JP4874030B2 - Laser processing head - Google Patents

Description

  The present invention relates to a technical field in which laser processing such as drilling, grooving, cutting, and the like is performed on an object to be processed such as a hard brittle material such as a metal material, a semiconductor material, and ceramics with a laser beam.

Conventionally, a laser processing head is provided with a condensing lens in a cylindrical lens holder, condenses laser light generated by a laser oscillator, and condenses laser light collected from a tapered nozzle provided at the tip. Laser processing such as drilling, grooving, cutting, etc. is performed while irradiating the object to be processed and simultaneously blowing out gas from the nozzle to prevent adhesion of processing by-products. As such a structure, for example, Japanese Patent Application Laid-Open No. 60-27487 discloses the structure thereof.
JP-A-60-27487

  Laser light with linearly polarized light generated by a laser oscillator has different vertical and horizontal photoelectric field vibration intensities. The scanning speed is high when scanning in the strongly oscillating polarization direction, and the processing speed when scanning in the weakly oscillating polarization direction. Becomes slower. For this reason, when grooving is performed, the width of the groove differs in the scanning direction. As a countermeasure, a technique is known in which a quarter-wave plate is introduced on the optical path, the laser light is converted into circularly polarized light, and then the object to be processed is irradiated to process with a uniform width of the groove. Yes.

On the other hand, when the laser beam reflected by the quarter-wave plate returns to the laser oscillator (return light), the laser oscillator is damaged or becomes unstable. Therefore, it is conceivable to apply a non-reflective coating to the wave plate so that the laser beam does not return to the laser oscillator. However, wave plates with anti-reflection coatings generally have low light resistance, so if you want to increase the laser output, you must use wave plates without anti-reflection coating, and the laser beam is damaged by the return light. The above problems such as receiving are caused.
In view of the problems of the prior art, the present invention provides a laser processing that can reduce damage and instability of a laser oscillator due to return light even if a quarter-wave plate is introduced into the optical path. The object is to provide a head.

In order to achieve the above object, the present invention takes the following technical means.
That is, the present invention is a laser processing head for performing predetermined processing by irradiating an object to be processed with laser light, a quarter wavelength plate for converting generated laser light from linearly polarized light to circularly polarized light, and this A condensing lens that condenses laser light converted to circularly polarized light by a quarter-wave plate, a protective glass disposed closer to the object to be processed than the condensing lens, and a processing by-product (commonly called dross) Is provided at the tip of the laser processing head, and discharges the gas to the processing target side. The gas jetting means forms a gas flow for preventing the gas from adhering to the surface and processing surface of the processing target. A laser processing head comprising: a tapered nozzle; and a wave plate adjusting means for adjusting a rotation angle of the quarter wave plate with an optical axis as a rotation axis .

  According to the laser processing head of the present invention, since the quarter-wave plate is introduced into the laser processing head, the quarter-wave plate can be further away from the laser oscillator than the conventional one, and the quarter wavelength plate It is possible to reduce damage and instability of the laser oscillator due to the return light from the plate. Further, the laser processing optical device can be made compact.

In order to convert from linearly polarized light to circularly polarized light with the ¼ wavelength plate, it is necessary to adjust the rotation angle. Therefore, the adjustment of the rotation angle is simplified by the wavelength plate adjusting means.

In the present invention, the condenser lens is preferably an aspheric lens.
In this case, it is possible to perform good processing with little dross, taper, chipping, sagging, and the like.

In the present invention, a condenser lens adjusting unit that adjusts a position of the condenser lens in a direction orthogonal to the optical axis and a nozzle adjusting unit that adjusts the position of the nozzle in a direction orthogonal to the optical axis are provided. It is preferable.
In this case, it is possible to easily adjust the positions of the condenser lens and the nozzle.

In the present invention, the protective glass is preferably made of glass having a pressure strength of 100 kPa to 2000 kPa.
In this case, a sufficient gas pressure can be supplied to the laser processing head, and adhesion of processing by-products (dross) can be effectively prevented.

  As described above, according to the present invention, by introducing the quarter wavelength plate into the laser processing head, the quarter wavelength plate is moved away from the laser oscillator, and the laser beam is damaged by the return light. Instability can be reduced.

  Hereinafter, embodiments of the present invention will be described. FIG. 1 shows an embodiment of a laser processing optical system 1 including a laser processing head according to the present invention, and FIG. 2 shows a schematic sectional view of the laser processing head 2. The laser processing optical system 1 is for performing predetermined processing by irradiating a laser beam onto an object to be processed, and includes a laser oscillator 3 that outputs YAG laser light, and a beam expander 4 that expands the laser beam diameter. A folding mirror 5 and a laser processing head 2. With this laser processing optical system 1, for example, grooving of a single crystal diamond 51 placed on a glass substrate 50 is performed.

  The laser processing head 2 includes a cylindrical head body 6, a quarter wavelength plate 7 provided on the head body, an aspheric lens 8 as a condensing lens for condensing laser light, and the aspheric lens. 8, a lens holder 9 that supports 8, a protective glass 10 provided on the tip side of the aspherical lens 8, a gas ejection means 12 that supplies gas to the internal space 11 in the laser processing head 2, and the laser processing head 2. The nozzle 13 provided at the tip of the lens, the wave plate adjusting means 14 for adjusting the rotation angle of the quarter wave plate 7, the lens adjusting means 15 for adjusting the position of the aspherical lens 8, and the position adjustment of the nozzle. Nozzle adjustment means 16 is provided.

