JP2006007279A - Laser machining apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high precision laser machining apparatus, which is miniaturized and has a light weight by preventing a transfer stage of a material to be worked from getting gigantic. <P>SOLUTION: In this laser machining apparatus which irradiates the laser beam generated by a laser generator 1 to a designated point of the material 3 and machines the material by moving the irradiation point, the laser machining apparatus is characterized in that a part or the whole of the laser generator 1 is installed on transfer members 40, 50, 60 movable to the material to be worked 3. As a part or the whole of the laser generator is installed on the transfer member movable to the material to be worked, a stroke of the transfer member has such a size as to cover only the size of the material so that it can prevent the transfer member from getting gigantic and improve positioning accuracy in transferring. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a laser processing apparatus that irradiates a predetermined part of a workpiece with a laser generated from a laser generator and moves the irradiated part to process the workpiece.

  Conventional laser processing apparatuses have fixed a laser generator to a vibration isolation table, moved a non-processed object, and moved a laser irradiation part (for example, refer patent document 1).

However, the conventional laser processing apparatus has a problem that the moving stage of the workpiece becomes heavy and the entire laser processing apparatus becomes heavy and long. In other words, in order to place the workpiece on the moving stage and scan the entire area of the workpiece, there is a moving stage that precisely combines ultra-precise X-axis and Y-axis stages with long strokes. It was necessary. Even if ultra-precise X-axis and Y-axis stages are combined, the stroke is large and the stage is heavy, so it is difficult to move and position with high accuracy, making it difficult to increase machining accuracy. In addition, since the laser generators used in the conventional laser processing apparatus have large external dimensions and weight and are fixedly mounted on the vibration isolating table, the increase in the overall thickness of the laser processing apparatus has become a problem. Furthermore, laser generators used in conventional laser processing apparatuses require cooling of optical components, and there is a problem in that processing accuracy is reduced due to vibration caused by cooling.
JP 2003-340588 A

  As described above, the conventional laser processing apparatus has a problem that the moving stage of the workpiece becomes heavy and the entire laser processing apparatus becomes heavy and long. In addition, because of the increased length and length, high-precision and high-speed positioning could not be performed. In addition, the external dimensions and weight of the laser generator are large, and increasing the overall thickness of the laser processing apparatus has become a problem.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a high-precision laser processing apparatus that prevents a moving stage of a workpiece from becoming heavy and large, and is lightweight and downsized.

  The laser processing apparatus of the present invention irradiates a predetermined part of a workpiece with a laser generated from a laser generator, and moves the irradiation part to process the workpiece. A part or all of the vessel is installed on a moving member that can move relative to the workpiece.

  Since part or all of the laser generator is installed on a movable member that can move with respect to the workpiece, the stroke of the movable member only needs to cover the size of the workpiece, and the moving member is prevented from becoming heavy and heavy. Therefore, the moving positioning accuracy can be increased.

  The laser generator may generate a pulse laser having a pulse width of 10 fs to 20 ps and a repetition frequency of 100 kHz to 10 MHz.

  Since it is a short light pulse with a pulse width of 20 ps or less, the workpiece can be heat-insulated and ultrafine processed.

  The laser generator may include a fiber laser oscillator.

  By making the fiber into a loop shape, the oscillator can be made smaller, and the laser generator can be reduced in weight and size. If the laser generator can be reduced in weight and size, the rigidity of the moving stage can be lowered accordingly, and the overall thickness of the laser processing apparatus can be prevented from being increased. Further, the laser output from the oscillator can be propagated in the fiber without being propagated in the air, and the workpiece can be irradiated with the laser stably. Further, the moving speed and accuracy of movement can be increased by moving the lightweight laser generator by the moving stage.

  The laser generator may further include a fiber amplifier that amplifies the laser output from the fiber laser oscillator.

  The pulse energy can be increased while reducing the weight and size of the laser generator. Further, it has excellent connectivity with a fiber laser oscillator, and the laser output from the oscillator can be propagated through the fiber without being propagated in the air, so that the workpiece can be irradiated with the laser stably. In addition, it is not necessary to forcibly cool the laser generator, and the size and weight can be reduced accordingly, and even if it is installed on a moving stage, there is no vibration and ultra-precision machining can be performed.

  The fiber laser oscillator may include a fiber doped with at least erbium or yttrium as a laser medium.

