Method and system for precise marking of transparent materials using frequency-locked single-pulse infrared ultrafast laser

Abstract

The present invention provides a method and system for precision marking transparent materials using a frequency-locked single-pulse infrared ultrafast laser. The method comprises the following steps: 1) providing an ultrafast laser capable of emitting high-energy single pulses at a high repetition rate with high single-pulse energy consistency, wherein the frequency is 10 kHz to 200 kHz and the single-pulse energy is 50 μJ to 1000 μJ; 2) locking the emission frequency to a constant value; 3) setting the laser wavelength to 1064 ± 5 ​​nm; 4) inputting the ultrafast laser through a shaping optical path and a beam transmission optical path into a galvanometer, and then focusing the ultrafast laser through a field lens on the surface or interior of the transparent material; and 5) completing the marking under the control of a hardware and software controller. The marking method of the present invention achieves marking by vaporizing the material processing surface with a high single-pulse energy ultrafast laser, with virtually no heat-affected zone (HAZ) and without the need for auxiliary powder or other materials. The marking content is fine and clear, and the substrate strength is not affected.

Description

Technical Field

[0001] The present invention relates to the technical field of laser marking, and in particular to a method and system for precisely marking transparent materials with a frequency-locked uniform-energy single-pulse infrared ultrafast laser. Background Art

[0002] Laser marking technology can be used to mark transparent materials (such as glass, sapphire, etc.) and is widely used in many fields such as consumer electronics, automobiles, aerospace, construction, and home life. Therefore, the market demand space is broad and the development potential needs to be explored.

[0003] Currently, laser marking technology for transparent materials primarily utilizes CO2 lasers, green nanosecond lasers, ultraviolet nanosecond lasers, or ultrafast fiber laser-based marking machines, which damage the surface of the transparent material. These marking methods utilize a heat-induced melting effect, but the presence of a heat-affected zone (HAZ) can cause slag, cracks, and chipping on the processed surface, resulting in unclear markings, weakened material strength, and even loosening of the substrate.

[0004] When marking with an ultrafast fiber laser, the pulse width is typically in the picosecond or hundreds of femtosecond range. To meet the high-energy processing threshold for hard, brittle, and transparent materials like glass, the average power must be increased, requiring a repetition frequency ranging from several hundred kHz to 1 MHz or even above 1 GHz. Excessively fast frequencies, when combined with the operating frequency range of conventional galvanometers, which range from a few kHz to tens of kHz to several hundred kHz, can lead to mismatching and result in missed points, missing marks, and even misaligned marking timing. Furthermore, to compensate for the low energy of a single pulse, a pulse train output mode is often used at the same repetition frequency. Because the start times of the individual pulses within the train are sequential, appearing sequential in the time domain, the specific marking location on the workpiece surface is affected by this time sequence, resulting in corresponding spatial drift. Furthermore, the energy of each individual pulse within the train generally fluctuates significantly, resulting in poorly consistent marking on the workpiece surface, reducing both quality and effectiveness. Glass, a hard, brittle, transparent material, can easily darken or develop discolored color centers when exposed to laser pulse trains during marking, resulting in dark marks. This can even partially alter the characteristic parameters of the glass material, making the substrate porous. After multiple pulse trains, the illuminated area darkens further, eventually forming a darkened edge around it and weakening the material. Summary of the Invention

[0005] In view of this, in order to overcome the deficiencies of the prior art, the present invention provides a method for precisely marking transparent materials using a frequency-locked, uniform-energy single-pulse infrared ultrafast laser.

[0006] The method for precisely marking transparent materials with a frequency-locked uniform energy single-pulse infrared ultrafast laser according to the present invention comprises the following steps:

[0007] 1) An ultrafast laser capable of emitting high-energy single pulses at a high repetition rate with high single-pulse energy consistency is provided, wherein the high repetition rate is 10 kHz to 200 kHz, the high-energy single pulse energy is 50 uJ to 1000 uJ, and the single-pulse energy consistency is: the energy difference between single pulses is ≤ ±5%;

[0008] 2) Lock the transmission frequency to a certain value between 10KHz-200KHz;

[0009] 3) Set the laser wavelength to 1064±5nm;

[0010] 4) The ultrafast laser emitted by the laser is amplified by the beam shaping path, input to the galvanometer through the beam transmission path, and then focused on the surface or interior of the transparent material workpiece on the workpiece support platform after passing through the F-θ field lens;

[0011] 5) Under the control of the software and hardware controller, set the laser parameters and processing parameters; control the galvanometer and laser emission to complete the laser marking of the marking pattern on the surface or inside of the transparent material.

