JP2014042916A - Laser processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser apparatus, in which diffraction light of a high order can be blocked by a simple structure when a DOE is used to branch a laser beam.SOLUTION: A laser processing apparatus for processing a work-piece by irradiating the same with a laser beam comprises: a work table 2; a laser beam output section 15 for outputting a laser beam; a DOE 34 for branching the laser beam from the laser beam output section 15 into a plurality of laser beams; a condenser lens 201 for condensing the laser beams from the DOE 34; a shielding plate 202 disposed between the condenser lens 201 and the work table 2 for shielding a laser beam of the DOE 34 at a predetermined or higher order; and a relay lens 203 for condensing the laser beam having passed through the shielding plate 202, on the work-piece.

Description

  The present invention relates to a laser processing apparatus that performs processing by irradiating a workpiece with laser light.

  As a laser processing apparatus, for example, an apparatus disclosed in Patent Document 1 is known. In this type of processing apparatus, a green laser beam having a wavelength of about 532 nm is irradiated onto a workpiece such as a glass substrate. The green laser light is generally transmitted through the glass substrate, but when the laser light is collected and the intensity exceeds a certain threshold value, the glass substrate absorbs the laser light. In such a state, plasma is generated in the condensing part of the laser beam, and thereby the glass substrate is evaporated. Processing such as forming a hole in the glass substrate can be performed using the principle described above.

  In Patent Document 2, a plurality of condensing points are formed on a glass substrate using a diffractive optical element (DOE), and the plurality of condensing points are scanned along a processing line while rotating. It is shown that the substrate is processed.

  In a conventional laser processing apparatus as disclosed in Patent Document 1, a means for deflecting laser light or a means for deflecting and branching laser light is rotated. In such a configuration, the deflection unit or the deflection / branching unit is subject to many restrictions. For example, it is necessary to make the rotational balance of each of the above means good, and it is necessary not to tilt the incident beam so that the deflection angle is not affected. Furthermore, when each means is composed of a plurality of elements, it must be ensured that the positional relationship between the elements does not collapse even if it is rotated at a high speed.

  When DOE as shown in Patent Document 2 is used, it is considered that the above problems can be solved. However, when DOE is used, higher-order diffracted light than the first-order diffracted light that contributes to processing is irradiated to the outside of the processing line. There is a problem that the glass substrate is damaged by this irradiation.

  Therefore, as shown in Patent Document 3, a technique has been proposed in which a light-shielding plate is provided above the workpiece to shield higher-order diffracted light.

JP 2007-118054 A JP 2011-11917 A JP 2008-188653 A

  In the apparatus disclosed in Patent Document 3, a light shielding plate is disposed between the diffraction grating and the work in proximity to the work. However, it is difficult to arrange the light shielding plate close to the work because of the configuration of the apparatus, and the structure may be complicated in order to avoid interference between the work and the light shielding plate.

  An object of the present invention is to enable high-order diffracted light to be shielded with a simple configuration when a DOE is used to split a laser beam.

  A laser processing apparatus according to a first aspect of the present invention is an apparatus that performs processing by irradiating a workpiece with laser light, a work table on which the workpiece is placed, and laser light that outputs laser light. An output unit, a laser beam branching unit that includes a diffractive optical element and branches the laser beam from the laser beam output unit into a plurality of laser beams, and a first focusing unit for focusing the laser beam from the laser beam branching unit And a light shielding plate disposed between the first light condensing means and the work table for shielding higher-order laser light of a predetermined level or more of the diffractive optical element, and condensing the laser light that has passed through the light shielding plate on the workpiece. Second condensing means.

  In this apparatus, the laser beam output from the laser beam output unit is branched by the laser beam branching unit and condensed by the first focusing unit. The laser light from the first condensing means includes high-order laser light, but the high-order laser light is shielded by the light shielding plate. Then, the laser light that has passed through the light shielding plate is condensed on, for example, the surface of the workpiece by the second condensing unit.

