Apparatus and method for laser processing transparent materials via PCF

Abstract

The application discloses a device and method for processing transparent materials by laser transmission through PCF, and the processing device comprises a pre-cutting laser, a hollow PCF optical plate, a Bessel cutting head, a galvanometer and a CO2 laser, the hollow PCF optical plate transmits ultrafast laser to the Bessel cutting head and the galvanometer, the CO2 laser is provided with a light emitting head, and the Bessel cutting head, the galvanometer and the light emitting head are arranged on a platform capable of generating vertical and / or horizontal relative motion with a workpiece. The processing method comprises the following steps: using the hollow PCF optical plate as a light guide arm, directly coupling the ultrafast laser to the Bessel cutting head and the galvanometer, and pre-cutting the workpiece, and then separating or polishing the pre-cut workpiece by the CO2 laser. The device and method can realize full-category processing of the workpiece, have high processing speed and efficiency, are stable and reliable in processing, and can process high-quality products.

Description

Technical Field

[0001] This invention relates to the field of laser processing technology, and specifically to a laser processing device and method for transparent materials. Background Technology

[0002] There are as many as 12 processing steps for common transparent materials (such as glass), including cutting, drilling, polishing, engraving, milling, grooving, internal grinding, external grinding, notching, routing, and chamfering. Each processing step has different characteristics, and a CNC engraving machine can complete all of them by switching between different cutter heads. However, CNC engraving machines tend to have larger chipping edges; for glass smaller than 2 mm, its low strength makes it easily damaged during processing, resulting in a low yield; and for small internal patterns, the cutter head is too large to process them.

[0003] Laser processing offers greater versatility, higher processing speed, and greater automation. Patents CN108381043A, CN105149773A, CN108788451A, CN109079348A, and CN110695550A describe nanosecond green light, picosecond green light, and picosecond infrared galvanometer processing technologies. These technologies can perform cutting, drilling, and chamfering on transparent materials such as glass. By analogy, they can also perform engraving, milling, grooving, internal grinding, notching, routing, and chamfering, but not polishing. Furthermore, the galvanometer processing method involves micro-explosion from bottom to top, with each layer feeding only a few micrometers to tens of micrometers, resulting in low processing efficiency, relatively large chipping (approximately tens of micrometers), and small but abundant dust at the blasting points.

[0004] Ultrafast infrared laser combined with a Bezier cutting head enables rapid cutting, and dust-free separation is achieved through CO2 laser dicing. Ultrafast infrared laser combined with a galvanometer allows for rapid drilling, engraving, milling, grooving, internal and external grinding, notching, routing, and chamfering. A standalone CO2 laser can polish glass. Therefore, the combination of ultrafast infrared laser with a Bezier cutting head, galvanometer, and CO2 separation technology can achieve 12 processing steps, resulting in higher efficiency and lower glass processing costs. Existing picosecond infrared lasers combined with Bezier cutting heads are susceptible to dust contamination during picosecond infrared laser combined with galvanometer processing. The lenses can be damaged due to increased contamination absorption, affecting equipment stability. Furthermore, adjusting the spatial optical path is cumbersome and inconvenient to move; for thick glass, the speed and acceleration during movement are low, impacting processing efficiency. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, this invention provides an apparatus and method for laser processing of transparent materials via a hollow PCF (Polycarbonate Fiber Optic Array). The hollow PCF directly couples the light from an ultrafast laser into the Bezier cutting head or galvanometer, transmitting the laser through optical fiber, thus avoiding dust contamination and lens damage. Furthermore, the optical path is plug-and-play, requiring no adjustment like spatial optical paths, resulting in good stability. The lightweight optical fiber allows for rapid three-dimensional movement, with high speed and acceleration, significantly improving processing efficiency.

[0006] This invention discloses an apparatus for laser processing of transparent materials via PCF transmission, comprising a pre-cut laser, a hollow PCF optical plate (PCF, photonic crystal fiber), a Bessel cutting head, a galvanometer, and a CO2 laser. The hollow PCF optical plate transmits ultrafast laser light to the Bessel cutting head and the galvanometer. The CO2 laser is equipped with a light output head. The Bessel cutting head, the galvanometer, and the light output head are all mounted on a platform capable of vertical and / or horizontal relative motion with respect to the workpiece.

