JP2010260063A - Laser beam machining apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam machining apparatus that improves efficiency of utilizing a laser beam. <P>SOLUTION: The laser beam machining apparatus 1 includes a laser beam source 10, a first polarizing beam splitter 14 and a second polarizing beam splitter 15, a first spatial light phase modulator 18 and a second spatial light phase modulator 19, and a condensing lens 40. The first polarizing beam splitter 14 branches the laser beam from the laser beam source 10 into a first polarization component and a second polarization component that is orthogonal to the first polarization component. The first spatial light phase modulator 18 performs phase modulation by receiving the first polarization component and outputs the phase-modulated polarization component as first modulated light, and performs phase modulation by receiving the second polarization component and outputs the phase-modulated second polarization component as second modulated light. The second polarizing beam splitter 15 combines the first second modulated light with the second modulated light. The first and the second spatial light phase modulators 18, 19 are arranged so that the polarization directions coincide with the polarization of the first and the second polarization component respectively. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a laser processing apparatus that performs processing using laser light.

  A laser processing apparatus that collects laser light and irradiates the object to be processed to process the surface or the inside of the object to be processed is widely known, and this type of laser processing apparatus is disclosed in Patent Documents 1 to 5. Has been. In particular, Patent Documents 1 to 3 disclose laser processing apparatuses that focus laser light on a plurality of different processing positions on a processing target. As described above, by condensing the laser beam at a plurality of positions, a plurality of positions on the object to be processed can be processed simultaneously, and the processing time can be shortened. In the laser processing apparatuses described in Patent Documents 1 to 3, in order to condense laser light at a plurality of positions, a spatial light modulator (Spatial Light Modulator: SLM), a birefringent crystal, a diffractive optical element ( Diffractive Optical Element (DOE) is used.

  By the way, a spatial light phase modulator using a liquid crystal as a phase modulation unit has polarization dependency. Therefore, of the laser light incident on the spatial light phase modulator, the polarization component that matches the polarization direction of the spatial light phase modulator can be phase-modulated and the condensing position can be controlled. The polarization component orthogonal to the polarization direction of the modulator cannot be phase-modulated, and the condensing position or condensing shape cannot be controlled. As a result, the polarization component orthogonal to the polarization direction of the spatial light phase modulator cannot be condensed at the same position as the polarization position of the polarization component that matches the polarization direction of the spatial light phase modulator, It will be condensed at different positions as zero order light. As a result, unintended positions are damaged by the 0th-order light. In this regard, Patent Document 5 discloses a laser processing apparatus that removes unnecessary zero-order light by providing a zero-order light shielding plate at the output stage.

JP 2006-68762 A International Publication No. 2005/84874 Pamphlet Japanese Patent No. 3346374 Japanese Patent Laid-Open No. 2004-290985 JP 2001-272636 A

  However, in the laser processing apparatus described in Patent Document 5, the 0th-order light is wasted, and a part of the laser light was wasted.

  Therefore, an object of the present invention is to provide a laser processing apparatus that improves the utilization efficiency of laser light.

  A laser processing apparatus according to the present invention includes: (a) a laser light source that generates laser light; and (b) a laser processing apparatus that collects laser light and irradiates the processing target to process the processing target. A first polarization beam splitter for branching laser light from a laser light source into a first polarization component and a second polarization component having a polarization orthogonal to the polarization of the first polarization component; A first spatial light phase modulator for receiving a single polarization component and performing spatial phase modulation, wherein the polarization direction of the first spatial light phase modulator matches the polarization of the first polarization component And (d) a second spatial light phase modulator that receives the second polarization component and performs spatial phase modulation, the first spatial light phase modulator arranged to The polarization direction of the second spatial light phase modulator matches the polarization of the second polarization component The second spatial light phase modulator arranged in the above manner; and (e) first modulated light and second spatial light phase obtained by phase-modulating the first polarization component by the first spatial light phase modulator. A second polarization beam splitter that combines the second modulated light obtained by phase-modulating the second polarization component by the modulator; and (f) condensing the first and second modulated lights on the workpiece. A condensing lens.