  Here, the high-order laser light generated by the diffractive optical element is shielded by the light shielding plate. And since the 2nd condensing means is provided between the light-shielding plate and the to-be-processed object, the freedom degree regarding arrangement | positioning of a light-shielding plate increases. For this reason, the interference between the light shielding plate and the workpiece can be easily avoided.

  In the laser processing apparatus according to the second aspect of the present invention, in the apparatus of the first aspect, the light shielding plate is disposed at a position where the primary light from the diffractive optical element passes and light of the second or higher order is shielded. Yes.

  Here, as described above, higher-order laser light can be shielded by the light shielding plate, and interference between the light shielding plate and the workpiece can be easily avoided.

  The laser processing apparatus according to the third aspect of the present invention further includes rotation means for rotating the laser light branching means around the optical axis of the input laser light in the apparatus of the first or second aspect.

  Here, since the branched laser beam is rotated, high-speed processing can be performed.

  The laser processing apparatus according to the fourth aspect of the present invention is the laser processing apparatus according to any one of the first to third aspects, wherein the second condensing means has a fixed focal length and is light with respect to the first condensing means. The lens is movable in the axial direction. Further, a moving mechanism for moving the work table in the optical axis direction is further provided.

  Here, the magnification of the image formed on the workpiece is controlled by moving relative to the second condensing unit and the first condensing unit and moving the work table to an appropriate position. can do.

  The laser processing apparatus according to the fifth aspect of the present invention is the apparatus according to any one of the first to third aspects, wherein the second condensing means has a zoom lens having a variable focal length.

  Here, since the second condensing means is composed of a zoom lens, the magnification of the image formed on the workpiece can be controlled, and there is no need to move the work table.

  The laser processing apparatus according to the sixth aspect of the present invention is the laser processing apparatus according to any one of the first to fifth aspects, wherein the laser beam branching unit is configured such that the laser beam focused by the second focusing unit is on one circumference. The laser beam is branched so as to be located at.

  The laser processing apparatus according to the seventh aspect of the present invention is the laser processing apparatus according to any one of the first to sixth aspects, wherein the laser beam condensed by the condensing means is arbitrarily selected within a plane along the surface of the workpiece. A laser beam scanning unit for scanning in the direction is further provided.

  In the present invention as described above, when a diffractive optical element is used for branching laser light, high-order diffracted light can be shielded with a simple configuration.

1 is an external perspective view of a laser processing apparatus according to an embodiment of the present invention. The expansion perspective view of a work table. The perspective view which expands and shows the structure of a laser irradiation head. The schematic diagram which shows the hollow motor and imaging unit containing DOE. The figure which shows an example of an imaging unit. The figure for demonstrating the position of a light-shielding plate. The schematic diagram explaining the operation | movement which scans a condensing point. The schematic diagram explaining the effect | action which controls a condensing point to a Z-axis direction. The figure which shows the structure of the imaging unit for imaging with high magnification. The figure which shows the structure of the imaging unit for imaging with low magnification. The figure which shows the other example of imaging (condensing position). The figure which shows the further another example of image formation (condensing position).

[overall structure]
FIG. 1 shows the overall configuration of a laser processing apparatus according to an embodiment of the present invention. This laser processing apparatus is an apparatus for performing processing such as drilling by irradiating a laser beam, for example, on a glass substrate as a workpiece. This apparatus includes a bed 1, a work table 2 on which a glass substrate as a work is placed, and a laser light irradiation head 3 for irradiating the glass substrate with laser light. Here, as shown in FIG. 1, in the plane along the upper surface of the bed 1, the axes orthogonal to each other are defined as the X axis and the Y axis, and the vertical axis orthogonal to these axes is defined as the Z axis. Further, both directions (+ direction and − direction) along the X axis are defined as the X axis direction, both directions along the Y axis are defined as the Y axis direction, and both directions along the Z axis are defined as the Z axis direction.