[0012] The frequency-locked uniform energy single pulse described in the present invention refers to a laser operating mode in which a uniform energy single pulse is periodically output at a locked frequency.

[0013] The laser is an all-solid-state picosecond laser.

[0014] The single pulse width is 1-10 ps.

[0015] The laser window spot size is 1-3 mm, and the divergence angle is 0.5-1.5 mrad.

[0016] The shaping light path is a beam expanding light path with a magnification of 1-8 times.

[0017] The light beam transmission optical path is composed of a transmission optical path with a transmission distance of 10-1000 mm.

[0018] The operating frequency of the galvanometer is 10k-400k, and the lens size of the galvanometer is 5-30mm.

[0019] The field lens is an F-θ field lens or a telecentric field lens, and has a focal length of 30-300 mm.

[0020] The minimum resolution feature size of the microstructure forming the marking pattern is 1-30 μm.

[0021] The present invention also provides a marking system for realizing the above-mentioned method for precision marking transparent materials, wherein the system comprises an ultrafast laser, a shaping optical path and a beam transmission optical path, a focusing lens, a workpiece carrier, and a controller.

[0022] The ultrafast laser is an ultrafast laser that can emit high-energy single pulses at a high repetition frequency and has high single-pulse energy consistency. The high repetition frequency is 10 kHz to 200 kHz, the high-energy single pulse energy is 50 uJ to 1000 uJ, and the single-pulse energy consistency is ≤ ±5%. The emission frequency is locked to a certain value between 10 kHz and 200 kHz. The laser wavelength is set to 1064 ± 5 ​​nm.

[0023] The focusing lens includes a scanning galvanometer for controlling the deflection of the laser beam and a field lens for focusing the laser beam;

[0024] The workpiece carrier is fixed on a six-axis motion system, which includes a linear motor unit that controls the translation of the workpiece carrier in the X, Y, and Z directions, and a rotating platform unit in the Rx, Ry, and Rz directions;

[0025] The laser is connected to a computer controller installed with laser marking system software via a data cable. The computer controller inputs the controlled laser power, scanning speed, and repetition frequency signals to the laser, receives the laser's pulse synchronization signal, and simultaneously controls the optical path, galvanometer, field mirror, and six-axis motion system to complete the marking.

[0026] An optical gate is provided between the shaping optical path and the light beam transmission optical path, and its opening and closing is controlled by a controller.

[0027] The method of the present invention can be used for precise marking on the surface or inside of transparent materials, in particular on the surface or inside of glass, crystal or acrylic.

[0028] The beneficial effects of the present invention are:

[0029] 1. The present invention is based on a locked ultrafast laser marking method with high repetition frequency, single pulse operation, high single pulse energy, and high single pulse energy consistency. It can be used for precision marking on the surface or inside of transparent materials such as glass, crystal, acrylic, etc., and can meet a wide variety of needs.

[0030] 2. The present method achieves marking by vaporizing the material surface with a high single-pulse energy ultrafast laser, rather than by melting it. Consequently, there is virtually no heat-affected zone, and the surface is virtually free of slag, cracks, or chipping. The method also eliminates the need for auxiliary powders, resulting in fine, clear markings and virtually unchanged material strength.

[0031] 3. The high-energy single pulse output by the marking method of the present invention is unique in the time domain. The specific position point of the workpiece material processing surface during marking is very accurate and will not drift in space. The marking quality is very good.

[0032] 4. The marking method of the present invention has a fast processing time, almost no missed points or marks occur, and the timing matching is accurate.

