KR20120016782A - Laser machinning apparatus and method - Google Patents

Abstract

PURPOSE: A laser processing apparatus and method are provided to maintain constant energy of a laser beam irradiated on a work piece and reduce the output of an oscillator, thereby reducing power consumption. CONSTITUTION: A laser processing method is as follows. An oscillated laser beam is irradiated on a transparent work piece(50) through a first optical path(101). The laser beam passing through the work piece is collected through a second optical path(102). The collected laser beam is joined to the first optical path and irradiated on the work piece again.

Description

Laser Machining Apparatus and Method

The present invention relates to a laser processing apparatus and method, and more particularly, to a laser processing apparatus and method for performing a machining operation by irradiating a laser beam to a light-transmissive object.

A laser processing machine refers to a device that irradiates a laser beam to a workpiece to perform machining operations such as marking, exposure, etching, scribing, and cutting on the workpiece by the energy of the laser beam. When the object to be processed is a light-transmitting material such as glass or sapphire substrate, part of the irradiated laser beam may pass through the object to be processed, which may lower energy efficiency.

An object of the present invention is to provide a laser processing machine and a processing method which can recover a laser beam transmitted through a light-transmissive processing object and reuse it for processing.

The laser processing method of the present invention for achieving the above object comprises the steps of: irradiating an oscillating laser beam to a light-transmissive object through a first optical path; Recovering the laser beam transmitted through the object through a second optical path; And synthesizing the recovered laser beam into the first optical path and irradiating the object to be processed again.

The processing method may further include converting the recovered laser beam into a polarization direction different from the polarization direction of the oscillated laser beam, wherein the recovered laser beam is selectively transmitted / reflected according to the polarization direction. A beam may be synthesized into the first optical path.

In the processing method, the transmitted laser beam may be converted into parallel light and recovered in the second optical path.

The processing method may further include condensing the laser beam of the first optical path at a predetermined position of the object to be processed by using a condenser lens.

The condenser lens may condense the laser beam onto the surface of the object to be processed.

The condenser lens may condense the laser beam inside the object to be processed. The laser beam on the first optical path may be divided into a plurality of laser beams, and the plurality of laser beams may be focused at different positions in the thickness direction of the object to be processed using the condenser lens. The plurality of laser beams may be disposed such that a laser beam that is focused below the thickness direction of the processing object is positioned forward in the processing direction.

Laser processing for achieving the above object is a laser oscillator for generating a laser beam; A first optical path for guiding the laser beam to an object to be processed; A second optical path for recovering a laser beam that has passed through the object; And a light path synthesis member for synthesizing the second light path with the first light path such that the recovered laser beam is irradiated to the object to be processed through the first light path.

The processing unit may further include a polarization conversion member positioned in the second optical path and converting the recovered laser beam into a polarization direction different from the polarization direction of the oscillated laser beam, wherein the optical path synthesis member comprises a polarization direction. It may be a polarizing mirror that selectively transmits / reflects the laser beam depending on.

The processing machine may further include a collimating lens for converting the transmitted laser beam into parallel light and recovering it to the second optical path.

The processing machine may further include a condenser lens positioned on the first optical path to condense the laser beam at a predetermined position of the object to be processed.

The condenser lens may condense the laser beam onto the surface of the object to be processed.

The condenser lens may condense the laser beam inside the object to be processed.

The processing unit may further include a beam splitter configured to split the laser beam on the first optical path into a plurality of laser beams, wherein the condenser lens collects the plurality of laser beams at different positions in a thickness direction of the object to be processed. You can. The plurality of laser beams may be disposed such that a laser beam that is focused below the thickness direction of the processing object is positioned forward in the processing direction.

According to the laser processing machine and processing method of the present invention described above, the laser beam transmitted through the light-transmissive processing object can be recovered and irradiated to the processing object, thereby improving energy efficiency. When employing a laser oscillator having the same output, the energy of the laser beam irradiated to the processing object can be increased. In addition, if the energy of the laser beam irradiated to the processing object is constant, the output of the oscillator can be lowered by the reusable power can be lowered the power consumption.

1 is a block diagram of a laser processing machine according to an embodiment of the present invention.
2 is a cross-sectional view showing a state in which a laser beam is focused on the inside of a workpiece.
3 is a block diagram of a laser processing machine according to another embodiment of the present invention.
4 is a view for explaining an arrangement of a plurality of laser beams along a processing direction.

Hereinafter, with reference to the accompanying drawings, a preferred embodiment of the laser processing method and apparatus of the present invention will be described in detail.

