JP2009039732A - Laser machining apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser machining apparatus for irradiating a workpiece with the respective laser beams divided into a plurality of laser beams, which laser machining apparatus has a novel configuration. <P>SOLUTION: The laser machining apparatus includes: a laser source; a lens for converging the laser beam radiated from the laser source; a beam dividing device which is arranged in front of the converging position in the paths of the laser beams converged by the lens, and propagates the converged laser beam along one radiating path directed from outside among a plurality of the radiating paths; optical fibers which are arranged so as to correspond to the respective radiating paths in the beam dividing device, and have their incident ports arranged at the converging position on the radiating path corresponding to them, and radiate the laser beams input from the incident ports from the radiating ports; and a holding stand for holding the workpiece on the position to be irradiated with the laser beams radiated from the respective radiating ports of the optical fibers. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a laser processing apparatus that irradiates a workpiece with each of a plurality of laser beams distributed.

  In an optical system using a carbon dioxide gas laser, in order to increase the use efficiency of a beam, it has been studied and is being put to practical use to process two or four substrates by dividing the beam path into two or four branches. .

  As a deflector that emits an incident laser beam in different directions, an acousto-optic deflector (AOD) is known.

  When a high-frequency electric signal (AC voltage) is applied to the AOD, an ultrasonic coarse / fine wave synchronized with the electric signal is generated in the AOD acousto-optic medium. This dense wave acts as a diffraction grating, and a part of the incident laser beam is Bragg reflected (acousto-optic effect), deflected and emitted.

  The diffraction angle of the laser beam depends on the frequency of the dense wave. The diffraction angle can be continuously changed by continuously changing the frequency of the dense wave. The frequency of the dense wave can be controlled by changing the frequency of the electric signal. In addition, when an electric signal is not applied to AOD, laser beam diffraction does not occur.

  The maximum angle at which the laser beam can be deflected by AOD is, for example, about 8 °. For this reason, when, for example, one AOD is used to deflect laser beams equally in four directions, the angle between adjacent deflected laser beams is as small as about 2 °. In order to separate these deflected laser beams from each other, it is necessary to make the optical path length very long.

  Inventions of various laser devices using AOD have been disclosed (see, for example, Patent Documents 1 and 2).

JP 2004-191880 A JP 2004-106033 A

  An object of the present invention is to provide a laser processing apparatus that can perform processing by irradiating an object to be processed with laser beams distributed to a plurality of paths.

  According to one aspect of the present invention, a laser light source, a lens for condensing a laser beam emitted from the laser light source, and a path of the laser beam condensed by the lens are arranged in front of the condensing position. A beam branching device for propagating the focused laser beam along one outgoing path commanded from the outside among the multiple outgoing paths, and corresponding to each of the multiple outgoing paths of the beam branching apparatus An optical fiber arranged, wherein the optical fiber has an incident port disposed at a converging position of the laser beam on a corresponding emission path, and emits the laser beam incident from the incident port from the output port. And a holder for holding the irradiated object at a position where the laser beam emitted from each emission port of the optical fiber is incident is provided.

  According to the present invention, it is possible to perform processing by irradiating an object to be processed with laser beams distributed to a plurality of paths.

  FIG. 1 is a schematic diagram illustrating a laser processing apparatus according to an embodiment.

  The laser processing apparatus shown in this figure includes a laser light source 1, condensing lenses 2A and 2B, a beam branching device 3, an optical path adjusting mechanism 4, an optical fiber 5, a mask 6, a galvano scanner 7, an imaging lens 8, a stage 9, and The control device 11 is included.

  The laser light source 1 receives a signal transmitted from the control device 10 and emits a laser beam LB. The laser light source 1 is a carbon dioxide laser, for example, and emits a pulsed laser beam having a wavelength of 9.4 μm or 10.6 μm.

  The laser beam LB emitted from the laser light source enters the condensing lens 2A and is condensed. The condenser lens 2A is made of, for example, ZnSe (zinc selenium), Ge (germanium), or the like.

  The laser beam LB emitted from the condenser lens 2A is distributed to a plurality of paths by the beam branching device 3. In the embodiment, the laser beam LB is distributed to four paths. The four laser beams thus distributed are referred to as laser beam LB1, laser beam LB2, laser beam LB3, and laser beam LB4, respectively.

  An AOD or an acousto-optic modulator (AOM) is used as the beam splitter 3. In the embodiment, the laser beam is distributed using AOD. The distribution path is set by adjusting a high-frequency electric signal applied to the AOD. Ge is used as the material of the AOD crystal.

  Please refer to FIG. FIG. 2 is a schematic view of the vicinity of the beam splitter 3 and the optical path adjustment mechanism 4. The laser beams LB <b> 1 to LB <b> 4 distributed by the beam splitter 3 are incident on the optical path adjustment mechanism 4. The optical path adjustment mechanism 4 has a configuration in which a plurality of reflection mirrors are arranged on the optical path so that the laser beams LB1 to LB4 can be folded back (in the figure, two reflection mirrors are used). As the reflection mirror, a gold coated copper mirror or a dielectric multilayer coated copper mirror is used.

