise angle control. 4. This invention achieves a compact optical path system layout and accurate optical axis alignment by coaxially arranging the laser and beam expander, horizontally placing the phase modulation element with its surface normal parallel to the axes of the beam expander and laser, arranging the axis of the scanning galvanometer perpendicular to the axis of the beam expander, and arranging the axis of the scanning lens coaxial with the axis of the scanning galvanometer. This ensures that the energy loss of the laser beam is minimized during transmission, solves the technical problem of beam quality degradation or optical path debugging difficulties caused by unreasonable positional relationships of various optical path components, and achieves the technical effects of high optical path stability and high beam transmission efficiency. 5. This invention uses a half-wave plate as a phase modulation element. By rotating the half-wave plate around its central axis, the polarization direction of linearly polarized light can be continuously changed, making the adjustment of the polarization direction more flexible, precise and convenient. It solves the technical problem of how to achieve precise control of the polarization direction of a laser beam in a simple way, and achieves the technical effect of simple operation and high control accuracy in polarization direction adjustment. 6. By setting X-axis and Y-axis lenses in the scanning galvanometer, the present invention realizes high-speed and precise scanning of the laser beam along a preset processing trajectory in a two-dimensional plane. Combined with the focusing effect of the scanning lens, the laser beam can accurately remove the ink layer along any preset graphic trajectory, solving the technical problem of difficult precise control of the processing trajectory of complex contour graphics, and achieving the technical effect of high processing graphics accuracy and wide applicability. 7. In step S2, the present invention ensures that the laser beam is processed in the optimal order in each functional module by first expanding the beam with a beam expander, then modulating the polarization direction with a phase modulation element, then deflecting and scanning with a scanning galvanometer, and finally focusing and outputting the beam. This solves the technical problem of reduced processing quality caused by unreasonable optical path processing order and achieves the technical effect of clear process flow and coordinated cooperation among all links. 8. In step S3, the present invention, after the laser beam is deflected by a reflector, performs real-time correction and compensation on the preset processing trajectory according to a preset tilt angle, so that the actual processing contour formed by the laser beam scanning on the ink layer is consistent with the preset pattern. Since the projection position of the laser spot on the scanning plane will produce geometric distortion when the laser beam is incident on the product surface at an tilt angle, the pattern deviation caused by the tilted incident is eliminated by pre-processing the processing trajectory through coordinate transformation and correction compensation. This solves the technical problem of distorted processing contours leading to substandard product dimensional accuracy under tilted incident conditions, achieving the technical effect of accurate pattern contours and high product processing precision during tilted processing. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of the device for removing ink from the surface of transparent materials using a laser, as per the present invention. In the diagram: 1. Laser; 2. Beam expander; 3. Phase modulation element; 4. Scanning galvanometer; 5. Scanning lens; 6. Mirror. Detailed Implementation

[0021] To enable those skilled in the art to better understand the technical solution of the present invention, the product of the present invention will be further described in detail below with reference to embodiments and accompanying drawings.

[0022] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly attached to the other element or there may be an intervening element; when an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation. Example

[0023] like Figure 1 As shown, the present invention provides an apparatus for removing ink from the surface of a transparent material using a laser, comprising a laser 1, a beam expander 2, a phase modulation element 3, a scanning galvanometer 4, a scanning lens 5, and a reflector 6; the laser 1 is used to emit a laser beam, which can be a commonly used solid-state laser, gas laser, or fiber laser, preferably a picosecond laser or femtosecond laser, whose output laser beam has a high peak power and a short pulse width, enabling instantaneous ablation removal of the ink material and reducing damage to the transparent material substrate by the heat-affected zone. The laser beam emitted by the laser 1 is usually linearly polarized light, but its polarization direction is random.

[0024] The beam expander 2 is disposed in the output optical path of the laser 1 to expand the laser beam. The laser beam emitted by the laser 1 is usually small in diameter and has a large divergence angle. The quality of the spot after direct focusing is not good. The beam expander 2 is composed of a concave lens and a convex lens. After the laser beam passes through the concave lens for divergence and the convex lens for collimation in sequence, the beam diameter is expanded and the divergence angle is reduced, thereby obtaining a laser beam with better parallelism. The expanded laser beam is beneficial to subsequent optical path transmission and focusing, and can improve the energy density of the focused spot without increasing the beam divergence angle.