1 is a block diagram of an embodiment of a laser processing machine according to the present invention. 1, a table 40 on which a light-transmitting material such as glass, a sapphire substrate, or the like is placed, and a laser oscillator 10 for generating a laser beam are shown. The laser beam irradiated from the oscillator 10 is reflected by, for example, the reflective mirror 20 and irradiated to the object 50 through the first optical path 101. In the first optical path 101, a condenser lens 30 for condensing a laser beam on the object 50 may be disposed. The condenser lens 30 may be an assembly of a plurality of optical members for condensing a laser beam at a desired position in the thickness direction of the object to be processed 50 according to the purpose of processing. This type of condenser lens 30 is well known in the art, and thus detailed description thereof will be omitted.

A portion of the laser beam irradiated to the processing object 50 through the first optical path 101 may not be used as an effective energy for processing the processing object 50 and may pass through the processing object 50. The present invention is characterized in that the laser beam transmitted through the second optical path 102 can be recovered and irradiated to the object 50 through the first optical path 101.

For example, as shown in FIG. 1, the table 40 is provided with an opening 41 through which the transmitted laser beam can pass. The rear surface of the object 50 may be provided with a plurality of reflecting mirrors 21, 22, 23 for guiding the transmitted laser beam to the first optical path 101. The transmitted laser beam is sequentially reflected by the reflection mirrors 21, 22, 23 and guided along the second optical path 102 to the first optical path 101. In order to guide the laser beam recovered through the second optical path 102 to the first optical path 101 at the position where the first and second optical paths 101 and 102 intersect, the first and second optical paths are arranged. An optical path combining member for synthesizing the furnaces 101 and 102 may be disposed.

This embodiment employs a polarizing mirror 60 that selectively transmits or reflects depending on the polarization direction of light as the optical path combining member. The laser beam emitted from the oscillator 10 and incident on the polarization mirror 60 is a single polarized light having a constant polarization direction. The polarization mirror 60 guides the first optical path 101 by transmitting the laser beam. The second optical path 102 is disposed with a polarization conversion member 70 for converting the polarization direction of the recovered laser beam into light having a polarization direction different from that of the oscillated laser beam. For example, when the oscillated laser beam has linearly polarized light in the first direction, the polarization converting member 70 converts the recovered laser beam to have linearly polarized light in the second direction orthogonal to the first direction. / λ plate may be. The recovered laser beam is polarized in the second polarization direction by the polarization converting member 70 and is incident on the polarization mirror 60. The polarization mirror 60 synthesizes the first optical path 101 by reflecting the recovered laser beam. As a result, the recovered laser beam may be irradiated to the object 50 through the first optical path 101.

A part of the recovered laser beam may not be effectively used after being irradiated to the object 50 and may be transmitted again. Since the retransmitted laser light has a second polarization direction, it is converted back to the first polarization direction by the polarization converting member 70 even when recovered through the second optical path 102. Since the laser beam converted in the first polarization direction is transmitted through the polarization mirror 60, it cannot be synthesized into the first optical path 101 and thus cannot be used again. However, only one reuse can greatly increase the use efficiency of the laser beam.

For example, if 80% of the laser beam irradiated onto the object 50 is effectively absorbed, the remaining 20% is discarded. However, since 20% of the recovered laser beam is reusable when one recovery is possible by the laser processing machine according to the present invention, only about 4% of the initially irradiated laser beam is discarded by simple calculation. Therefore, a very high level of use efficiency can be obtained even if only the first transmitted laser beam is reused.

The numerical values provided here are merely exemplary values for showing the effects of the laser processing machine and the processing method according to the present invention, and the scope of the present invention is not limited by these numerical values.

Physical properties of the object to be processed 50 to which the laser beam is irradiated, for example, the refractive index is changed, the shape may also be unevenly changed by the processing. Therefore, the laser beam transmitted through the object 50 can be diffused and scattered. The collimating member 80 may be disposed in the second optical path 102. The collimating member 80 is preferably disposed on the incident side of the reflective mirror 21. The collimating member 80 converts the diffused and scattered laser beam to be parallel to the parallel light while passing through the object 50. Thereby, the ratio of the laser beam recovered by the 2nd optical path 102 among the transmitted laser beams can be improved. In addition, when the laser beam recovered by the second optical path 102 and synthesized by the first optical path 101 is focused on the object 50 by the condenser lens 30, the condensing efficiency may be improved.

As mentioned above, energy efficiency can be improved by collect | recovering and re-irradiating the laser beam which permeate | transmitted the translucent process target object 50. FIG. In addition, when employing the laser oscillator 10 having the same output, the energy of the laser beam irradiated to the object 50 can be increased. In addition, if the energy of the laser beam irradiated to the object to be processed 50 is constant, the output of the oscillator 10 can be lowered by the reusable output can lower the power consumption.