  According to the present invention, the first polarization component and the second polarization component having different polarization directions in the laser beam are branched by the first polarization beam splitter, and two first and second spatial light phase modulations are performed. The first and second polarization components are phase-modulated by using the optical device, and the first and second modulated lights are synthesized by the second polarization beam splitter and irradiated onto the workpiece. Therefore, for example, the zero-order light component for the first spatial light phase modulator is actively used by the second spatial light phase modulator without wasting it, thereby improving the laser light utilization efficiency. be able to.

  At least one of the first and second spatial light phase modulators described above performs phase modulation so that the condensing position of the first modulated light is different from the condensing position of the second modulated light. You may do it. Further, the first and second spatial light phase modulators described above may perform phase modulation so that at least one of the first and second modulated lights is condensed at a plurality of different positions. Good. According to this, simultaneous processing of a plurality of processing positions can be performed.

  Further, at least one of the first and second spatial light phase modulators described above is different in the optical axis direction between the condensing position of the first modulated light and the condensing position of the second modulated light. It may be allowed. According to this, multi-point simultaneous machining at different machining positions in the machining depth direction of the workpiece can be performed.

  Further, at least one of the first and second spatial light phase modulators described above makes the condensing position of the first modulated light different from the condensing position of the second modulated light in the scanning direction. May be. According to this, multi-point simultaneous machining at different machining positions in the machining scanning direction of the workpiece can be performed.

  Further, at least one of the first and second spatial light phase modulators described above scans the condensing position of the first modulated light and the condensing position of the second modulated light in the optical axis direction and scanning. You may make it differ in the direction which cross | intersects a direction. According to this, it is possible to perform multi-point simultaneous machining at different machining positions in the direction intersecting the machining depth direction and the machining scanning direction of the workpiece.

  The laser light source described above emits laser light having random polarization.

  ADVANTAGE OF THE INVENTION According to this invention, the utilization efficiency of a laser beam can be improved in laser processing. As a result, the processing efficiency can be improved.

It is a perspective view which shows the laser processing apparatus which concerns on embodiment of this invention. It is a figure which simplifies and shows the laser processing apparatus of this embodiment. It is a figure which shows the condensing position in the process target object of the laser processing apparatus of this embodiment. It is a figure which shows the condensing position in the process target object of the laser processing apparatus which concerns on the modification of this invention. It is a figure which shows the condensing position with respect to the process target object of the laser processing apparatus which concerns on the modification of this invention. It is a figure which shows the condensing position in the process target object of the laser processing apparatus which concerns on another modification of this invention. It is a figure which shows the condensing position in the process target object of the laser processing apparatus which concerns on another modification of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals.

  FIG. 1 is a perspective view showing a laser processing apparatus according to an embodiment of the present invention, and FIG. 2 is a simplified view of the laser processing apparatus of the present embodiment shown in FIG. Moreover, FIG. 3 is a figure which shows the condensing position with respect to the process target object of the laser processing apparatus of this embodiment. 1 and 2 also show both the object to be processed and the laser beam shown in FIG.

  1 and 2 includes a laser light source 10, a collimating lens 12, first and second polarization beam splitters 14 and 15, first and second prism mirrors 16 and 17, First and second spatial light phase modulators (SLM) 18 and 19, two mirrors 20 and 21, an objective lens 40 (condensing lens), and a stage 42 are provided.

  The laser light source 10 emits divergent light having random polarization. In the following, it is assumed that the laser light source 10 generates laser light including polarization directions D1 and D2 that are orthogonal to each other. The laser light is expanded to a size that allows the first and second spatial light phase modulators 18 and 19 to obtain a sufficient spatial resolution for phase modulation, and then converted into parallel light by the collimator lens 12. 1 is incident on the polarization beam splitter 14.

  The first polarization beam splitter 14 branches the incident laser beam into a first polarization component h1 and a second polarization component h2 having a polarization orthogonal to the polarization of the first polarization component h1. For example, the first polarization beam splitter 14 transmits the first polarization component h1 in the polarization direction D1 of the incident laser light and outputs it in the first direction D11, and the polarization direction orthogonal to the polarization direction D1. The second polarization component h2 of D2 is reflected and output in a second direction D22 that is substantially perpendicular to the first direction D11.