  By providing the optical path adjusting mechanism 4, the optical path length of the laser beam can be increased in a space-saving manner, and the interval between adjacent laser beams can be increased. By widening the interval between adjacent laser beams, each of the laser beams LB1 to LB4 can be made incident on the optical fiber 5 independently. The optical path adjustment mechanism 4 may include more reflection mirrors.

  Returning to FIG. 1, the description will be continued. The laser beams LB1 to LB4 emitted from the optical path adjusting mechanism 4 are incident on the optical fibers 5 arranged corresponding to the respective paths. The laser beams LB1 to LB4 are condensed by the condenser lens 2A. In order for the condensed laser beams LB1 to LB4 to enter the optical fiber 5 without loss, it is a condition that each beam diameter is smaller than the entrance at the position of the entrance of the optical fiber 5 (however, Since the power of the Gaussian beam decreases toward the outside of the beam, it can be said that it is acceptable if (incident aperture diameter) / (incident aperture beam diameter) is about 90%. If this condition is satisfied, the position of the entrance of the optical fiber 5 may be moved back and forth on the optical path.

  Please refer to FIG. FIG. 3 is a cross-sectional view of the optical fiber 5. As the optical fiber 5, for example, a hollow fiber manufactured by Hitachi Cable is used. The hollow fiber has a cylindrical structure in which a hollow region 5a, a transparent dielectric layer 5b, a metal (such as silver) layer 5c, a quartz glass layer 5d, and a polyimide protective layer 5e are sequentially laminated from the center of the cross section toward the outside. For example, the size is 2 m in length, the diameter (inner diameter) of the hollow region is 700 μm, and the outer diameter is 850 μm.

  The hollow fiber has a high damage threshold on the reflecting surface, is excellent in transmitting a laser beam with high peak power, and has a smaller exit beam divergence angle than a solid optical fiber. Further, since the hollow fiber itself is flexible, the hollow fiber can easily transmit the laser beam to a desired position as compared with the articulated beam transmission system combining the conventional mirror and arm.

  For example, it is assumed that the shortest distance between the entrances of two optical fibers selected arbitrarily among the four optical fibers in the embodiment is d. In that case, the shortest distance between the exit ports of the two selected optical fibers can be made longer than d. In particular, by setting it to 400 times or more, it is possible to transmit a laser beam to a position to be processed without providing a complicated beam transmission system.

  Further, since the laser beam propagating in the hollow fiber is reflected a plurality of times during propagation, the laser beam having a Gaussian distribution of light intensity at the time of incidence is converted into a flat top distribution.

  Returning again to FIG. The laser beams LB1 to LB4 incident on the optical fiber 5 propagate and exit the optical fiber 5 while being reflected a plurality of times by the reflection (metal) layer. A condensing lens 2B (the material is the same as 2A) is disposed at the exit of the optical fiber 5. The laser beams LB1 to LB4 emitted from the optical fiber 5 are condensed by the condenser lens 2B.

  Please refer to FIG. FIG. 4 is a schematic diagram of an apparatus configuration from the optical fiber 5 to the workpiece 10 and a laser beam. The laser beams LB1 to LB4 emitted from the optical fiber 5 are condensed by the condenser lens 2B and enter the mask 6. Beryllium copper or tungsten is used as the material of the mask 6. The mask 6 includes a light transmitting area and a light shielding area. The laser beams LB <b> 1 to LB <b> 4 are shaped in cross-section by passing through the light transmitting region of the mask 6.

  The laser beams LB <b> 1 to LB <b> 4 that have passed through the light transmitting region of the mask 6 enter the galvano scanner 7. The galvano scanner 7 includes a pair of swingable reflecting mirrors and scans the laser beams LB1 to LB4 in a two-dimensional direction.

  The laser beams LB <b> 1 to LB <b> 4 scanned by the galvano scanner 7 pass through the imaging lens 8 and irradiate the workpiece 10 held on the stage 9. The imaging lens 8 forms an image of the translucent region of the mask 6 on the surface of the workpiece 10. The imaging lens 8 is an fθ (theta) lens, and the material thereof is the same as that of the condenser lens 2A.

  Since the light intensity distribution of the laser beams LB1 to LB4 is a flat top, the beam cut out by the mask 6 is also a flat top. Therefore, even when a mask having a complicated shape is used, a laser beam having a beam cross section with little bias in the light intensity distribution can be transferred to the workpiece 10.

  The features of the embodiment having the above-described configuration will be described with reference to FIG. FIG. 5A is a schematic diagram illustrating a path of a laser beam according to a comparative example. FIG. 5B is a schematic diagram illustrating a path of a laser beam according to an embodiment. Note that the optical path adjustment mechanism 4 is omitted for the sake of simplicity.