[0033] 5. Under the irradiation of the ultrafast laser device with high single-pulse energy consistency of the present invention, the optical processing process is consistent, and the surface of transparent materials such as glass is clear and bright. There is no repeated irradiation, the material hardly darkens, and the characteristic parameters of the material hardly change. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic diagram of the system structure of the present invention for precise marking of transparent materials using a frequency-locked, uniform-energy single-pulse infrared ultrafast laser;

[0035] Including: 1. Ultrafast laser; 2. Optical path; 2-1. Shaping optical path; 2-2. Beam transmission optical path; 3. Galvanometer; 4. Field mirror; 5. Marking workpiece; 6. Workpiece carrier; 7. Controller; 8. Reflector;

[0036] Figure 2 This is a photo of the precise marking effect of a "tiger head" pattern on a glass surface using the frequency-locked uniform energy single-pulse infrared ultrafast laser marking method of the present invention;

[0037] Figure 3 This is a photo of the precise marking effect of a "three-dimensional floor plan" pattern on the inside of glass using the frequency-locked uniform energy single-pulse infrared ultrafast laser marking method of the present invention;

[0038] Figure 4 This is a photo of the effect of marking a hole array on glass using the frequency-locked uniform energy single-pulse infrared ultrafast laser marking method of the present invention;

[0039] FIG5 is a photograph showing the effect of precise marking of a microhole array on glass using the frequency-locked uniform energy single-pulse infrared ultrafast laser marking method of the present invention;

[0040] Among them: 5A. Appearance of microhole array precision marking on glass, 5B. Field of view under microscope with 100x magnification;

[0041] FIG6 is a photograph showing the effect of precisely marking a “QR code” pattern inside a crystal using the frequency-locked uniform energy single-pulse infrared ultrafast laser marking method of the present invention;

[0042] Among them: 6A. is a front view of the crystal block; 6B. is a side view of the crystal block; 6C. is a back view of the crystal block; 6D. is a top view of the crystal block. DETAILED DESCRIPTION

[0043] The frequency-locked uniform energy single-pulse infrared ultrafast pulse provided by the present invention is described below with reference to the accompanying drawings and specific embodiments.

[0044] The laser glass precision marking method and system are further explained without limiting the present invention to the following examples.

[0045] The frequency-locked uniform energy single-pulse infrared ultrafast laser precision marking method of the present invention comprises the following steps:

[0046] 1) An ultrafast laser capable of emitting high-energy single pulses at a high repetition rate with high single-pulse energy consistency is set. The high repetition rate is 10 kHz to 200 kHz, the high-energy single pulse energy is 50 uJ to 1000 uJ, and the single-pulse energy consistency is ≤ ±5%;

[0047] 2) Lock the transmission frequency to a certain value between 10KHz-200KHz;

[0048] 3) Set the laser wavelength to 1064±5nm;

[0049] 4) The ultrafast laser emitted by the laser is amplified by the beam shaping path, then input to the galvanometer through the beam transmission path, and then focused on the surface or interior of the transparent material on the workpiece carrier after passing through the field lens;

[0050] 5) Under the control of the software and hardware controller, set the laser parameters and processing parameters; control the galvanometer and laser emission to complete the laser marking of the marking pattern on the surface or inside of the transparent material.

[0051] The single pulse width is 1-10ps.

[0052] The laser window spot is 1-3mm and the divergence angle is 0.5-1.5mrad.

[0053] The shaping optical path is a beam expanding optical path with a magnification of 1-8 times.

[0054] The light beam transmission path is composed of a transmission light path with a transmission distance of 10-1000mm.

[0055] The operating frequency of the galvanometer is 10k-400k, and the lens size of the galvanometer is 5-30mm.

[0056] The field lens is an F-θ field lens or a telecentric field lens with a focal length of 30-300mm.

[0057] The minimum resolution feature size for forming the microstructure of the marking pattern is 1-30um.