  The quarter-wave plate 7 is a birefringent optical element that converts laser light generated by the laser oscillator 3 from linearly polarized light to circularly polarized light. The wave plate adjusting means 14 includes an adjusting plate 14k provided on the head body 6 and a handle 14t fixed to the outer periphery of the adjusting plate 14k. By rotating the handle 14t, the optical axis is a rotation axis 1 The rotation angle of the / 4 wavelength plate 7 can be adjusted. A cylindrical lens holder 9 is attached to the front end side of the head main body 6, and a fixing ring 17 fixed to the outer periphery of the aspherical lens 8 is incorporated in the lens holder 9.

  The lens adjusting means 15 is provided in the lens holder 9 so as to adjust the position of the aspherical lens 8 and the aspherical lens 8, which is not shown in the figure, the inner surface of which is in contact with the outer periphery of the fixing ring 17. It consists of two screws 15n screwed into the lens holder 9 and having their tips abutted against the outer periphery of the fixing ring 17. And the position of the aspherical lens 8 in the direction orthogonal to the optical axis can be changed by changing the screwing degree of these two screws 15n. Thereby, the position of the aspherical lens 8 with respect to the laser light can be easily adjusted.

  The protective glass 10 is made of glass having a pressure strength of 100 kPa to 2000 kPa, and is fixed to the front end side in the lens holder 9. The protective glass 10 prevents the aspherical lens 8 from being affected by the gas pressure, and effectively prevents spatters scattered from the workpiece during processing from adhering to the aspherical lens 8. The value of 100 kPa, which is the lower limit of the pressure strength, is a value that allows for safety so that the glass can sufficiently withstand the required gas pressure.

  The nozzle 13 is composed of a disk-shaped nozzle seat portion 13z and a tapered nozzle body 13h attached to the lens holder 9 via the nozzle seat portion 13z, and is supplied to the internal space 11. The gas is discharged near the processing focal point. The nozzle adjustment means 16 includes an adjustment seat 16c provided on the outer periphery of the nozzle seat 13z, and four adjustment screws 16n screwed into the adjustment seat 16c from four directions. By changing the screwing degree of these adjusting screws 16n, the position of the nozzle body 13h in the direction orthogonal to the optical axis can be easily changed. The gas ejection means 12 includes a gas storage part (not shown) and a gas circulation part 12 g provided on the tip end side of the lens holder 9 and communicating with the internal space 11. The pressurized gas supplied from the gas circulation part 12 flows through the internal space 11 and is ejected at a high speed from the opening at the tip of the nozzle body 13h. Thereby, adhesion of the processing by-product to the protective glass 10 grade | etc., Is prevented.

  When grooving the single crystal diamond 51 with the laser processing optical system 1 described above, the laser beam diameter generated by the laser oscillator 3 is expanded by the beam expander 4 and the angle of the laser beam is changed by the folding mirror 5. Then, the light is incident on the laser processing head 2. Then, the quarter-wave plate 7 introduced into the laser processing head 2 converts the laser light from linearly polarized light to circularly polarized light, and scans the single crystal diamond 51 with the laser light having circularly polarized light to perform grooving.

  According to the laser processing head 2 of the above embodiment, since the quarter wavelength plate 7 is introduced into the processing head 2, the quarter wavelength plate 7 can be further away from the laser oscillator 3 than in the prior art. It is possible to reduce the damage or instability of the laser oscillator 3 due to the return light from the / 4 wavelength plate 7. Further, the laser processing optical system 1 can be made compact. Further, in order to convert the linearly polarized light into the circularly polarized light by the quarter wavelength plate 7, it is necessary to adjust the rotation angle, but the adjustment by the wavelength plate adjusting means 14 is simple.

Further, since the condensing lens is the aspherical lens 8, it is possible to perform good processing with less dross, taper, chipping, surface sag, and the like. Moreover, since the protective glass 10 has a pressure strength of 100 kPa to 2000 kPa, a sufficient gas pressure can be supplied to the laser processing head 2, and the adhesion of processing by-products (dross) can be effectively prevented. can do.
In addition, this invention is not limited to the said embodiment, The shape of a quarter wave plate is not limited, A wave plate adjustment means, a lens adjustment means, and a nozzle adjustment means may employ | adopt the thing of another form. Good.

It is the schematic of the optical apparatus for laser processing concerning this embodiment. It is a cross-sectional schematic diagram of a laser processing head.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser processing optical system 2 Laser processing head 3 Laser oscillator 6 Head main body 7 Wavelength plate 8 Condensing lens 10 Protective glass 12 Gas ejection means 13 Nozzle 14 Wavelength plate adjustment means 15 Lens adjustment means 16 Nozzle adjustment means

Claims (4)

A laser processing head for performing predetermined processing by irradiating an object to be processed with laser light, a quarter wavelength plate for converting the generated laser light from linearly polarized light to circularly polarized light, and this quarter wavelength A condensing lens for condensing laser light converted into circularly polarized light by a plate, a protective glass disposed on the processing object side with respect to the condensing lens, and a processing by-product on the surface and processing surface A gas jetting means for forming a gas flow for preventing the gas from adhering to the nozzle, a tapered nozzle provided at the tip of the laser processing head for discharging the gas to the processing object side, and an optical axis as a rotation axis And a wavelength plate adjusting means for adjusting a rotation angle of the quarter wavelength plate . The laser processing head according to claim 1 , wherein the condenser lens is an aspheric lens . 3. A condensing lens adjusting unit that adjusts a position of the condensing lens in a direction orthogonal to the optical axis, and a nozzle adjusting unit that adjusts the position of the nozzle in a direction orthogonal to the optical axis. The laser processing head described in 1. The laser processing head according to claim 1, wherein the protective glass is made of glass having a pressure strength of 100 kPa to 2000 kPa .

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