[0025] The phase modulation element 3 is located in the output optical path of the beam expander 2 and is used to modulate the polarization direction of the laser beam. The phase modulation element 3 is preferably a half-wave plate, i.e., a half-wave plate. A half-wave plate is an optical element made using the birefringence effect of a crystal. When linearly polarized light passes through the half-wave plate in a specific direction, its polarization direction will be deflected. The deflection angle is twice the angle between the incident polarization direction and the optical axis of the half-wave plate. The half-wave plate can rotate around its central axis. By rotating the half-wave plate, the amount of modulation on the polarization direction of the incident laser beam can be continuously changed, thereby precisely adjusting the polarization direction of the output laser beam. In this embodiment, the phase modulation element 3 is not only used to adjust the polarization direction of the laser beam to form an angle of 12°-25° with the normal to the surface of the product to be processed, but also to compensate in real time for random fluctuations in the polarization direction of the laser 1 caused by temperature drift and changes in operating current. This allows for monitoring the output polarization state of the laser 1 and feedback control of the rotation angle of the half-wave plate, dynamically maintaining the stability of the final output polarization direction, thereby ensuring the consistency of the thermal deposition effect during long-term processing. Furthermore, the rotation angle of the phase modulation element 3 must be matched with the installation angle θ of the reflector 6: since the reflection of the reflector 6 will change the reference direction of the polarization coordinate system, rotating the half-wave plate alone cannot directly control the polarization direction that finally reaches the product surface. Only by coordinating the modulation amount of the half-wave plate with the turning angle of the reflector 6 can we ensure that the polarization direction that finally hits the ink layer forms a target angle with the normal of the product surface. The half-wave plate and the reflector together constitute a "polarization-angle linkage compensation system", and neither can be missing.

[0026] The scanning galvanometer 4 is disposed in the output optical path of the phase modulation element 3 and is used to drive the laser beam to deflect so that the laser beam scans along a preset processing trajectory. The scanning galvanometer 4 is provided with an X-axis lens and a Y-axis lens. The X-axis lens and the Y-axis lens are driven by independent servo motors and can swing at high speed in two orthogonal directions. When the laser beam is incident on the X-axis lens and the Y-axis lens, by controlling the swing angle of the two lenses, the deflection direction and deflection amount of the reflected beam in the two-dimensional plane can be precisely controlled, so that the laser beam can perform high-speed scanning on the surface of the product to be processed along the preset processing trajectory. Under the combined action of the X-axis lens and the Y-axis lens, the laser beam can accurately remove the ink layer along any preset graphic trajectory.

[0027] The scanning lens 5 is disposed in the output optical path of the scanning galvanometer 4 and is used to focus the laser beam. The scanning lens 5 is preferably a flat-field scanning lens, i.e., an F-theta lens. Its characteristic is that the focused spot always remains on the same focal plane within the scanning field of view, and the scanning angle is linearly related to the position of the spot on the focal plane, which facilitates precise pattern scanning in conjunction with the scanning galvanometer 4. When the laser beam is focused by the scanning lens 5, the energy density is greatly increased, forming a focused spot with extremely high energy density, which can instantly vaporize the ink material. In this invention, the combination of the scanning galvanometer 4 and the scanning lens 5 also serves as an additional aberration pre-compensation mechanism: since the beam is tilted and deflected by the reflector 6, the beam actually incident on the scanning lens 5 is not completely perpendicular, which introduces a certain off-axis aberration. The control system calculates the aberration distribution generated by the scanning lens 5 at different field positions in advance according to the preset tilt angle α of the reflector 6, and adjusts the deflection timing of the X-axis and Y-axis lenses of the scanning galvanometer 4 so that the beam enters different areas of the scanning lens 5 at different incident angles, thereby canceling the aberration introduced by the tilt of the reflector. The scanning galvanometer 4 not only undertakes the basic function of beam deflection scanning, but also acts as a dynamic aberration compensator, ensuring the consistency of the focused spot quality across the entire field of view.