[0007] Hollow-core PCFs can be of photonic bandgap type, Kagome type, etc. When used as a light guide, a larger core diameter has advantages in terms of damage threshold or nonlinear effect control; a smaller core diameter supports fewer modes and can have better beam quality at the output end. Different types and sizes can be selected for different workpieces.

[0008] When the hollow PCF is of the photonic bandgap type, the fiber core diameter is 5-10 μm. In the photonic bandgap type hollow PCF, the hollow hole can generate strong energy overlap with the surrounding silicon oxide, which can limit the energy of nanosecond laser pulses to 1 mJ and subpicosecond laser pulses to 1 μJ.

[0009] When the hollow PCF is of the Kagome type, the fiber core diameter is 10-55 μm. Kagome-type hollow PCFs have low energy overlap between the spatial aperture and the surrounding silica, enabling nanosecond laser energy to reach 10 mJ. Preferably, the core diameter is 28 μm or 55 μm. With a core diameter of 55 μm, the mode field diameter is 44 μm, and the fiber is filled with He gas, enabling the transmission of a 700 fs, 1 mJ pulsed laser in a 10 m fiber. Picosecond lasers have a wider pulse width, lower peak power, narrower spectral density, lower dispersion, smaller pulse variation, higher transmitted energy, and more stable pulse width compared to femtosecond lasers.

[0010] Preferably, a coupling module is provided between the pre-cut laser and the Bezier cutting head or galvanometer.

[0011] Preferably, the coupling module includes a laser polarization controller, a PBS (polarized beamsplitter), a first coupling lens, and a second coupling lens. The laser polarization controller and the PBS are sequentially arranged in the output optical path of the pre-cut laser, and the first coupling lens and the second coupling lens are respectively arranged in the reflected optical path and the transmitted optical path of the PBS.

[0012] Preferably, collimating lenses are respectively provided between the hollow PCF optical plate and the Bezier cutting head, and between the hollow PCF optical plate and the galvanometer. The starting points of the two hollow PCF optical plates are located at the rear focal points of coupling lens one and coupling lens two, respectively, and the ending points are located at the front focal point of a collimating lens, respectively.

[0013] Preferably, the hollow PCF output port is equipped with a QBH standard connector (quartz block head, a connector with a quartz block on the fiber end face), and the fiber end is located at the front focal point of the collimating lens.

[0014] Preferably, the laser polarization controller is a half-wave plate or an electro-optic modulator.

[0015] Preferably, the pre-cut laser is a picosecond laser or a femtosecond laser.

[0016] Preferably, the picosecond laser has a wavelength of 1064 nm, a spot size of 1.0 mm, a beam quality factor M2 of less than 1.3, and the polarization direction of the emitted laser is vertical polarization.

[0017] Preferably, the hollow PCF is of the Kagome type.

[0018] A method for laser processing of transparent materials via PCF transmission uses a hollow PCF optical plate as a light guide arm to directly couple an ultrafast laser emitted by a pre-cutting laser to a Bezier cutting head and pre-cut the workpiece. Then, a CO2 laser separates or polishes the pre-cut workpiece.

[0019] A method for laser processing of transparent materials via PCF transmission uses a hollow PCF optical plate as a light guide arm to directly couple an ultrafast laser emitted by a pre-cut laser to a galvanometer, performing drilling, engraving, milling, grooving, internal grinding, external grinding, notching, routing, and chamfering on the workpiece.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] 1. This invention achieves more stable transmission by using a hollow PCF optical plate, and the sealed structure is unaffected by dust. Fiber optic transmission replaces spatial optical path transmission, eliminating the need for reflectors and beam expanders, and eliminating the need for periodic cleaning and maintenance. In spatial optical paths, the beam diverges, resulting in different beam sizes at different processing positions and poor consistency. In contrast, the hollow PCF optical plate transmission system maintains a consistent optical path and beam size across different processing positions, resulting in better consistency. Fiber optic transmission is plug-and-play, and the enclosed structure avoids accidental eye injury during optical path adjustments and use, enhancing safety. Simultaneously, the hollow PCF optical plate can move with the cutting head, flexibly transmitting laser light to achieve three-dimensional curved surface cutting and chamfering. The lightweight cutting head allows for high movement speed and acceleration, resulting in high processing efficiency.