[0058] Step 5) includes the following steps:

[0059] 1. Set the laser emission parameters and the laser pulse synchronization signal in the form of a level, and send the laser pulse synchronization signal and the start time T1 to the software and hardware controller as the processing reference time;

[0060] 2. Debugging the laser beam: The beam passes through the beam transmission, optical shutter and shaping optical path, and the optical shutter is controlled by TTL level; the software and hardware controller sends a signal to control the opening and closing of the optical shutter and the start time T2;

[0061] 3. Debug the galvanometer: The software and hardware controller sends the galvanometer's 5V high and low level control signal and the start time T3 to the galvanometer.

[0062] 4. Adjust the laser beam, focus it near the workpiece carrier through the field lens, and work within the effective range of the field lens.

[0063] 5. Secure the workpiece carrier tightly to the six-axis motion system and the target workpiece onto the carrier. Precisely adjust the position and boundaries of the carrier and calibrate the movement path. Focus the laser near the workpiece and apply it to the workpiece to be marked, allowing it to wait for processing.

[0064] 6. Use computers, microcontrollers, ARM or mobile phones to realize manual or automatic input and output to control the software and hardware controllers.

[0065] 7. Decompose the content to be marked through the software and hardware controller to obtain pixels, diameter, fill density, routing path and graphics in a readable format, and its boundary range is limited to no more than the area boundary of the laser marking machine.

[0066] 8. According to the content and order of the sliced ​​graphics, the laser synchronization signal is input to the software and hardware controller as the time reference, and the coordinates of the workpiece carrier are calibrated as the space reference. The software and hardware controller sequentially transmits control signals, time reference, delay time and control signal timing to the galvanometer, optical gate and six-axis motion system to perform overall timing calibration and preliminary proofing.

[0067] 9. Based on the preliminary proofing results, verify the degree of conformity with the preset results. If there are any differences, fine-tune the process and parameters of each component until the effect is optimal, lock the parameters, and start marking.

[0068] The present invention also provides a marking system for realizing the above-mentioned method for precisely marking transparent materials, comprising an ultrafast laser 1, a shaping optical path 2-1 and a beam transmission optical path 2-2, focusing lenses 3 and 4, a workpiece carrier 6, and a controller 7.

[0069] Ultrafast laser 1 is an ultrafast laser capable of emitting high-energy single pulses at a high repetition rate with high single-pulse energy consistency. The high repetition rate is 10 kHz to 200 kHz, the high-energy single pulse energy is 50 uJ to 1000 uJ, and the single-pulse energy consistency is ≤ ±5%. The emission frequency is locked to a certain value between 10 kHz and 200 kHz. The laser wavelength is set to 1064 ± 5 ​​nm.

[0070] The beam transmission is completed by the reflector 8;

[0071] The focusing lens includes a scanning galvanometer 3 for controlling the deflection of the laser beam and a field lens 4 for focusing the laser beam;

[0072] The workpiece carrier 6 is fixed on a six-axis motion system, which includes a linear motor unit that controls the translation of the workpiece carrier in the X, Y, and Z directions, and a rotating platform unit in the Rx, Ry, and Rz directions;

[0073] The ultrafast laser 1 is connected to a computer controller 7 installed with the laser marking system software via a data line. The computer inputs the controlled laser power, scanning speed, and repetition frequency signals to the laser 1, and receives the laser pulse synchronization signal. At the same time, it controls the optical path 2, galvanometer 3, field lens 4, and the transparent material workpiece 5 on the six-axis motion system to complete the marking. Figure 1 shown.

[0074] An optical gate is provided between the shaping optical path and the light beam transmission optical path, and its opening and closing is controlled by a controller.

[0075] Example 1: Precision marking of a “tiger head” pattern on a glass surface

[0076] Laser 1 is connected via a data cable to a computer installed with laser marking system software. The computer inputs signals for controlling laser power, scanning speed, and repetition rate to the laser, which is a fully solid-state picosecond laser. Controller 7 receives the laser's pulse synchronization signals and simultaneously controls optical path 2, galvanometer 3, field lens 4, and the six-axis motion system to complete the marking process.

[0077] The locked transmission frequency is 50KHz, the single pulse energy is 50uJ, and the single pulse width is 10ps.

[0078] The laser 1 window spot size is 2 mm and the divergence angle is 1.0 mrad.

[0079] The shaping optical path 2-1 is a beam expanding optical path with a magnification of 5 times.