[0028] The reflector 6 is positioned in the output optical path of the scanning lens 5 to deflect the laser beam at a preset angle relative to the normal of the surface of the product to be processed. In this embodiment, to achieve an output angle α of 12°-25° relative to the normal of the product surface, the installation angle θ of the reflector 6 satisfies θ = 45° - α / 2, i.e., θ is 32.5°-39°. The installation angle θ of the reflector 6 refers to the angle between the mirror axis of the reflector 6 and the laser beam incident on the reflector 6. According to the law of reflection of a plane mirror, the angle of incidence equals the angle of reflection. After the laser beam is deflected by the reflector 6, the angle between the output direction and the incident direction is twice the angle of incidence of the reflector 6. By setting the installation angle θ of the reflector 6 to the aforementioned range, the horizontally transmitted focused laser beam can be precisely redirected to exit at an angle of 12°-25° relative to the normal of the product surface. The reflector 6 in this invention has two main functions: First, the tilted installation of the reflector 6 changes the laser beam, which was originally incident perpendicularly to the product surface, into an tilted incident beam. It is this "tilt" that allows the laser beam to form a conical focused beam after entering the ink layer. If the reflector 6 is not tilted, the laser beam, being incident perpendicularly, cannot form a conical beam, and the thermal stress coupling effect will not be triggered. In other words, the tilt angle of the reflector 6 directly determines whether the thermal stress coupling effect occurs and its strength, rather than merely changing the direction of the optical path. Secondly, while redirecting the optical path, the reflector 6 also acts as a polarization purifier. When linearly polarized light is reflected by the reflector at a non-perpendicular angle (close to the Brewster angle), there is a significant difference in reflectivity between the S-polarization and P-polarization components in the reflected light. The tilted installation of the reflector 6 preferentially retains the polarization component perpendicular to the incident plane, while the polarization component parallel to the incident plane is partially lost through transmission. This secondary screening and purification of polarization direction during reflection further enhances the polarization purity of the laser beam ultimately incident on the product surface, making the thermal deposition effect more significant. The mirror surface of the reflector 6 is preferably coated with a high-reflectivity coating to reduce laser energy loss during reflection.

[0029] In this embodiment, the laser 1 and the beam expander 2 are coaxially arranged, the phase modulation element 3 is placed horizontally, and its surface normal is parallel to the axis of the beam expander 2 and the laser 1. The axis of the scanning galvanometer 4 is perpendicular to the axis of the beam expander 2, and the axis of the scanning lens 5 is coaxial with the axis of the scanning galvanometer 4. This makes the entire optical path system compact and the optical axis accurately aligned, ensuring that the energy loss of the laser beam is minimized during transmission.

[0030] In a preferred embodiment of the present invention, the device further includes an industrial camera and a lens, which are positioned above the reflector 6 for aligning the product to be processed. The industrial camera captures an image of the product, and an image processing algorithm identifies positioning marks on the product, such as crosshairs or borders, to calculate the product's positional and angular deviations. Based on the identification results from the industrial camera, the control system controls the scanning galvanometer 4 to adjust the starting position and trajectory direction of the laser beam, achieving precise alignment between the laser-processed graphic and the product, thus ensuring processing accuracy. Example

[0031] The present invention also provides a method for removing ink from the surface of a transparent material using a laser. This method is implemented based on the above-mentioned apparatus, and the specific operation steps are described in detail below.

[0032] Step S1: Provide the product to be processed; the product is a transparent material with an ink layer covering its surface. The transparent material can be glass, sapphire, transparent ceramic, or other materials with a certain degree of light transmittance. The ink layer can be formed on the surface of the transparent material by methods such as screen printing, spraying, or pad printing. The ink layer can be a single-layer structure or a multi-layer structure. After the product is placed in the processing station, an industrial camera is used to photograph and position the product, identifying its precise position and angle to provide a positional reference for subsequent laser scanning.