[0022] 2. This invention, by using a pre-cutting laser in conjunction with a Bezier cutting head, enables rapid cutting and dust-free separation through CO2 laser dicing. The pre-cutting laser, in conjunction with a galvanometer, allows for rapid drilling, engraving, milling, grooving, internal and external grinding, notching, routing, and chamfering. The CO2 laser can also be used for glass polishing. Therefore, the combination of the pre-cutting laser, Bezier cutting head, galvanometer, and CO2 laser allows for 12 processing steps, resulting in higher efficiency and lower processing costs. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the technical description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the optical path of the Bezier cutting head of the present invention;

[0025] Figure 2 This is a schematic diagram of the optical path of the coupling module.

[0026] Among them, 11-pre-cut laser, 12-hollow PCF optical plate, 13-Bezier cutting head, 14-Z displacement axis, 15-X displacement axis, 16-Y displacement axis;

[0027] 21-Laser polarization controller, 22-PBS, 23-Coupled lens one, 24-Coupled lens two. Detailed Implementation

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example

[0029] The embodiments disclosed herein involve, but are not limited to, processing steps such as cutting, drilling, polishing, engraving, milling, grooving, inner grinding, outer grinding, notching, routing, and chamfering of transparent materials such as glass.

[0030] When using lasers to replace CNC engraving machines for the aforementioned processing steps, it was found that nanosecond green light, picosecond green light, and picosecond infrared galvanometer processing technologies can perform processes such as cutting, drilling, engraving, milling, grooving, internal and external grinding, notching, routing, and chamfering on glass, but cannot perform polishing efficiently. Furthermore, during cutting, the focal point of galvanometer processing needs to be micro-exploded layer by layer from bottom to top, with each layer feeding from a few micrometers to tens of micrometers, resulting in low processing efficiency. Additionally, it generates edge chipping of tens of micrometers, with small and numerous dust particles at the explosion points, affecting processing quality.

[0031] Reference Figure 1 and Figure 2 As shown, this embodiment of the invention discloses a processing device for transparent materials, including a pre-cutting unit and a post-processing unit. The pre-cutting unit includes a pre-cutting laser 11, a hollow PCF optical plate 12, a Bezier cutting head 13, and a galvanometer. The pre-cutting laser 11 emits an ultrafast laser, which is coupled to the Bezier cutting head and the galvanometer via the hollow PCF optical plate 12. The post-processing unit includes a CO2 laser. A light-emitting head is provided on the CO2 laser. The Bezier cutting head 13, the galvanometer, and the light-emitting head are all mounted on a platform capable of vertical and / or horizontal relative motion with the workpiece. With this optimized design, the pre-cutting laser 11, in conjunction with the Bezier cutting head 13, can achieve rapid cutting, and dust-free separation is achieved through CO2 laser dicing. The pre-cutting laser 11, in conjunction with the galvanometer, can rapidly perform drilling, engraving, milling, grooving, internal grinding, external grinding, notching, routing, and chamfering. The CO2 laser can also be used for glass polishing. Therefore, the pre-cutting laser 11, in conjunction with the Bezier cutting head 13, galvanometer, and CO2 laser, can achieve 12 processing steps, resulting in higher efficiency and lower processing costs for the workpiece. Furthermore, using a hollow PCF optical plate 12 to transmit the laser makes the optical path more stable, and the sealed structure is unaffected by dust, changing the situation where the traditional exposed optical path is contaminated by dust, thus affecting equipment stability. Moreover, the use of the hollow PCF optical plate 12 allows the Bezier cutting head 13 and galvanometer to move rapidly in space, greatly improving movement speed and processing efficiency.