In order to mark, etch, scribe and cut the object 50 into a desired shape, and to expose a laser beam at a desired position of the object 50, the object 50 and the laser beam are moved relative to each other. Can be.

For example, in FIG. 1, the table 40 may move the object to be processed 50 in the XY plane according to the purpose to be processed. That is, although not shown in the drawings, the X-movement shaft is installed on the Y-stage coupled to the Y-movement axis, the XY-stage combining the X-stage on the X-movement axis is provided, and the table is placed on the Y-stage. By mounting 40, the table 40 can be moved in the XY plane by moving the X-stage and the Y-stage in the X and Y directions, respectively. In addition to this, various structures capable of moving the table 40 in the X and Y directions may be employed.

Also for example, the table 40 may be located at a fixed position and the laser beam may be moved in the XY plane. To this end, the oscillator 10, the reflection mirror 20, the optical path combining member, and the condenser lens 30 may be moved in the XY plane in the form of one laser head. In this case, the collimating member 80 and the reflecting mirrors 21, 22, 23, and the polarization converting member 70 disposed on the second optical path 102 are also preferably moved together with the laser head. . Of course, the laser head may be moved only in the X direction and the table 40 may be moved in the Y direction. In this case, the collimating member 80 and the reflecting mirror 21 can be moved in the X direction together with the laser head.

The laser beam may be focused at a predetermined position in the thickness direction or on the surface of the object to be processed 50 depending on the processing purpose.

For example, in the case of surface scribing for cutting brittle materials such as glass, the laser beam is focused on the surface of the object 50 to be processed. Then, the object 50 is locally heated by the energy of the laser beam. The energy of the laser beam is set such that only the heating is generated without the object 50 being vaporized or melted. The locally heated portion tends to thermally expand, but the periphery is not heated and thus cannot expand. Therefore, the compressive stress is locally generated at the portion to which the laser beam is irradiated. The compressive stress is generated radially about the irradiated portion of the laser beam, and tensile stress is generated in the direction orthogonal thereto. When irradiating a laser beam, the energy of the laser beam is controlled so that this tensile stress does not exceed the breaking threshold of the object to be processed 50. When the object 50 is cooled after the laser beam is irradiated, the object 50 is contracted again. At this time, cracks are generated while the tensile stress is amplified, or the physical properties of the material are changed. By such a process, a scribing line may be formed on the surface of the object to be processed 50. It can be cut along the scribing line later by applying mechanical pressure to the workpiece 50 in the braking process.

In addition, a desired pattern can be formed on the surface by applying laser energy to the surface of the object to be processed 50 by fusing, etching, and marking.

In the case of cutting, the laser beam may be focused inward in the thickness direction from the surface of the object to be processed 50. For example, as shown in FIG. 2, when the laser beam is focused inside the object to be processed 50, internal physical properties are changed. In this process, cracks may be formed therein. The crack may grow from the inside to the surface on which the laser beam is incident, depending on conditions such as energy and pulse width of the laser beam. As a result, a cutting line having a crack shape or a physical property change region may be formed inside the object 50. The workpiece 50 can be cut along the cutting line by applying mechanical pressure to the workpiece 50 in the braking process.

In the case of cutting, the laser beam can be focused at a plurality of positions in the thickness direction of the object to be processed 50. For example, when the thickness of the processing target object 50 is thick, a laser beam can be condensed at a plurality of positions in the thickness direction of the processing target object 50 to form a cutting line.

To this end, as shown in FIG. 3, a beam splitter 90 for dividing the oscillated laser beam into a plurality of laser beams may be further provided. The beam splitter 90 may be, for example, a diffraction optical element (DOE). The beam splitter 90 may be disposed on the exit side of the polarization mirror 60. The plurality of laser beams separated by the beam splitter 90 are condensed inside the object 50 by the condenser lens 31.

When the optical axes of the plurality of laser beams are the same, the laser beam incident downward in the thickness direction may be scattered. In other words, the inside of the object 50 to which the laser beam is focused changes its physical properties. At this time, if the property of the upper portion in the thickness direction changes, scattering the laser beam incident downward or changing the propagation path may be performed. It may not collect or may not collect properly.

In this embodiment, as shown in Fig. 3, the plurality of laser beams L1, L2, L3, which are focused at different positions in the thickness direction, are aligned to be positioned at different positions in the processing direction. The machining direction refers to the relative movement direction of the laser beam with respect to the workpiece 50. That is, when the object 50 to be processed is positioned at a fixed position and the reflective mirror 20, the beam separator 90, and the condenser lens 31 are moved in the X direction, the X direction becomes the processing direction. The laser beam L1 condensed at the bottom in the thickness direction is positioned at the foremost in the X direction, next to the laser beam L2, and then to the laser beam L3. According to this configuration, since the uppermost part of the inside of the object 50 is processed by the laser beam L1, the upper part is sequentially processed by the laser beams L2 and L3, so that the laser beam L1 The laser beams L2 and L3 are not affected by the processed portion. Moreover, the laser beam L3 is not influenced by the part processed by the laser beam L2.