  The oscillation wavelength is 1.5 μm when erbium is doped, and 1.0 μm when yttrium is doped. When the workpiece is a transparent material such as glass, only the focused irradiation point can be processed.

  The fiber amplifier may include a fiber doped with at least erbium or yttrium as a laser medium.

  Pulse energy from a fiber laser oscillator having a fiber doped with erbium or yttrium as the laser medium can be increased.

  The moving member may be a moving stage that moves in at least two of the X-axis direction, the Y-axis direction, and the Z-axis direction.

  The stroke in the X-axis direction and / or the Y-axis direction of the moving stage only needs to cover the size of the workpiece, and a large workpiece can be machined while preventing the moving stage from becoming heavy and long.

  The laser generator may be configured such that an oscillation module including the fiber laser oscillator and an amplification module including the fiber amplifier are connected by a fiber, and the amplification module is installed on the moving stage.

  By installing only the amplification module on the moving stage, the rigidity of the moving stage can be further reduced, and the laser processing apparatus can be further reduced in size and weight. In addition, the moving speed and the moving accuracy can be increased by moving the lightweight amplification module by the moving stage. Further, since the laser from the oscillation module is amplified by the amplification module and irradiated to the workpiece, the fiber only needs to be able to propagate the laser before amplification, and there is no problem of optical damage, and a fiber having a small core diameter or a single mode fiber is used. Can be used. A fiber having a small core diameter has a small propagation loss even when the bending radius is small, and is flexible, so that the amplification module can be moved in a fine and complicated manner.

  The fiber is preferably a photonic crystal fiber.

  Even if the bending radius is small, the waveform of the laser pulse propagating inside does not collapse, so even if only the amplification module is placed on the moving stage and moved, the pulse width from the amplification module is 10 fs to 20 ps, and the repetition frequency is 100 kHz to 10 MHz. The pulse laser can be emitted.

  Since part or all of the laser generator is installed on a movable stage that can move relative to the workpiece, the stroke of the movable stage only needs to cover the size of the workpiece, preventing the moving stage from becoming too heavy can do.

  By making the laser generator an oscillation module including a fiber laser oscillator and an amplification module including a fiber amplifier connected by a fiber, only the amplification module is installed on the movement stage, thereby further reducing the rigidity of the movement stage. Thus, the laser processing apparatus can be further reduced in size and weight.

  It is possible to increase the moving speed and the moving accuracy by reducing the weight of the moving stage by shortening the stroke of the moving stage and by reducing the weight of the laser generator installed on the moving stage or a part thereof.

  The best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a laser processing apparatus according to the present invention, and FIG. 2 is a view taken in the direction of the arrow in FIG. FIG. 3 is a schematic configuration diagram of the laser generator 1.

  The laser processing apparatus largely includes a laser generator 1 and a processing table 2. The laser generator 1 includes an oscillation module 10 including a fiber laser oscillator 11 and an amplification module including a fiber amplifier 21, as will be described in detail later. 20 are connected by a fiber 30.

  The lower part of the processing table 2 has a structure in which, for example, a granite surface plate 70 is placed on four leg portions 90 via air springs 80, for example. Since the air spring 80 is interposed between the leg portion 90 and the surface plate 70, vibration from the floor is not transmitted to the surface plate 80, and precise machining can be performed. The surface plate 70 has a pedestal 71 extending in the X-axis direction (perpendicular to the paper surface of FIG. 1) whose left and right are raised one step, and a portal-shaped X-axis direction moving stage 50 is placed on the pedestal 71. A sliding surface of a side guide 72 fixed to the pedestal 71, a sliding surface of the pedestal 71, and an air slider 53 are attached so as to be slidable. The sliding is performed by a linear motor including a coil 54 and a permanent magnet 55. A Y-axis direction moving stage 40 is slidably mounted on the X-axis direction moving stage 50 via a fixed guide 43 and a moving guide 41 fixed to the X-axis direction moving stage 50. The sliding is performed by a linear motor including a coil 44 and a permanent magnet 45. The upper end of the fixed guide 61 of the Z-axis direction moving stage 60 is attached to the side surface (see FIG. 2) of the Y-axis direction moving stage 40, and the moving guide 62 is slidably attached on the fixed guide 61. .

  The workpiece 3 is placed on the surface plate 70 of the processing table 2 via the workpiece fixing base 73.