[0032] Specifically, the pre-cut laser 11 is a picosecond laser or a femtosecond laser. Preferably, the pre-cut laser 11 is a picosecond laser, which, compared to a femtosecond laser, has a wider pulse width, lower peak power, narrower spectral dispersion, smaller pulse variation, and transmits more energy with a more stable pulse width. Preferably, the picosecond laser is a picosecond infrared laser.

[0033] Because single hollow PCF fibers are difficult to couple, and the laser beam direction fluctuates within a certain range, long-term laser use may damage the PCF edges, leading to a decline in PCF transmission efficiency and other performance characteristics. To address this issue, a hollow PCF optical plate is used instead of a single hollow PCF fiber. This optical plate consists of 2-100 hollow fibers arranged in a 1×2 to 10×10 fiber array. The optical plate is moved two-dimensionally to switch the single hollow PCF fiber used for laser coupling. The lifetime is increased by 2-100 times compared to a single PCF fiber, and the fiber cross-section is increased by 2-100 times, making coupling easier.

[0034] The aforementioned pre-cut laser 11 is an integrated laser. Its optical components, control circuits, and mechanical parts are integrated together, resulting in a compact size and stable operation.

[0035] The wavelength of the pre-cut laser 11 is 1064 nm. The spot size is 1.0 mm. The beam quality factor M2 is less than 1.3. The emitted laser from the pre-cut laser 11 is vertically polarized.

[0036] In this embodiment of the invention, to save equipment space and cost, only one pre-cut laser 11 is used to operate the Bezier cutting head 13 and the galvanometer. To couple the laser emitted by the pre-cut laser 11 to both the Bezier cutting head 13 and the galvanometer, a coupling module can be provided. The coupling module includes a laser polarization controller 21, a polarization beam splitter (PBS) 22, a first coupling lens 23, and a second coupling lens 24. The laser polarization controller 21 and PBS 22 are sequentially arranged in the output optical path of the pre-cut laser 11. The first coupling lens 23 and the second coupling lens 24 are respectively arranged in the reflection and transmission optical paths of the PBS 22. The laser polarization controller 21 polarizes the laser emitted from the pre-cut laser 11, making it horizontally or vertically polarized. For ease of explanation, horizontal polarization is considered to be perpendicular to the plane of the paper, and vertical polarization is considered to be parallel to the plane of the paper. The PBS 22, i.e., a polarization beam splitter, reflects or transmits polarized light. For example, when the laser is horizontally polarized, the PBS 22 reflects the laser; when the laser is vertically polarized, the PBS 22 transmits the laser. The reflected or transmitted laser light enters its corresponding coupling lens, and the coupling lens couples the laser light into the hollow PCF optical plate 12.

[0037] In order to achieve coupling between the coupling lens and the hollow PCF optical plate 12, the starting point of the hollow PCF optical plate 12 is located at the rear focal point of the coupling lens.

[0038] To achieve coupling between the hollow PCF optical plate 12, the Bezier cutting head 13, and the galvanometer, collimating lenses are respectively placed between the hollow PCF optical plate 12 and the Bezier cutting head 13, and between the hollow PCF optical plate 12 and the galvanometer. The endpoint of the hollow PCF optical plate 12 is located at the front focal point of the collimating lens.

[0039] To enable plug-and-play functionality and rapid maintenance and replacement of the hollow PCF optical board 12, a QBH standard connector can be installed at the light output port of the hollow PCF optical board 12.

[0040] The laser polarization controller 21 described above is either a half-wave plate or an electro-optic modulator. When the laser polarization controller 21 is a half-wave plate, the angle between the optical axis of the half-wave plate and the polarization direction at the laser exit is 45°, changing the laser polarization by 90°; when the angle between the optical axis of the half-wave plate and the polarization direction at the laser exit is adjusted to 0°, the laser polarization direction remains unchanged. When the laser polarization controller 21 is an electro-optic modulator, the polarization direction can be changed by adjusting the voltage. For example, when the voltage of the electro-optic modulator is 0 V, the original polarization direction of the laser is not changed.