[Work table and its moving mechanism]
<Worktable 2>
The work table 2 is formed in a rectangular shape, and a table moving mechanism 5 for moving the work table 2 in the X-axis direction and the Y-axis direction is provided below the work table 2.

  The work table 2 has a plurality of blocks 6 as shown in an enlarged view in FIG. The plurality of blocks 6 are members for lifting and supporting the glass substrate G indicated by the two-dot chain line in the drawing from the surface of the work table 2, in order to avoid a processing line L (shown by a broken line) of the glass substrate G. In addition, it can be attached to an arbitrary position of the work table 2. The work table 2 is formed with a plurality of air inlets 2a in a lattice shape, and each block 6 is formed with an air inlet hole 6a penetrating in the vertical direction. Then, by connecting the intake hole 6a of the block 6 and the intake port 2a of the work table 2, the glass substrate G disposed on the block 6 can be adsorbed and fixed. The intake mechanism is constituted by a well-known exhaust pump or the like and will not be described in detail.

<Table moving mechanism 5>
As shown in FIG. 1, the table moving mechanism 5 has a pair of first and second guide rails 8 and 9, and first and second moving tables 10 and 11, respectively. The pair of first guide rails 8 is provided on the upper surface of the bed 1 so as to extend in the Y-axis direction. The first moving table 10 is provided on the upper part of the first guide rail 8, and has a plurality of guide portions 10 a that are movably engaged with the first guide rail 8 on the lower surface. The second guide rail 9 is provided on the upper surface of the first moving table 10 so as to extend in the X-axis direction. The second moving table 11 is provided on the upper part of the second guide rail 9 and has a plurality of guide portions 11 a that are movably engaged with the second guide rail 9 on the lower surface. The work table 2 is attached to the upper part of the second moving table 11 via a fixing member 12.

  By the table moving mechanism 5 as described above, the work table 2 is movable in the X-axis direction and the Y-axis direction. The first and second moving tables 10 and 11 are driven by a driving means such as a well-known motor, although details are omitted.

[Laser beam irradiation head 3]
As shown in FIGS. 1 and 3, the laser light irradiation head 3 is mounted on a portal frame 1 a disposed on the upper surface of the bed 1. It has a hollow motor 17 in which an optical element is incorporated, and an imaging unit 20 (details will be described later) including a lens and a light shielding plate. Further, an X-axis direction moving mechanism 21 for moving the laser light irradiation head 3 in the X-axis direction, and a Z-axis direction moving mechanism 22 for moving the hollow motor 17 and the imaging unit 20 in the Z-axis direction are provided. Is provided.

<Laser light output unit 15>
The laser beam output unit 15 is composed of a laser tube similar to the conventional one. The laser light output unit 15 emits green laser light having a wavelength of 532 nm to the opposite side of the work table 2 along the Y axis.

<Optical system 16>
The optical system 16 guides the laser light from the laser light output unit 15 to a diffractive optical element (described later) incorporated in the hollow motor 17. The optical system 16 includes first to fourth mirrors 25 to 28, a power monitor 29 for measuring laser output, and a beam expander 30, as shown in an enlarged manner in FIG.

  The first mirror 25 is disposed in the vicinity of the output side of the laser beam output unit 15 and reflects the laser beam emitted in the Y axis direction in the X axis direction. The second mirror 26 is arranged side by side with the first mirror 25 in the Y-axis direction, reflects the laser light traveling in the X-axis direction in the Y-axis direction, and guides it to the work table 2 side. The third mirror 27 is disposed above the hollow motor 17 and guides the laser light reflected by the second mirror 26 downward (Z-axis direction). The fourth mirror 28 is disposed close to the horizontal direction of the hollow motor 17 and guides the laser beam reflected by the third mirror 27 to the hollow motor 17. The beam expander 30 is disposed between the second mirror 26 and the third mirror 27, and is provided to spread the laser light reflected by the second mirror 26 into a parallel light beam having a constant magnification. This beam expander 30 makes it possible to focus laser light on a smaller spot.