[0033] Step S2: Laser beam expansion, polarization modulation, deflection scanning, and focusing; Laser 1 provides a laser beam, and beam expander 2 expands the laser beam. After passing through beam expander 2, the laser beam emitted from laser 1 has an enlarged beam diameter and a reduced divergence angle, resulting in a laser beam with better parallelism. The expanded laser beam can maintain a small divergence angle during transmission, which is beneficial for maintaining a high energy density in subsequent optical paths. Then, the phase modulation element 3 is used to modulate the polarization direction of the expanded laser beam. The phase modulation element 3 is preferably a half-wave plate. By rotating the half-wave plate, the polarization direction of the laser beam is adjusted so that the polarization direction of the laser beam has a preset polarization deflection angle relative to the surface of the product to be processed. In this embodiment, the phase modulation element 3 modulates the polarization direction of the laser beam so that the modulated polarization direction forms an angle of 12°-25° with the normal of the surface of the product to be processed. This angle range is determined based on the absorption characteristics of the ink material for polarized light and the optimal conditions of thermal stress coupling effect. When the polarization direction is within this angle range with the normal of the product surface, the laser beam can produce the best thermal deposition effect inside the thin film after entering the ink layer. Furthermore, the rotation angle of the phase modulation element 3 is not set independently, but is linked and matched with the installation angle θ of the reflector 6. Since the spatial reference frame of the polarization direction rotates after the laser beam is reflected by the reflector 6, the modulation amount of the half-wave plate and the turning angle of the reflector 6 must be coordinated and corrected to ensure that the polarization direction finally reaching the surface of the ink layer maintains the target angle with the normal of the product surface. The scanning galvanometer 4 then drives the modulated laser beam to deflect, causing the laser beam to scan along a preset processing trajectory. The scanning galvanometer 4 is equipped with an X-axis lens and a Y-axis lens. The control system generates scanning trajectory data according to the preset processing pattern and controls the swing angle of the X-axis lens and the Y-axis lens respectively, so that the laser beam scans at high speed along the preset trajectory in a two-dimensional plane. At the same time, the control system also calculates the off-axis aberration distribution caused by the tilted incident light of the scanning lens 5 in advance according to the preset tilt angle α of the reflector 6. By adjusting the deflection timing of the scanning galvanometer 4, the aberration is dynamically pre-compensated, so that the scanning galvanometer 4, in addition to performing the basic function of trajectory scanning, also acts as an aberration compensator. Finally, the deflected laser beam is focused by the scanning lens 5; preferably, the scanning lens 5 is a flat-field scanning lens, which focuses the laser beam into a spot with higher energy density to achieve the purpose of instantaneous vaporization of materials.

[0034] Step S3: The laser beam is emitted at an angle and ablates and removes the ink layer; The focused laser beam is deflected by the reflector 6, causing it to exit at a preset angle relative to the surface normal of the product and onto the ink layer, thus ablating and removing the ink layer. In this embodiment, the preset angle is the angle α between the laser beam and the surface normal, where α is 12°-25°. The installation angle θ of the reflector 6 satisfies θ=45°-α / 2 with the angle α. When α is 12°-25°, θ is 32.5°-39°. In this embodiment, after the laser beam with a specific polarization direction enters the ink layer at an angle, it forms a conical focused beam inside the residual film. Because the polarization direction is at a specific angle to the surface normal, the electric field component of the laser is distributed along a specific direction inside the film. After absorbing the laser energy, the film generates thermal deposition, which enhances the internal temperature rise of the film and leads to the occurrence of thermal stress coupling, thereby causing structural damage to the film. The damaged film is more easily ablated and vaporized by the laser. By simultaneously coordinating the movement of the laser trajectory, the purpose of completely removing the ink within the set pattern trajectory can be achieved.