[0041] The aforementioned platform includes a Y-axis 16, an X-axis 15, and a Z-axis 14. The X-axis 15 and Y-axis 16 work together to form planar motion, resulting in lighter moving parts and further improving processing speed. The Z-axis 14 is mounted on the X-axis 15. The Bezier cutting head 13, galvanometer, and output head are mounted on the Z-axis 14. In practical use, the Bezier cutting head 13, galvanometer, and output head can be mounted on the same platform or on different platforms.

[0042] When cutting the workpiece, the laser is emitted through the optical path of the Bezier cutting head 13.

[0043] Specifically, in some preferred embodiments, the laser beam is converted from vertical to horizontal polarization by a laser polarization controller 21, and then reflected by a PBS 22 to a coupling lens 23. The coupling lens 23 is a 30 mm focal length aspherical quartz glass mirror. The coupling lens 23 focuses the laser beam diameter to within 53 μm and couples it to a hollow PCF optical plate 12 with a core diameter of 55 μm. The starting point of the hollow PCF optical plate 12 is located at the rear focal point of the coupling lens 23, and the ending point is located at the front focal point of the collimating lens. The length of the hollow PCF optical plate 12 is 2 m or 5 m. The collimating lens is a 300 mm focal length quartz glass lens. The collimating lens collimates the laser beam into a parallel beam with a diameter of 9.6 mm. After passing through the Bezier cutter 13, this parallel beam has a Bezier beam length of 4.5 mm, which is capable of cutting through 4 mm thick glass in one stroke. In addition, by adjusting the position of the focus and processing from bottom to top multiple times, it is possible to cut through 8 mm glass in two cuts, 12 mm glass in three cuts, and so on.

[0044] The pre-cutting laser 11 described above has a power of 10-75 W. When cutting 4 mm glass, it uses a frequency of 10 kHz-75 kHz, a spot pitch of 4 μm, and a pre-cutting speed range of 40 mm / s to 300 mm / s. This is significantly higher than the cutting efficiency of a green nanosecond galvanometer. For 1 mm, 2 mm, and 5 mm glass, the equivalent processing speeds for drilling with a green nanosecond galvanometer are 16 mm / s, 8 mm / s, and 3 mm / s, respectively. After pre-cutting, dust-free separation is achieved by laser cleaving using a CO2 laser.

[0045] When drilling, engraving, milling, grooving, grinding the inner and outer edges, removing defects, routing, or chamfering the workpiece, the laser is emitted through the optical path of the galvanometer.

[0046] Specifically, in some preferred embodiments, the laser beam, after passing through the laser polarization controller 21, maintains its vertical polarization and is transmitted to the coupling lens 24 after passing through the PBS 22. The coupling lens 24 is a 30 mm focal length aspherical quartz glass mirror. The coupling lens 24 focuses the diameter of the laser beam to within 53 μm and couples it to a hollow PCF optical plate 12 with a core diameter of 55 μm. The starting point of the hollow PCF optical plate 12 is located at the rear focal point of the coupling lens 24, and the ending point of the hollow PCF optical plate 12 is located at the front focal point of another collimating lens. The length of the hollow PCF optical plate 12 is 2 m or 5 m. The collimating lens is a 200 mm focal length quartz glass lens. The collimating lens collimates the laser beam into a parallel beam with a diameter of 6.4 mm. This parallel beam enters the galvanometer and, after passing through the 100 mm focal length field mirror, becomes a spot with a diameter of 21 μm. The galvanometer deflects at an angular velocity of up to 100 rad / s, with a maximum speed of 10 m / s.

[0047] The power of the pre-cut laser 11 is 10-75 W. The single pulse energy is 100 μJ. The repetition rate range is 100 kHz-750 kHz, the pulse overlap rate is 50%, and the processing line speed is 1.050 m / s-7.875 m / s.

[0048] During processing, multiple processing steps can be performed on each layer. For drilling, milling, bottom grooving, internal grinding, external grinding, notching, routing, and chamfering, a bottom-up processing method can be used. For top grooving or top chamfering, a top-up processing method can also be used. If the laser focus is adjusted to the lower, middle, or upper surface of the glass, text can be engraved on the lower, middle, or upper surface respectively.