  The first polarization component h 1 that has passed through the first polarization beam splitter 14 is incident on the first spatial light phase modulator 18 via the first prism mirror 16. On the other hand, the second polarization component h 2 reflected from the first polarization beam splitter 14 is turned about 90 degrees by the mirror 20 and output in the first direction D 11, and the second polarization component h 2 is transmitted through the second prism mirror 17 to the second direction. Is incident on the spatial light phase modulator 19. That is, the first polarization component h1 and the second polarization component h2 travel substantially in parallel.

  The first and second spatial light phase modulators 18 and 19 have a plurality of pixels that are two-dimensionally arranged. For example, the incident light is incident according to a hologram such as a Fresnel lens pattern or CGH (Computer Generated Hologram). Spatial phase modulation of the laser beam is performed.

  The first spatial light phase modulator 18 has polarization dependency and has polarization characteristics in a specific direction. For example, the first spatial light phase modulator 18 is arranged to have a polarization direction that matches the polarization direction D1 of the first polarization component h1. As a result, the first spatial light phase modulator 18 performs phase modulation on the first polarization component h1 and outputs the first modulated light hm1. In the first spatial light phase modulator 18, the first modulated light hm1 obtained by phase-modulating the first polarization component h1 is controlled by controlling a hologram (for example, the above-described CGH or Fresnel lens pattern). A hologram reproduction image can be formed by focusing light on the surface of the object 50 and an arbitrary position inside.

  Similarly, the second spatial light phase modulator 19 has polarization dependency and has polarization characteristics in a specific direction. For example, the second spatial light phase modulator 19 is arranged to have a polarization direction that matches the polarization direction D2 of the second polarization component h2. As a result, the second spatial light phase modulator 19 performs phase modulation on the second polarization component h2, and outputs it as the second modulated light hm2. The second spatial light phase modulator 19 controls the second modulated light hm2 obtained by phase-modulating the second polarization component h2 by controlling a hologram (for example, the above-described CGH or Fresnel lens pattern). A hologram reproduction image can be formed by focusing light on the surface of the object 50 and an arbitrary position inside.

  When the polarization direction D2 and the polarization direction of the second spatial light phase modulator 19 are orthogonal to each other, a half-wave plate is disposed before and after the second spatial light phase modulator 19 (for example, a mirror). And a half-wave plate on the optical path between the prism 20 and the prism mirror 17 and on the optical path between the prism mirror 17 and the mirror 21), and the polarization of the second spatial light phase modulator 19 The direction and the polarization direction D2 are made to coincide.

  In the present embodiment, a reflective spatial light phase modulator is exemplified as the first and second spatial light phase modulators 18 and 19, but a transmissive spatial light phase modulator may be used. In this case, it is not necessary to provide the first and second prism mirrors 16 and 17. As the reflective spatial light phase modulator, a liquid crystal spatial light phase modulator LCOS (Liquid Crystal on Silicon) type, an optical address type, or the like is applicable. On the other hand, an LCD (Liquid Crystal Display) type or the like is applicable as the transmissive spatial light phase modulator.

  The first modulated light hm1 output from the first spatial light phase modulator 18 is incident on the second polarization beam splitter 15 via the first prism mirror 16. On the other hand, the second modulated light hm2 output from the second spatial light phase modulator 19 is incident on the mirror 21 via the second prism mirror 17, and is redirected by about 90 degrees by the mirror 21. Is output in the direction opposite to the direction D22 and enters the second polarization beam splitter 15.

  The second polarization beam splitter 15 combines the first modulated light hm1 from the first spatial light phase modulator 18 and the second modulated light hm2 from the second spatial light phase modulator 19. For example, if the polarization direction of the second polarization beam splitter 15 is matched with the polarization direction of the first polarization beam splitter 14, the second polarization beam splitter 15 transmits the first modulated light hm1 and transmits the first modulation light hm1. The second modulated light hm2 is reflected and output in the first direction D11. The first modulated light hm1 and the second modulated light hm2 output from the second polarization beam splitter 15 are incident on the objective lens 40.

  The objective lens 40 collects both the first modulated light hm1 and the second modulated light hm2 on the surface or inside of the workpiece 50 on the stage 42.

  The stage 42 supports the workpiece 50 and is slidable. Accordingly, the first modulated light hm1 and the second modulated light hm2 can be scanned relative to the workpiece 50.