<Hollow motor>
As shown in the schematic diagram of FIG. 4, the hollow motor 17 has a rotation shaft extending in the X-axis direction at the center, and a central portion 17a including the rotation shaft is hollow. A diffractive optical element (hereinafter referred to as “DOE”) 34 is fixed to the hollow portion 17a. The diffractive optical element 34 branches the inputted laser light into a plurality of light beams.

<Imaging unit>
The configuration of the imaging unit 20 is shown in FIG. FIG. 5 is a diagram showing the relationship between the DOE 34 and the imaging unit 20, and other configurations are omitted.

  The imaging unit 20 includes a condensing lens (first condensing unit) 201, a light shielding plate 202, and a relay lens (second condensing unit) 203. The condensing lens 201 is a lens for condensing a plurality of branched laser beams from the DOE 34 above the glass substrate. The light shielding plate 202 is disposed between the condenser lens 201 and the relay lens 203. In this example, the light shielding plate 202 is disposed at the condensing position (focal plane) of the condensing lens 201, but the position of the light shielding plate 202 will be described later. A circular opening 202 a having a predetermined diameter is formed at the center of the light shielding plate 202. The relay lens 203 is disposed between the light shielding plate 202 and the glass substrate G. By the relay lens 203, a plurality of laser beams that have passed through the light shielding plate 202 are condensed on the glass substrate G or at arbitrary positions in the Z-axis direction in the glass substrate G.

  Note that the condensing position in the Z-axis direction by the relay lens 203 can be controlled only within a limited range of, for example, about 30 mm in both the X-axis direction and the Y-axis direction.

<Position of shading plate>
FIG. 6 shows a position where the light shielding plate 202 should be arranged. FIG. 6 shows only the upper half of the light shielding plate 202 of FIG. Also, the broken line 2Lu is the upper ray of the secondary light of the DOE 34, the broken line 2Ll is the lower ray of the secondary light, the solid line 1Lu is the upper ray of the primary light, and the solid line 1Ll is the lower ray of the primary light. is there.

  FIG. 6A shows a case where the light shielding plate 202 is arranged at a position where the upper light beam 1Lu of the primary light and the lower light beam 2Ll of the secondary light intersect. Since there is a portion where the primary light and the secondary light overlap on the left side of the figure (condensing lens 201 side) from this position, it is not appropriate as the position where the light shielding plate 202 is disposed.

  FIG. 6C shows a case where the light shielding plate 202 is arranged at a position where the lower light beam 1Ll of the primary light and the upper light beam 2Lu of the secondary light intersect. The primary light and the secondary light overlap each other on the right side of the figure (relay lens 203 side) from this position, and the light shielding plate 202 cannot be disposed.

  From the above, the range of FIG. 6A to FIG. 6C is a region where the light shielding plate 202 should be disposed.

<Support and transport system of laser beam irradiation head>
The laser beam irradiation head 3 is supported by the portal frame 1a of the bed 1 as described above. More specifically, as shown in FIG. 3, a pair of third guide rails 36 extending in the X-axis direction are provided on the upper surface of the portal frame 1a. The drive mechanism that does not constitute the X-axis direction moving mechanism 21. A support member 37 is movably supported by the pair of third guide rails 36. The support member 37 includes a horizontal support member 38 supported by the third guide rail 36 and a vertical support member 39 extending downward from one end of the horizontal support member 38 on the work table 2 side. A pair of fourth guide rails 40 extending in the Z-axis direction are provided on the side surface of the vertical support member 39, and the pair of fourth guide rails 40 and a driving mechanism (not shown) drive the Z-axis direction moving mechanism 22. It is composed. A third moving table 41 is supported on the fourth guide rail 40 so as to be movable in the Z-axis direction.

  The laser beam output unit 15, the first to third mirrors 25 to 27, the power monitor 29, and the beam expander 30 are supported by the lateral support member 38. Further, the fourth mirror 28, the hollow motor 17, and the imaging unit 20 are supported by the third moving table 41.