[0035] In a preferred embodiment of the present invention, in step S3, after the reflector 6 deflects the laser beam, it also performs real-time correction and compensation on the preset processing trajectory according to the preset tilt angle, so that the actual processing contour formed by the laser beam scanning on the ink layer is consistent with the preset pattern. Specifically, since the laser beam is incident on the product surface at an tilt angle, the projection position of the light spot on the scanning plane will produce geometric distortion compared to when it is incident perpendicularly; there is a proportional deviation between the actual step size and the preset step size in the scanning direction, and the amount of deviation changes with the incident angle and the scanning position. Therefore, the control system establishes a coordinate transformation model in advance according to the tilt angle α, and performs correction and compensation calculations on each coordinate point of the preset processing trajectory to eliminate the pattern distortion caused by the tilted incident. Furthermore, the aforementioned correction and compensation does not rely solely on open-loop calculations of the mathematical model, but rather on closed-loop feedback correction through an industrial camera positioned above the reflector 6. Before processing, the industrial camera captures images of the positioning marks and preset processing graphic areas on the product, obtaining the actual image coordinates of the product surface. The control system calculates the actual distortion based on the imaging results from the industrial camera and incorporates this distortion into the coordinate transformation model for correction. During or after processing, the industrial camera again captures images of the processing area, comparing the actual processing contour with the preset graphic. If a deviation exists, online compensation is performed by adjusting the scanning trajectory of the scanning galvanometer 4. In this method, the industrial camera not only performs the basic function of product alignment but also acts as a distortion measuring instrument and an online processing quality detector, achieving an upgrade from an "open-loop mathematical model" to "closed-loop real-time feedback" in correction and compensation. The corrected scanning trajectory ensures that the actual processing contour formed by the laser beam on the ink layer is consistent with the preset graphic, guaranteeing the product's processing accuracy.

[0036] The viewing area processed using this method shows no film residue that can be detected visually. This is because the tilted laser beam with a specific polarization direction generates a thermal stress coupling destruction effect inside the film, causing the residual film to be completely destroyed and vaporized, rather than relying solely on laser ablation for removal as in existing technologies, where the absorption rate drops sharply as the ink thins, leading to residue. This method solves the problem of the difficulty in removing transparent films from a physical mechanism. Working principle description The principle of the present invention will be explained below in conjunction with the overall working process of the present invention: The laser beam emitted by laser 1 is first expanded by beam expander 2 to obtain a beam with better parallelism. Then, the laser beam enters phase modulation element 3, where the polarization direction is adjusted by rotating a half-wave plate to make the polarization direction form an angle of 12°-25° with the normal to the product surface. The polarization-modulated laser beam enters scanning galvanometer 4, which deflects and scans along a preset processing trajectory under the influence of X-axis and Y-axis mirrors. The scanned laser beam is then focused by scanning lens 5 to form a high-energy-density focused spot. Finally, the focused laser beam is deflected by reflector 6 and exits at an angle of 12°-25° relative to the normal to the product surface onto the ink layer on the surface of the product to be processed. After the tilted laser beam with a specific polarization direction enters the ink layer, due to the angle between the laser's polarization direction and the normal direction of the thin film interface, the electric field component of the laser is distributed along a specific direction inside the thin film. This significantly improves the absorption efficiency of the laser energy in the thin film, resulting in a thermal deposition effect inside the film. This thermal deposition causes a sharp increase in the internal temperature of the thin film, and due to the difference in thermal expansion coefficients between the thin film and the transparent substrate, thermal stress is generated inside the thin film. The accumulation of thermal stress triggers a thermal stress coupling process, causing structural damage to the thin film. This results in microcracks within the film, reduced interfacial adhesion, and a looser film structure after thermal stress damage. This looser structure further increases the film's absorption rate to the laser, making it more susceptible to ablation and vaporization by subsequent laser energy. This physical mechanism fundamentally solves the problem in existing technologies where the ink thins, causing a sharp drop in laser absorption rate and making it impossible to remove residual film. Simultaneously, because the laser beam is incident at an angle, the projection of the light spot onto the scanning plane produces geometric distortion. The control system performs real-time correction and compensation of the processing trajectory based on the preset tilt angle, ensuring that the actual processing contour formed by the laser beam on the ink layer matches the preset pattern, thus guaranteeing processing accuracy.