  The oscillation module 10 of the laser generator 1 is placed, for example, on the floor next to the processing table 2 so that the amplification module 20 emits the laser beam downward (−Z direction) to the Z-axis direction moving stage 60 of the processing table 2. Is attached. Therefore, the laser emitted downward from the amplification module 20 is scanned on the workpiece 3 in the X-axis, Y-axis, and Z-axis directions. In addition, the scanning is performed in the X-axis direction and the Y-axis direction, and the movement of the X-axis direction moving stage 50 and the Y-axis direction moving stage 40 is performed by a linear motor via a linear guide and / or an air slider. Even if it becomes, movement is performed at high speed and with high accuracy. Furthermore, since the workpiece 3 is fixed, the movement strokes of the X-axis direction moving stage 50 and the Y-axis direction moving stage 40 may be about the size of the workpiece 3, and it is small and lightweight to be attached. Since the amplification module 20 can be moved at high speed and with high accuracy, it is possible to prevent the processing table 2 including the X-axis direction moving stage 50 and the Y-axis direction moving stage 40 from becoming heavy and large.

  The laser generator 1 has an oscillation module 10, a fiber 30, and an amplification module 20, as shown in FIG. The oscillation module 10 receives a fiber laser oscillator 11, a fiber stretcher 12 that receives a short light pulse generated from the fiber laser oscillator 11 and outputs a stretched short light pulse, and receives the stretched short light pulse. Housed in the oscillation module housing 15 are a pulse thinning device 13 that thins out the pulses and a fiber preamplifier 14 that receives the short light pulses that have been thinned out and output the amplified short light pulses. Become. The amplification module 20 receives a short light pulse amplified by the preamplifier 14 and further amplifies it, a lens 22 for collimating the short light pulse amplified by the fiber main amplifier 21, and a polarization control. The quarter-wave plate 23, the isolator 24, the compressor 25 that receives the amplified short light pulse and outputs the compressed short light pulse, the shutter 26, and the laser beam on the workpiece 3. The condenser lens 27 to be irradiated is housed in the amplification module housing 28. The fiber used for the fiber laser oscillator 11, the fiber stretcher 12, the fiber preamplifier 14, and the fiber main amplifier 21 and the fiber 30 are preferably single mode fibers. A single mode laser with good beam quality can be emitted from the amplification module and fine processing can be performed. Further, the fiber used for the fiber laser oscillator 11, the fiber stretcher 12, the fiber preamplifier 14, and the fiber main amplifier 21 and the fiber 30 are preferably polarization maintaining fibers. There is no need to fix the fiber laser oscillator 11, the fiber stretcher 12, the fiber preamplifier 14, the fiber main amplifier 21, and the fiber 30 or hold them in a loop shape to stabilize the laser.

  For example, the fiber laser oscillator 11 has a pulse width of 1 to 50 ps using an Er-doped fiber as a gain medium, an average output power of 0.1 to 50 mW, an oscillation wavelength of 1.55 μm, and a repetition frequency of 1 to 100 MHz. Passive mode-locked fiber lasers that generate optical pulses can be used. The fiber laser oscillator 11 preferably has a fiber pigtail that outputs a short optical pulse. The generated short light pulse can be incident on the fiber stretcher 12 without propagating in the air.

  As the fiber stretcher 12, a dispersion compensating fiber or a chirped fiber Bragg grating can be used. The dispersion compensating fiber extends the pulse width by chromatic dispersion. The chromatic dispersion is obtained by adding the waveguide dispersion to the material dispersion, and can be easily controlled by appropriately selecting the material, the cutoff wavelength, and the relative refractive index difference between the core and the clad. The pulse stretching rate is determined by chromatic dispersion and length (optical path length), and it is easy to stretch 100 to 1000 times with a dispersion compensating fiber having a length of 100 m. The chirped fiber Bragg grating can be formed, for example, by photolithography using a 10 cm long chirped phase mask on a Ge-doped fiber. It can be stretched 10,000 times with a 10 cm long chirped fiber Bragg grating.