  In order for the laser beams LB1 to LB4 to be used effectively in processing, the respective beams do not have overlapping portions at the entrance position of the optical fiber, and the beam diameter is narrower than the diameter of the opening portion of the optical fiber. Need to be.

  In the comparative example, the condenser lens 2A is not disposed in front of the optical fiber 5 in the laser beam path. As described in the background art section, the maximum angle at which the beam splitter 3 using AOD can split the laser beam is, for example, about 8 °. The laser beam LB0 that has traveled straight through the beam splitter 3 is absorbed by the damper 12 without being used for processing. When the four laser beams branched at an equal angle by the beam branching device 3 are laser beams LB1 to LB4, the angle difference between adjacent laser beams is only 2 °. Therefore, as shown in FIG. 5A, the overlapping portion C between the laser beams becomes longer.

  In order to separate the laser beams from each other and enter the optical fiber 5 without using a condensing lens, a very large space for the path of the laser beam is taken, or a number of reflecting mirrors are arranged three-dimensionally. Since there is only a method of increasing the optical path length l1 from the deflection point of the beam branching device 3 to the optical fiber 5, it is difficult to realize the device.

  Further, when the condensing lens is not arranged before the laser beams LB1 to LB4 enter the optical fiber 5, the beam is not narrowed. Therefore, when laser beams LB1 to LB4 having a beam diameter larger than the aperture diameter of the optical fiber 5 are made incident on the optical fiber 5 as shown in FIG. 5A, there is a problem that the beam loss is large.

  On the other hand, in the embodiment, as shown in FIG. 5B, since the laser beam LB is condensed by the condenser lens 2A before entering the beam branching device 3, the branched laser beams LB1 to LB4 are mutually separated at a short distance. It is possible to enter the optical fiber 5 by completely separating them. At this time, if the optical path length from the deflection point of the beam branching device 3 to the optical fiber 5 is l2, l2 << l1. As a result, the apparatus can be miniaturized or there is no need to arrange a complicated reflecting mirror structure.

  Furthermore, there are the following merits by placing the condenser lens 2A in front of the beam branching device 3.

  When the focused laser beam is incident on the beam branching device 3, the beam diameter in the beam branching device 3 is reduced, so that the polarization switching time can be shortened.

  In order to make each laser beam incident on the optical fiber without loss, it is necessary to narrow the beam with a condenser lens. When the condensing lens is arranged after the beam branching device 3, the same number as the number of fibers is necessary, but when it is arranged before the beam branching device 3, one is sufficient.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. For example, when a laser other than a carbon dioxide laser is used as the laser light source, application is possible if an optical fiber corresponding to the laser is used.

  It will be apparent to those skilled in the art that other various modifications, improvements, combinations, and the like are possible.

FIG. 1 is a schematic view showing a laser processing apparatus in the embodiment. FIG. 2 is a schematic view of the vicinity of the beam splitter 3 and the optical path adjustment mechanism 4. FIG. 3 is a cross-sectional view of the optical fiber 5. FIG. 4 is a schematic diagram of an apparatus configuration from the optical fiber 5 to the workpiece 10 and a laser beam. FIG. 5A is a schematic diagram illustrating a path of a laser beam according to a comparative example, and FIG. 5B is a schematic diagram illustrating a path of a laser beam according to an example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser light source 2A, 2B Condensing lens 3 Beam branching device 4 Optical path adjustment mechanism 5 Optical fiber 5a Hollow area 5b Transparent dielectric layer 5c Metal layer 5d Quartz glass 5e Polyimide protective layer 6 Mask 7 Galvano scanner 8 Imaging lens 9 Stage 10 Workpiece 11 Control device 12 Damper C Overlapping portion LB, LB1, LB2, LB3, LB4 Laser beam

Claims (3)

A laser light source;
A lens for condensing a laser beam emitted from the laser light source;
Among the laser beam paths focused by the lens, the laser beam is arranged in front of the focusing position, and the focused laser beam is sent along one emission path commanded from the outside among the plurality of emission paths. A beam splitter to propagate;
An optical fiber disposed corresponding to each of a plurality of exit paths of the beam splitter, wherein an entrance of the optical fiber is disposed at a condensing position of a laser beam on the corresponding exit path, and the entrance The optical fiber emitting the laser beam incident from the exit from the exit; and
The laser processing apparatus which has a holding stand which hold | maintains a to-be-irradiated object in the position into which the laser beam radiate | emitted from each output port of the said optical fiber injects.   2. The laser according to claim 1, wherein the shortest distance between the exit ports of any two optical fibers selected from the plurality of optical fibers is 400 times or more the shortest distance between the entrance ports of any two optical fibers. Processing equipment.   The laser beam machine according to claim 1, wherein the beam branching device is an acousto-optic deflector.

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