[Operation]
Next, the processing operation of the glass substrate by the laser will be described.

  First, a plurality of blocks 6 are installed on the surface of the work table 2. At this time, the plurality of blocks 6 are arranged so as to avoid the processing line L of the glass substrate G, as shown in FIG. The glass substrate G to be processed is placed on the plurality of blocks 6 installed as described above.

  Next, the laser beam irradiation head 3 is moved in the X axis direction by the X axis direction moving mechanism 21, and the work table 2 is moved in the Y axis direction by the table moving mechanism 5. The light spot is positioned at the start position of the processing line L.

  After the laser light irradiation head 3 and the glass substrate G are moved to the processing position as described above, the processing is performed by irradiating the glass substrate G with the laser light. Here, the laser beam emitted from the laser beam output unit 15 is reflected by the first mirror 25 and guided to the second mirror 26. The laser output of the laser light incident on the first mirror 25 is measured by the power monitor 29. The laser light incident on the second mirror 26 is reflected in the Y-axis direction, and the light beam is expanded by the beam expander 30 and guided to the third mirror 27. The laser beam reflected by the third mirror 27 and further reflected by the fourth mirror 28 is input to a DOE 34 provided at the center of the hollow motor 17.

  A plurality of condensing points are formed on the glass substrate G by the DOE 34 and the imaging unit 20. This operation will be described in detail below.

  FIG. 7 schematically shows the operation of the DOE 34 and the imaging unit 20. The imaging unit 20 is shown in a simplified manner. The laser light input to the DOE 34 is branched into a plurality according to the specifications of the DOE 34. In this example, the DOE 34 and the imaging unit 20 form an example in which four focal points (condensing points) arranged at 90 ° intervals on the circumference are formed. Then, by rotating the DOE 34 by the hollow motor 17, it is possible to rotate all four condensing points around their central axes C.

  Then, by controlling the table moving mechanism 5, all four rotating condensing points are moved in the X-axis direction and the Y-axis direction, and along the processing line L (rectangular in FIG. 2, circular in FIG. 4). Let it scan. That is, the four condensing points are scanned along the processing line while rotating around their central axis C.

  At this time, since the image forming unit 20 is provided with the light shielding plate 202, the secondary light of the laser light from the DOE 34 is shielded by the light shielding plate 202 and is not irradiated onto the glass substrate G. For this reason, the damage to the glass substrate G by secondary light can be eliminated.

  Here, the height at which the glass is removed by one processing with a laser beam is several tens of μm. Therefore, when a hole is formed in the glass substrate G, it is generally possible to form a hole even if the condensing point is scanned only once along the processing line, that is, to remove a portion inside the processing line. Have difficulty.

  Therefore, normally, first, the imaging unit 20 is controlled so that the condensing point (processing part) is formed on the lower surface of the glass substrate G (see FIG. 8A). In this state, after the image forming position (condensing point) of the image forming unit 20 makes one round along the processing line, the image forming unit 20 is controlled, as shown in FIG. To raise. Similarly, after the condensing point makes one turn along the processing line, the condensing point is further raised. By repeatedly executing the above operation, a hole can be formed by removing the inner portion of the processing line.

  In addition, when a processing line covers a wide range, after performing the above-described processing, the position of the glass substrate G is changed by moving the work table 2 in the X-axis direction and the Y-axis direction by the table moving mechanism 5. Then, in the same manner as described above, the table moving mechanism 5 may be controlled and processed by scanning with laser light.

[Feature]
In the present embodiment as described above, the light shielding plate 202 can be disposed at a position away from the glass substrate G as a workpiece, and interference between the light shielding plate 2020 and the workpiece can be avoided. Therefore, when the DOE is used for branching the laser light, the secondary light can be easily shielded, and the work can be prevented from being damaged by the high-order light.

[Other Embodiments]
The present invention is not limited to the above-described embodiments, and various changes or modifications can be made without departing from the scope of the present invention.