[0049] When polishing a workpiece, a CO2 laser is used to work on the surface of the workpiece.

[0050] Specifically, after the pre-cutting laser 11 works in conjunction with the Bezier cutting head 13 and the galvanometer, the surface roughness of the workpiece is approximately 1 μm. The cut surface is then irradiated with laser light emitted from a CO2 laser, heating the workpiece at the processing point to 30 K below its boiling point. After the glass surface softens, it flattens under surface tension, transforming the rough surface into a mirror finish.

[0051] This invention discloses a method for processing transparent materials using ultrafast lasers and CO2 lasers transmitted via hollow PCF, comprising the following steps: using a hollow PCF optical plate 12 as a light guide arm, directly coupling a pre-cutting laser 11 to a Bezier cutting head 13 and a galvanometer, and pre-cutting the workpiece, and then using a CO2 laser to separate or polish the pre-cut workpiece.

[0052] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novelty disclosed herein.

Claims

1. An apparatus for laser processing of transparent materials via PCF transmission, characterized in that: The device includes a pre-cut laser, a hollow PCF optical plate, a Bessel cutting head, a galvanometer, and a CO2 laser. The hollow PCF optical plate transmits ultrafast laser light to the Bessel cutting head and the galvanometer. The CO2 laser is equipped with a light output head. The Bessel cutting head, the galvanometer, and the light output head are all mounted on a platform that can generate vertical and / or horizontal relative motion with the workpiece. A coupling module is provided between the pre-cutting laser and the Bezier cutting head, and between the pre-cutting laser and the galvanometer. The coupling module includes a laser polarization controller, a polarization beam splitter, a first coupling lens, and a second coupling lens. The laser polarization controller and the polarization beam splitter are sequentially arranged in the output optical path of the pre-cut laser. The first coupling lens and the second coupling lens are respectively arranged in the reflected optical path and the transmitted optical path of the polarization beam splitter. Collimating lenses are respectively installed between the hollow PCF optical plate and the Bezier cutting head, and between the hollow PCF optical plate and the galvanometer. The starting points of the two hollow PCF optical plates are located at the rear focal points of coupling lens one and coupling lens two, respectively, and the ending points are located at the front focal point of a collimating lens, respectively. The hollow PCF optical plate includes 2-100 hollow PCFs for laser coupling and can be switched from one to another.

2. The apparatus for processing transparent materials via PCF transmission according to claim 1, characterized in that: The hollow PCF optical plate has a QBH standard connector at its light outlet, and the end of the optical fiber is located at the focal point in front of the collimating lens.

3. The apparatus for processing transparent materials via PCF laser transmission according to claim 1, characterized in that: The laser polarization controller is a half-wave plate or an electro-optic modulator.

4. The apparatus for processing transparent materials via PCF laser transmission according to claim 1, characterized in that: The pre-cut laser is a picosecond laser or a femtosecond laser.

5. The apparatus for processing transparent materials via PCF transmission according to claim 4, characterized in that: The picosecond laser has a wavelength of 1064 nm, a spot size of 1.0 mm, a beam quality factor M2 of less than 1.3, and the polarization direction of the emitted laser is vertical polarization.

6. The apparatus for processing transparent materials via PCF laser transmission according to claim 1, characterized in that: The hollow PCF is of the Kagome type.

7. A method for processing transparent materials using a PCF-transmitted laser via the device described in claim 1, characterized in that: Using a hollow PCF optical plate as a light guide arm, the pre-cutting laser is directly coupled to the Bezier cutting head and pre-cuts the workpiece. Then, the CO2 laser separates or polishes the pre-cut workpiece.

8. A method for processing transparent materials using a PCF-transmitted laser via the device described in claim 1, characterized in that: Using a hollow PCF optical plate as a light guide arm, the pre-cut laser is directly coupled to the galvanometer to perform drilling, engraving, milling, grooving, internal grinding, external grinding, notching, routing, and chamfering on the workpiece.

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