  In this laser processing apparatus 1, the first spatial light phase modulator 18 and the second spatial light phase modulator 19 are used to phase at least one of the first modulated light hm1 and the second modulated light hm2. The modulation is controlled so that the condensing position of the first modulated light hm1 and the condensing position of the second modulated light hm2 are made different in the optical axis Z direction, that is, in the processing depth direction of the workpiece 50.

  For example, the first modulated light hm1 is condensed at the condensing position A by controlling a hologram (for example, a Fresnel lens pattern) supplied to the first spatial light phase modulator 18. Thereafter, the second modulated light hm2 is condensed at the condensing position B by controlling a hologram (for example, a Fresnel lens pattern) supplied to the second spatial light phase modulator 19.

  The condensing position of the second modulated light hm2 is first determined by the second spatial light phase modulator 19, and then the condensing position of the first modulated light hm1 by the first spatial light phase modulator 18. May be determined. Even if the condensing position of the first modulated light hm1 by the first spatial light phase modulator 18 and the condensing position of the second modulated light hm2 by the second spatial light phase modulator 19 are simultaneously performed. Good.

  Thereafter, when the first modulated light hm1 and the second modulated light hm2 are scanned relative to the workpiece 50 by sliding the stage 42, two-point simultaneous machining can be performed continuously. It becomes.

  By the way, in the conventional laser processing method, when laser light including a plurality of different polarized lights is incident on one spatial light phase modulator, unmodulated light whose control position is not controlled, that is, zero-order light is generated. Light has been treated as unwanted light. In particular, in processing using one optical phase modulator for a randomly polarized light source, the polarization component orthogonal to the polarization direction of the optical phase modulator becomes zero-order light. Therefore, for example, as described in Patent Document 5, zero-order light is removed by a zero-order light shielding plate or the like, or the ratio of zero-order light is reduced by increasing the accuracy of the hologram of the spatial light phase modulator. Attempts have been made. Further, after removing a polarization component orthogonal to the polarization direction of the optical phase modulator by the polarization element, a hologram reproduction image (modulated light) and zero-order light are superimposed by superimposing a Fresnel lens on the hologram of the spatial light phase modulator. Attempts have been made to reduce the effects of zero order light. However, it is impossible to completely remove the 0th-order light, and in the conventional laser processing technique, some components of the laser light are wasted.

  However, according to the laser processing apparatus 1 of the present embodiment, the first polarization beam splitter 14 splits the laser light into the first polarization component h1 and the second polarization component h2 whose polarization directions are orthogonal to each other. Phase modulation of the first and second polarization components h1 and h2 is performed using the first and second spatial light phase modulators 18 and 19, respectively, and the first and second modulations are performed by the second polarization beam splitter 15. The light hm1 and hm2 are synthesized and irradiated to the workpiece 50. Therefore, for example, the zero-order light component for the first spatial light phase modulator 18 is actively used by the second spatial light phase modulator 19 without wasting it. Can be improved. As a result, the processing efficiency can be improved by a factor of two.

  The laser processing apparatus 1 according to the first embodiment can reduce zero-order light that is not modulated by the spatial light phase modulator, and can irradiate the workpiece with only the modulated light modulated by the spatial light phase modulator. Therefore, it has a great effect in applications where high-precision machining is performed.

  The present invention is not limited to the above-described embodiment, and various modifications can be made. For example, in the present embodiment, the second modulated light hm2 is condensed at one condensing position B different from the condensing position A of the first modulated light hm1, but the first modulated light hm1 and the second modulated light hm2 The above-described CGH may be used for at least one of the modulated light hm2 and condensed at two or more positions different from the other. Thereby, three or more other points can be simultaneously processed. As a result, the processing efficiency is dramatically improved.

  Further, the condensing position of the first modulated light hm1 and the condensing position of the second modulated light hm2 may be the same. Thereby, one point processing becomes possible.

  In the present embodiment, the condensing position A of the first modulated light hm1 and the condensing position B of the second modulated light hm2 are made different in the optical axis Z direction, but as shown in FIG. It may be different on a plane orthogonal to the axis Z direction.

  For example, as shown in FIG. 5, the condensing position A of the first modulated light hm1 and the condensing position B of the second modulated light hm2 may be different in the scanning direction X. As a result, the number of irradiation points in the scanning direction X can be increased, and an effect of effectively multiplying the repetition frequency of the pulsed laser light can be obtained. For example, when the repetition frequency of the laser light from the laser light source is 1 kHz, the same effect as that obtained when the pulsed laser light having an effective repetition frequency of 2 kHz is irradiated with modulated light and non-modulated light can be obtained.