[0080] The light beam transmission path 2-2 is composed of a transmission light path with a transmission distance of 500 mm.

[0081] The operating frequency of the galvanometer is 10k and the lens size of the galvanometer is 18mm.

[0082] The field lens is an F-θ field lens with a focal length of 50 mm.

[0083] The minimum resolution feature size of the microstructure forming the marking pattern is 4 μm.

[0084] Marking with the above lasers:

[0085] (1) Import the image to be marked into the computer;

[0086] (2) Read the image to be marked through the laser marking system software installed on the computer, and set the laser output power, galvanometer operating frequency and laser repetition frequency;

[0087] (3) Turn on the laser, and the laser motion control system scans according to the image signal output by the computer. The high-energy laser beam passes through the transparent material 5 to perform laser marking on the working surface.

[0088] Marking effect Figure 2 shown.

[0089] Example 2: Precision marking of a "3D floor plan" pattern inside glass

[0090] It is basically the same as Example 1, except that:

[0091] The locked transmission frequency is 10KHz, the single pulse energy is 1000uJ, and the single pulse width is 1ps.

[0092] The laser 1 window spot size is 3 mm and the divergence angle is 1.5 mrad.

[0093] The shaping optical path 2-1 is a beam expanding optical path with a magnification of 8 times.

[0094] The light beam transmission path 2-2 is composed of a transmission light path with a transmission distance of 1000 mm.

[0095] The operating frequency of the galvanometer 3 is 50k, and the lens size of the galvanometer is 30mm.

[0096] The field lens 4 is an F-θ field lens with a focal length of 300 mm.

[0097] The minimum resolution feature size of the microstructure forming the marking pattern is 2 μm.

[0098] Marking effect Figure 3 shown.

[0099] Example 3: Marking of hole arrays on glass

[0100] It is basically the same as Example 1, except that:

[0101] The locked transmission frequency is 200KHz, the single pulse energy is 300uJ, and the single pulse width is 10ps.

[0102] The laser 1 window spot size is 1 mm and the divergence angle is 0.5 mrad.

[0103] The shaping optical path 2-1 is a beam expanding optical path with a magnification of 1.

[0104] The light beam transmission path 2-2 is composed of a transmission light path with a transmission distance of 100 mm.

[0105] The operating frequency of the galvanometer 3 is 200k, and the lens size of the galvanometer is 5mm.

[0106] Field lens 4 is a telecentric field lens with a focal length of 30 mm.

[0107] The minimum resolution feature size of the microstructure forming the marking pattern is 8 μm.

[0108] Marking effect Figure 4 shown.

[0109] Example 4: Precision Marking of Microhole Arrays on Glass

[0110] It is basically the same as Example 1, except that:

[0111] The locked transmission frequency is 150KHz, the single pulse energy is 150uJ, and the single pulse width is 10ps.

[0112] The laser 1 window spot size is 1.5 mm and the divergence angle is 1.0 mrad.

[0113] The shaping optical path 2-1 is a beam expanding optical path with a magnification of 8 times.

[0114] The light beam transmission path 2-2 is composed of a transmission light path with a transmission distance of 500 mm.

[0115] The operating frequency of the galvanometer 3 is 100k, and the lens size of the galvanometer is 20mm.

[0116] Field lens 4 is a telecentric field lens with a focal length of 30 mm.

[0117] The minimum resolution feature size of the microstructure forming the marking pattern is 1 μm.

[0118] The marking effect is shown in Figure 5.

[0119] Example 5: Precision marking of a “QR code” pattern inside a crystal

[0120] It is basically the same as Example 1, except that:

[0121] The locked transmission frequency is 100KHz; the single pulse energy is 100uJ and the single pulse width is 8ps.

[0122] The laser 1 window spot size is 2 mm and the divergence angle is 1.0 mrad.

[0123] The shaping optical path 2-1 is a beam expanding optical path with a magnification of 4 times.

[0124] The light beam transmission path 2-2 is composed of a transmission light path with a transmission distance of 300 mm.

[0125] The operating frequency of the galvanometer 3 is 400k, and the lens size of the galvanometer is 20mm.