  As the pulse thinning device 13, a light intensity modulator can be used. Examples of the light intensity modulator include an electro-optic light modulator, an acousto-optic light modulator, a magneto-optic light modulator, and a stress-optic light modulator, but are not particularly limited. A short optical pulse with a repetition frequency of 1 to 100 MHz from the fiber laser oscillator 11 is thinned out by the pulse thinning device 13 and converted into a repetition frequency of 5 to 500 KHz. When the pulse is thinned, the average power is naturally reduced by the thinned amount. For example, when a short light pulse with an average power of 1 mW and a repetition frequency of 1 MHz is thinned out to a repetition frequency of 5 KHz, the average power is reduced to 5 μW. The pulse thinning device 13 is used because the fiber amplifiers 14 and 21 receive and amplify short light pulses with a pulse interval, so that the gain per pulse is increased and short light pulses with high peak power are output. Because it can be done.

  The preamplifier 14 is for amplifying the average power reduced to 5 μW to a level of 1 mW, and can be achieved by doping a single mode fiber core with Er. The pumping is performed, for example, by guiding laser light having a wavelength of 1.48 μm from the laser diode 142 to the core via the wavelength division multiplex fiber coupler 143.

  The main amplifier 21 is preferably a multimode double clad fiber 211 having a core diameter of 10 to 50 μm. Even if the peak power per pulse in the subsequent stage of the amplifier becomes 1 kW or more, it is possible to prevent the nonlinear phenomenon from occurring. The core is co-doped with Er or Er and Yb. The pumping is preferably so-called side pumping performed by forming a V-groove in the cladding, or cladding pumping performed using a star coupler. A lot of pumping power can be input. As the pump light source 212, a multimode laser diode having an oscillation wavelength band of 915 nm, 945 nm, or 975 nm can be used. If 211 is replaced with a single-mode double-clad fiber instead of a multi-mode double-clad fiber, the amplification factor cannot be increased due to a nonlinear phenomenon, but a single-mode laser with good beam quality can be generated.

  The compressor 25 includes bulk diffraction elements 251 and 252 that do not exhibit a nonlinear phenomenon even with a short optical pulse with a high peak power amplified by the fiber amplifier 21. As the bulk diffraction element, a diffraction grating, a prism, a holographic grating, or the like can be used.

  In this embodiment, the fiber laser oscillator 11 of FIG. 3 uses an Er-doped fiber as a gain medium, has a pulse width of 100 to 1000 fs, an average output power of 10 mW, an oscillation wavelength of 1.56 μm, and a repetition frequency of 40 to 50 MHz. A passive mode-locked fiber laser that repeatedly generates short light pulses was used.

  The fiber stretcher 12 is a polarization maintaining fiber having a wavelength dispersion of 200 ps / nm / km and a length of 100 m.

  The pulse thinning-out device 13 is a waveguide type electro-optic light modulator, and has a Z-cut LiNbO3 crystal and a pulse generator constituting a Mach-Zehnder interferometer. The pulse generator has a function and performance of applying a voltage having a pulse width of 10 to 20 ns and a repetition frequency of 100 kHz to 10 MHz to the LiNbO3 crystal.

  The preamplifier 14 includes a single-mode polarization maintaining fiber 141 having a length of 2.6 m with a core doped with Er, a laser diode 142 as a pump light source, and a wavelength division multiplexing polarization maintaining fiber coupler 143. Yes. The laser diode 142 has a fiber pigtail and generates a single mode laser beam having a wavelength of 1.48 μm and an output of 400 mW.

  The main amplifier 21 has a multi-mode polarization-maintaining double clad fiber 211 having a core diameter of 16 μm and a length of 2.4 m co-doped with Er and Yb, and a laser diode 212. The laser diode 212 generates a multimode laser beam having a wavelength of 975 nm and an output of 4 W. The laser beam generated from the laser diode 212 is collimated by the lens 213 and coupled to the first clad of the double clad fiber 211.

  The compressor 25 includes a pair of diffraction gratings 251 and 252.

  The lens 22 is for collimating a short light pulse emitted from the emission end of the main amplifier 32.

  As the condenser lens 27, a microscope objective lens having a magnification of 50 times was used.

  The dimensions of the oscillation module 10 are 318 mm × 261 mm × 108 mm and the weight is 2300 g. The dimensions of the amplification module 20 are 250 mm × 470 mm × 100 mm and the weight is 1400 g.

  Since the non-processed object 3 of this embodiment is a glass for a large liquid crystal TV having a size of 1870 mm × 2200 mm and a thickness of 1.1 mm, the stroke of the Y-axis direction moving stage 40 is 1900 mm and the X-axis direction moving stage 50 is The stroke was set to 2400 mm.