[0037] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Anyone skilled in the art can readily implement the present invention based on the accompanying drawings and the above description. However, any modifications, alterations, and variations made by those skilled in the art without departing from the scope of the present invention using the disclosed technical content are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and variations made to the above embodiments based on the essential technology of the present invention are still considered part of the technical solution of the present invention.

Claims

1. An apparatus for removing ink from the surface of a transparent material using a laser, characterized in that: The system includes a laser, a beam expander, a phase modulation element, a scanning galvanometer, a scanning lens, and a reflector. The laser emits a laser beam. The beam expander is positioned in the emission path of the laser to expand the laser beam. The phase modulation element is located in the output path of the beam expander to modulate the polarization direction of the laser beam. The scanning galvanometer is positioned in the output path of the phase modulation element to deflect the laser beam so that it scans along a preset processing trajectory. The scanning lens is positioned in the output path of the scanning galvanometer to focus the laser beam. The reflector is positioned in the output path of the scanning lens to deflect the laser beam at a preset angle relative to the surface normal of the product to be processed.

2. The apparatus for removing ink from the surface of a transparent material using a laser according to claim 1, characterized in that: The tilt angle is set to be the angle α between the laser beam being deflected and the normal to the surface of the product to be processed, which is 12°-25°.

3. The apparatus for removing ink from the surface of a transparent material using a laser according to claim 2, characterized in that: The installation angle θ of the reflector is the angle between the axis of the reflector and the emitted laser beam of the scanning lens, and the installation angle θ of the reflector satisfies θ = 45° - α / 2.

4. The apparatus for removing ink from the surface of a transparent material using a laser according to claim 3, characterized in that: The installation angle θ of the reflector is 32.5°-39°.

5. The apparatus for removing ink from the surface of a transparent material using a laser according to claim 1, characterized in that: The laser and beam expander are coaxially arranged. The phase modulation element is placed horizontally with its surface normal parallel to the axes of the beam expander and the laser. The axis of the scanning galvanometer is perpendicular to the axis of the beam expander. The axis of the scanning lens is coaxial with the axis of the scanning galvanometer.

6. The apparatus for removing ink from the surface of a transparent material using a laser according to claim 1, characterized in that: The phase modulation element is a half-wave plate, and the scanning galvanometer is equipped with an X-axis lens and a Y-axis lens.

7. A method for removing ink from the surface of a transparent material using a laser, characterized in that: The apparatus for removing ink from the surface of a transparent material using a laser, according to any one of claims 1-6, comprises the following steps: S1. Provide a product to be processed, wherein the product to be processed is a transparent material product and the surface is covered with an ink layer; S2. A laser beam is provided by a laser, the laser beam is expanded by the laser beam, and then the polarization direction of the expanded laser beam is modulated by a phase modulation device. Then, a scanning galvanometer is used to drive the modulated laser beam to deflect, so that the laser beam scans along a preset processing trajectory. Finally, the deflected laser beam is focused by a scanning lens, so that the polarization direction of the laser beam has a preset polarization deflection angle relative to the surface of the product to be processed. S3. The focused laser beam is deflected by the reflector, so that the laser beam is emitted at a preset angle relative to the surface normal of the product to be processed and onto the ink layer on the surface of the product to be processed, thereby ablation and removal of the ink layer on the product to be processed.

8. The apparatus for removing ink from the surface of a transparent material using a laser according to claim 7, characterized in that: In step S2, the phase modulation device modulates the polarization direction of the laser beam so that the modulated polarization direction forms an angle of 12°-25° with the surface normal of the product to be processed.

9. The apparatus for removing ink from the surface of a transparent material using a laser according to claim 7, characterized in that: In step S2, after the laser beam is provided by the laser, the laser beam is expanded by a beam expander, its polarization direction is modulated by a phase modulation element, it is deflected by a scanning galvanometer, and it is focused by a scanning lens before being emitted to the reflecting mirror.

10. The apparatus for removing ink from the surface of a transparent material using a laser according to claim 7, characterized in that: In step S3, after the reflector deflects the laser beam, it performs real-time correction and compensation on the preset processing trajectory according to the preset tilt angle, so that the actual processing contour formed by the laser beam scanning on the ink layer is consistent with the preset pattern.

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