  Further, as shown in FIG. 6, the condensing position of the pulsed second modulated light hm2 may coincide with the condensing position of the previous pulsed first modulated light hm1. Thereby, the effect of double pulse irradiation can be effectively obtained. Here, there is a processing method in which a workpiece is processed non-thermally by multiphoton absorption or the like by irradiating ultra-short pulse light at short time intervals. Laser-induced plasma is used in processing with this ultrashort pulse light, and the generation efficiency of laser-induced plasma may be improved in order to improve the processing efficiency. In order to improve the generation efficiency of laser-induced plasma, double pulse irradiation is effective. As a result, as shown in FIG. 6, the condensing position of the pulsed second modulated light hm2 and the condensing position of the previous pulsed first modulated light hm1 are made coincident with each other and effectively doubled. By performing pulse irradiation, the generation efficiency of laser-induced plasma can be improved, and as a result, the processing efficiency can be improved.

  Further, as shown in FIG. 7, the condensing position A of the first modulated light hm1 and the condensing position B of the second modulated light hm2 are made different in the optical axis Z direction and the direction Y orthogonal to the scanning direction X. May be. Thereby, two-point simultaneous processing in a plane perpendicular to the laser beam scanning direction X is possible.

  Further, a mechanism (for example, a polarizing plate or a neutral density filter) that adjusts the light amount of each laser beam branched by the beam splitter 14 may be arranged to adjust the light amount to be uniform.

  DESCRIPTION OF SYMBOLS 1 ... Laser processing apparatus, 10 ... Laser light source, 12 ... Collimating lens, 14 ... 1st polarizing beam splitter, 15 ... 2nd polarizing beam splitter, 16 ... 1st prism mirror, 17 ... 2nd prism mirror, DESCRIPTION OF SYMBOLS 18 ... 1st spatial light phase modulator, 19 ... 2nd spatial light phase modulator, 20, 21 ... Mirror, 40 ... Objective lens (condensing lens), 42 ... Stage, 50 ... Processing object.

Claims (7)

In a laser processing apparatus for condensing a laser beam and irradiating the processing object to process the processing object,
A laser light source for generating laser light;
A first polarization beam splitter that branches the laser light from the laser light source into a first polarization component and a second polarization component having a polarization orthogonal to the polarization of the first polarization component;
A first spatial light phase modulator for receiving the first polarization component and performing spatial phase modulation, wherein the polarization direction of the first spatial light phase modulator is the first polarization component The first spatial light phase modulator arranged to match the polarization;
A second spatial light phase modulator for receiving the second polarization component and performing spatial phase modulation, wherein a polarization direction of the second spatial light phase modulator is the second polarization component The second spatial light phase modulator arranged to match the polarization;
A first modulated light obtained by phase-modulating the first polarization component by the first spatial light phase modulator and a phase modulation of the second polarization component by the second spatial light phase modulator. A second polarizing beam splitter for combining the second modulated light;
A condensing lens for condensing the first and second modulated lights on the workpiece;
A laser processing apparatus comprising: At least one of the first and second spatial light phase modulators is phase-modulated so that the condensing position of the first modulated light and the condensing position of the second modulated light are different. Is characterized by
The laser processing apparatus according to claim 1. The first and second spatial light phase modulators perform phase modulation so that at least one of the first and second modulated lights is condensed at a plurality of different positions. To
The laser processing apparatus according to claim 1. At least one of the first and second spatial light phase modulators makes the condensing position of the first modulated light different from the condensing position of the second modulated light in the optical axis direction. It is characterized by
The laser processing apparatus according to claim 2 or 3. At least one of the first and second spatial light phase modulators makes the condensing position of the first modulated light different from the condensing position of the second modulated light in the scanning direction. Characterized by the
The laser processing apparatus according to claim 2 or 3. At least one of the first and second spatial light phase modulators determines the condensing position of the first modulated light and the condensing position of the second modulated light in the optical axis direction and the It is characterized by being different in the direction intersecting the scanning direction,
The laser processing apparatus according to claim 2 or 3.   The laser processing apparatus according to claim 1, wherein the laser light source emits laser light having random polarization.

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