[0126] The field lens 4 is an F-θ field lens with a focal length of 200 mm.

[0127] The minimum resolution feature size of the microstructure forming the marking pattern is 15 μm.

[0128] The marking effect is shown in Figure 6.

[0129] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the same. Although the present invention has been described in detail with reference to the above embodiments, a person skilled in the art may still modify or make equivalent substitutions to the specific implementations of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the scope of protection of the claims of the present invention to be approved.

Claims

1. A method for precise marking of transparent materials using a frequency-locked, uniform-energy single-pulse infrared ultrafast laser, characterized in that: The frequency-locked uniform energy single pulse refers to the laser working mode of periodically outputting a uniform energy single pulse at a locked frequency, and the single pulse width is 1-10ps; The method comprises the steps of: 1) An ultrafast laser capable of emitting high-energy single pulses at a high repetition rate with high single-pulse energy consistency is provided, wherein the laser is an all-solid-state picosecond laser; the high repetition rate is 10kHz-200kHz, the high-energy single pulse energy is 50uJ-1000uJ, and the single-pulse energy consistency is ≤±5%; 2) Lock the transmission frequency to a certain value between 10kHz and 200kHz; 3) Set the laser wavelength to 1064±5nm; 4) The ultrafast laser emitted by the laser is amplified through a shaping optical path, input to a galvanometer through a beam transmission optical path, and then focused onto the surface or interior of a transparent workpiece on a workpiece support platform after passing through a field lens; the galvanometer operating frequency is 10kHz-400kHz, and the lens size of the galvanometer is 5-30mm; the field lens is an F-θ field lens or a telecentric field lens with a focal length of 30-300mm; 5) Under the control of the software and hardware controller, set the laser parameters and processing parameters; control the galvanometer and laser emission to complete the laser marking of the surface or internal pattern of transparent materials.

2. The method for ultrafast laser precision marking of transparent materials according to claim 1, characterized in that: The laser window spot size is 1-3 mm, and the divergence angle is 0.5-1.5 mrad.

3. The method for ultrafast laser precision marking of transparent materials according to claim 1, characterized in that: The shaping light path is a beam expanding light path with a magnification of 1-8 times.

4. The method for ultrafast laser precision marking of transparent materials according to claim 1, characterized in that: The light beam transmission optical path is composed of a transmission optical path with a transmission distance of 10-1000 mm.

5. The method for ultrafast laser precision marking of transparent materials according to claim 1, characterized in that: The minimum resolution feature size for forming the microstructure of the marking pattern is 1-30um.

6. A marking system for implementing the method for precise marking of transparent materials according to claim 1, characterized in that: The system includes an ultrafast laser, a shaping optical path and a beam transmission optical path, a focusing lens, a workpiece carrier and a controller; The ultrafast laser is an all-solid-state picosecond laser capable of emitting high-energy single pulses at a high repetition rate and with high single-pulse energy consistency. The single pulse width is 1-10 ps; the high repetition rate is 10 kHz-200 kHz, the high-energy single pulse energy is 50 uJ-1000 uJ, and the single-pulse energy consistency is ≤±5%; the emission frequency is locked to a certain value between 10 kHz and 200 kHz; and the laser wavelength is set to 1064±5 nm. The focusing lens includes a scanning galvanometer that controls the deflection of the laser beam and a field lens that focuses the laser beam; the galvanometer operates at a frequency of 10kHz-400kHz, and the lens size of the galvanometer is 5-30mm; the field lens is an F-θ field lens or a telecentric field lens, with a focal length of 30-300mm; the workpiece carrier is fixed on a six-axis motion system, which includes a linear motor unit that controls the translation of the workpiece carrier in the X, Y, and Z directions, and a rotating platform unit in the Rx, Ry, and Rz directions; The laser is connected to a computer controller installed with laser marking system software via a data cable. The computer controller inputs the controlled laser power, scanning speed, and repetition frequency signals to the laser, receives the laser's pulse synchronization signal, and simultaneously controls the optical path, galvanometer, field mirror, and six-axis motion system to complete the marking.

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