If the position of the laser beam is fixed and the object to be processed 50 is moved in the X direction, in this case, the processing direction becomes the -X direction as shown in FIG. ) Is positioned at the forefront in the -X direction, followed by the laser beam L2 and the laser beam L3.

The condenser lens 31 has a form capable of condensing a plurality of laser beams at different positions in the thickness direction of the object to be processed 50. For example, the condenser lens 31 may be a combination of a plurality of lenses having different focal lengths according to regions. Although not shown in the drawings, three condensing lenses corresponding to each of the laser beams L1, L2, and L3 may be provided.

A part of the laser beams L1, L2, and L3 may not be effectively used for processing, but may pass through the processing object 50. The transmitted laser beam is recovered through the second optical path 102 by the reflection mirrors 21, 22, 23. The collimating member 81 converts the transmitted laser beam into light close to parallel light. The second optical path 102 is provided with a polarization converting member 70 to change the polarization direction of the laser beam to be recovered. The polarized laser beam may be reflected by the optical path combining member, for example, the polarization mirror 60, and then incident to the first optical path 101.

By condensing a laser beam inside the object 50, the interior of the object 50 can be processed by changing the physical properties inside the object 50, in addition to forming a line for cutting. For example, an optical waveguide having a desired optical waveguide characteristic can be formed inside the object to be processed by changing the refractive index of a desired position inside the object to be processed 50. In addition, a desired pattern can be formed inside the object 50.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely illustrative, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention should be defined only in the appended claims.

10 ... laser oscillators 20, 21, 22, 23 ... reflective mirrors
30, 31.Condensing lens 40 ... Table
50 ... object 60 ... light path composite member
70 ... polarization conversion member 80, 81 ... collimating member
101 ... First Light Path 102 ... Second Light Path
L1, L2, L3 ... laser beam

Claims (16)

Irradiating the oscillated laser beam to the light-transmissive object through the first optical path;
Recovering the laser beam transmitted through the object through a second optical path;
Synthesizing the recovered laser beam into the first optical path and irradiating the object to be processed again. The method of claim 1,
And converting the recovered laser beam into a polarization direction different from the polarization direction of the oscillated laser beam.
And selectively transmitting / reflecting a laser beam depending on the polarization direction to synthesize the recovered laser beam into the first optical path. The method of claim 1,
And converting the transmitted laser beam into parallel light to recover the second optical path. 4. The method according to any one of claims 1 to 3,
And condensing the laser beam of the first optical path to a predetermined position of the object to be processed by using a condenser lens. The method of claim 4, wherein
The condensing lens condenses the laser beam on the surface of the object to be processed. The method of claim 4, wherein
The condensing lens condenses the laser beam inside the object to be processed. The method of claim 6,
And dividing the laser beam on the first optical path into a plurality of laser beams and condensing the plurality of laser beams at different positions in the thickness direction of the object to be processed using the condenser lens. The method of claim 7, wherein
And the plurality of laser beams are arranged such that a laser beam focused below a thickness direction of the object to be processed is located forward in the processing direction. A laser oscillator for generating a laser beam;
A first optical path for guiding the laser beam to an object to be processed;
A second optical path for recovering a laser beam that has passed through the object;
And an optical path combining member for synthesizing the second optical path with the first optical path so that the recovered laser beam is irradiated to the object to be processed through the first optical path. 10. The method of claim 9,
And a polarization converting member positioned in the second optical path to convert the recovered laser beam into a polarization direction different from the polarization direction of the oscillated laser beam.
And the optical path combining member is a polarizing mirror for selectively transmitting / reflecting a laser beam depending on the polarization direction. 10. The method of claim 9,
And a collimating lens that converts the transmitted laser beam into parallel light and recovers it to the second optical path. 12. The method according to any one of claims 9 to 11,
And a condenser lens positioned on the first optical path and condensing the laser beam at a predetermined position of the object to be processed. The method of claim 12,
The condenser lens condenses the laser beam on the surface of the object to be processed. The method of claim 12,
The condenser lens condenses the laser beam inside the object to be processed. The method of claim 14,
And a beam splitter configured to split the laser beam on the first optical path into a plurality of laser beams.
The condenser lens condenses the plurality of laser beams at different positions in the thickness direction of the object to be processed. 16. The method of claim 15,
And the plurality of laser beams are arranged such that a laser beam that is focused below a thickness direction of the object to be processed is positioned forward in the processing direction.

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