  (A) By controlling the position of the relay lens 203 provided in the imaging unit 20, the magnification of the image formed on the glass substrate G can be changed.

  For example, FIG. 9 shows a case where an image is formed on the glass substrate G at a high magnification (FIG. 9B) from the state shown in FIG. 5 (FIG. 9A). In the case of forming an image on the glass substrate G at a high magnification, it can be realized by making the distance between the condensing lens 201 and the relay lens 203 closer. In this case, as shown in FIGS. 9A and 9B, the position of the glass substrate G also needs to be changed.

  FIG. 10 shows a case where an image is formed on the glass substrate G at a low magnification (FIG. 10B) from the state shown in FIG. 5 (FIG. 10A). In the case of forming an image on the glass substrate G at a low magnification, it can be realized by further increasing the distance between the condenser lens 201 and the relay lens 203. In this case as well, as in FIG. 9, it is necessary to change the position of the glass substrate G as shown in FIGS. 10 (a) and 10 (b).

  In the example shown in FIGS. 9 and 10, it is necessary to change the position of the glass substrate G. However, when the relay lens is a zoom lens having a variable focal length instead of a fixed focal length, the position of the glass substrate G is changed. Can be fixed.

  (B) In the above embodiment, as shown in FIG. 7, two condensing points are formed on the circumference, but the number and arrangement of the condensing points are not limited to this. For example, as shown in FIG. 11, the laser beam may be branched into four and these condensing points may be arranged in a straight line. In this case, the laser beam is irradiated uniformly within the processing width.

  Moreover, as shown in FIG. 12, you may form so that several condensing points may be arrange | positioned radially. Specifically, in the example of FIG. 12, four condensing points are formed at equal angular intervals on the circumference, and each of these condensing points is linear in the X axis direction and the Y axis direction. Are formed so that four condensing points are arranged at regular intervals.

  (C) In the said embodiment, although the glass substrate was used as a workpiece, the workpiece should just be a member which can be processed with a laser beam, and is not limited to a glass substrate.

2 Work table 3 Laser light irradiation head 5 Table moving mechanism 14 Image rotator 15 Laser light output unit 17 Hollow motor 20 Imaging unit 34 Diffractive optical element (DOE)
201 condensing lens 202 light shielding plate 203 relay lens

Claims (7)

A processing apparatus that performs processing by irradiating a workpiece with laser light,
A work table on which a workpiece is placed;
A laser beam output unit for outputting a laser beam;
A laser beam branching unit that includes a diffractive optical element and branches the laser beam from the laser beam output unit into a plurality of laser beams;
First condensing means for condensing laser light from the laser light branching means;
A light-shielding plate disposed between the first condensing means and the work table, which shields a higher-order laser beam than the predetermined of the diffractive optical element;
Second condensing means for condensing the laser beam that has passed through the light shielding plate on the workpiece;
A laser processing apparatus comprising:   2. The laser processing apparatus according to claim 1, wherein the light shielding plate is disposed at a position where primary light from the diffractive optical element passes and light of second or higher order is shielded.   3. The laser processing apparatus according to claim 1, further comprising a rotating unit configured to rotate the laser beam branching unit around an optical axis of the input laser beam. The second light collecting means is a lens having a fixed focal length and movable in the optical axis direction with respect to the first light collecting means,
A moving mechanism for moving the work table in the optical axis direction;
The laser processing apparatus according to claim 1.   The laser processing apparatus according to any one of claims 1 to 3, wherein the second light condensing unit includes a zoom lens having a variable focal length.   The laser processing according to any one of claims 1 to 5, wherein the laser beam branching unit branches the laser beam so that the laser beam focused by the second focusing unit is positioned on one circumference. apparatus.   The laser beam scanning part for scanning the laser beam condensed by the said 2nd condensing means in arbitrary directions within the plane along the surface of the said to-be-processed object was further provided. The laser processing apparatus of crab.

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