  The overall dimensions of the laser processing apparatus were 2600 mm × 3700 mm × 1500 mm, and the weight was 2300 kg. In the conventional laser processing apparatus for moving the workpiece, it is expected that the size is at least 3000 to 4000 mm × 4000 to 6000 mm × 1500 mm, and it can be seen that the laser processing apparatus of this example is small.

  The moving speed of the Y-axis direction moving stage 40 and the X-axis direction moving stage 50 was 300 mm / s, and the positioning accuracy was 5 μm. In particular, even if the stroke of the Y-axis direction moving stage 40 is 1900 mm and the stroke of the X-axis direction moving stage 50 is as large as 2400 mm, the positioning accuracy is 5 μm. The weight of the amplification module 20 attached to the moving stage is as light as 1400 g. It is because it was.

  The operation results of the laser generator 1 of the apparatus of this embodiment will be described below. A pulse width of 100 to 1000 fs was stretched by the fiber stretcher 12 to 70 to 250 ps. The repetition frequency of 40 to 50 MHz was converted to 100 kHz to 10 MHz by the pulse thinning device 13. A short light pulse with an average power of 10 mW generated from the fiber laser oscillator 11 was thinned out by the pulse thinning device 13 and decreased to 10 to 20 μW, but was amplified to 20 mW by the preamplifier 14. The short optical pulse amplified to 20 mW by the preamplifier 14 was amplified to 2 W by the main amplifier 21. A short light pulse with a pulse width of 70 to 250 ps and an average power of 2 W emitted from the output end of the main amplifier 21 was compressed by the compressor 23 to emit a short light pulse with a pulse width of 10 fs to 20 ps and an average power of 1 W. That is, a short light pulse having a pulse width of 10 fs to 20 ps, an average power of 1 W, and a repetition frequency of 100 kHz to 10 MHz is condensed and applied to the workpiece 3 from the amplification module 20 attached to the Z-axis direction moving stage 60 of the processing table 2. .

  Although the embodiment of the present invention has been described above, the present invention is not limited to this. For example, an arm that can be moved in three dimensions can be used instead of a stage as the moving member.

It is a schematic block diagram of the laser processing apparatus of Example 1. FIG. FIG. 2 is an arrow diagram of FIG. 1. 1 is a schematic configuration diagram of a laser generator of Example 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ...... Laser generator 3 ... Workpiece 10 ... Oscillation module 11 ... Fiber laser oscillator 14 ... Fiber preamplifier 20 ... Amplifier module 21 ... Fiber main amplifier 30 ... Fibers 40, 50, 60 .... Moving member 40 ... Y-axis direction moving stage 50 ... X-axis direction moving stage 60 ... Z-axis direction moving stage

Claims (9)

In a laser processing apparatus that irradiates a predetermined part of a workpiece with a laser generated from a laser generator and moves the irradiation part to process the workpiece,
A laser processing apparatus, wherein a part or all of the laser generator is installed on a movable member that can move relative to the workpiece.   The laser processing apparatus according to claim 1, wherein the laser generator generates a pulse laser having a pulse width of 10 fs to 20 ps and a repetition frequency of 100 kHz to 10 MHz.   The laser processing apparatus according to claim 2, wherein the laser generator includes a fiber laser oscillator.   The laser processing apparatus according to claim 3, wherein the laser generator further includes a fiber amplifier that amplifies a laser output from the fiber laser oscillator.   5. The laser processing apparatus according to claim 3, wherein the fiber laser oscillator includes a fiber doped with at least erbium or yttrium as a laser medium.   6. The laser processing apparatus according to claim 4, wherein the fiber amplifier includes a fiber doped with at least erbium or yttrium as a laser medium.   The laser processing apparatus according to any one of claims 1 to 6, wherein the moving member is a moving stage that moves in at least two of the X-axis direction, the Y-axis direction, and the Z-axis direction.   The laser generator is characterized in that an oscillation module including the fiber laser oscillator and an amplification module including the fiber amplifier are connected by a fiber, and the amplification module is installed on the moving member. The laser processing apparatus according to any one of 3 to 7.   The laser processing apparatus according to claim 8, wherein the fiber is a photonic crystal fiber.

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