JP2002252396A - Laser oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser oscillator which can improve the quality of a laser beam by suppressing the mixture of scattered light in the beam. SOLUTION: Recessed and projecting sections are formed on the surface of a spacer positioned between mirrors, by adjusting the lengths of edges of the recessed and projecting sections to be 0.02-0.3 times the dimension of the inside diameter of a discharge tube and an inclined angle of the recessed and projecting sections to be 15-45 deg.. In addition, an anodic oxide coating film having a thickness of >=10 μm, is formed on the surface of the spacer, when alumite treatment is conducted to the spacer, or when the spacer is mad of a stainless steel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a laser oscillation device.

[0002]

2. Description of the Related Art FIG. 5 shows an example of a schematic configuration of a conventional axial flow type gas laser oscillation device. Hereinafter, a conventional axial flow gas laser oscillator will be described with reference to FIG.

In FIG. 1, reference numeral 1 denotes a discharge tube made of a dielectric material such as glass, and reference numerals 2 and 3 denote electrodes provided around the discharge tube.

Reference numeral 4 denotes a power supply connected to the electrodes 2 and 3.

[0005] 5 is a discharge tube 1 sandwiched between the electrodes 2 and 3
Inside the discharge space.

Reference numeral 6 denotes a final mirror which is almost totally reflected, and 7 denotes an output mirror which is partially reflected. The final mirror 6 and the output mirror 7 are fixedly arranged at both ends of the discharge space 5, and have an optical resonator. Has formed.

Reference numeral 8 denotes a laser beam output from the output mirror 7.

The arrow 9 indicates the direction in which the laser gas flows, and circulates in the axial flow type gas laser oscillator at a pressure of about 100 to 200 Torr.

Reference numeral 10 denotes a laser gas flow path, and reference numerals 11 and 12 denote heat exchangers for lowering the temperature of the laser gas whose temperature has increased due to the discharge in the discharge space 5 and the operation of the blower.
Reference numeral 13 denotes a blower for circulating a laser gas.
The gas flow of the degree is obtained.

The laser gas flow path 10 and the discharge tube 1 are connected by a laser gas introduction section 14.

The above is the configuration of the conventional gas laser oscillation device, and its operation will now be described.

The laser gas sent from the blower 13 passes through the laser gas flow path 10 and passes through the laser gas introduction section 14.
It is more introduced into the discharge tube 1.

In this state, the electrodes 2, 3 connected to the power source 4
From the discharge space 5.

The laser gas in the discharge space 5 is excited by obtaining the discharge energy, and the excited laser gas is resonated by the optical resonator formed by the last-stage mirror 6 and the output mirror 7, and the laser beam is output from the output mirror 7. A laser beam 8 is output.

The laser beam 8 is used for applications such as laser processing represented by cutting and welding.

[0016]

Problems to be solved by such a conventional laser oscillation device will be described with reference to FIG.

FIG. 6 shows a schematic configuration of an optical resonator portion in a conventional laser oscillation device. The discharge tube 1 is arranged along the optical axis 15 of the optical resonator formed by the last stage mirror 6 and the output mirror 7, and the discharge tube 1 is held by a discharge tube holder 16.

At the time of laser light resonance in the optical resonator, the optical axis 1
Ideally, only the light parallel to 5 is amplified and extracted as a laser beam 8, but actually, scattered light 17 not parallel to the optical axis 15 is generated by reflection or diffraction.

When the scattered light 17 is mixed into the laser beam 8, there is a problem that the quality of the laser beam 8 is deteriorated and, for example, the cutting speed is reduced when performing laser cutting.

As a conventional approach for solving this problem, a hollow spacer 18 called an aperture is arranged near the last-stage mirror 6 and the output mirror 7, and the scattered light 17 is blocked by the hollow spacer 18. Attempts have been made to suppress the scattered light 17 from being mixed into the laser beam 8. However, due to irregular reflection on the surface of the hollow spacer 18,
As a result, another scattered light is generated, and no great effect is obtained.

As disclosed in JP-A-10-22550,
The surface of the hollow spacer 18 is subjected to shot blasting or the like to make minute irregularities (the length of one side is about the same as the laser beam wavelength)
Attempts have been made to disperse the scattered light by the minute unevenness on the surface to attenuate and vanish it, but no great effect has been obtained.

The present invention has been made in view of the above problems.

[0023]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a discharge tube having a laser medium disposed therein, and a laser light emitted from the laser medium excited by the discharge tube. At least one pair of mirrors arranged on the axis, and a spacer arranged between the mirrors, characterized in that irregularities are provided on the surface of the spacer, the length of one side of the irregularities with respect to the inner diameter of the discharge tube, 0.02 times or more, 0.
30 times or less, the inclination angle of the unevenness with respect to the optical axis direction is 15 to 45 degrees, the spacer material is aluminum, and the spacer surface is alumite-treated to a film thickness of 10 μm or more, or the spacer material is stainless steel. It is characterized by.

[0024]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an optical resonator portion of a laser oscillation device according to an embodiment of the present invention.

The discharge tube 1 is arranged along the optical axis 15 of the optical resonator formed by the final mirror 6 and the output mirror 7,
The discharge tube 1 is held by a discharge tube holder 16.

A hollow spacer 18 is arranged adjacent to the discharge tube holder 16.

A surface 19 of the hollow spacer 18 facing the resonance space is provided, and the surface 19 is provided with irregularities 20.

The length of one side of the unevenness 20 is not less than 0.02 times and not more than 0.30 times the inner diameter of the discharge tube.

The inclination angle of the unevenness 20 with respect to the optical axis direction is 15 to 45 degrees.

The spacer material is aluminum, and the surface of the spacer is anodized to a thickness of 10 μm or more.

As described above, at the time of laser light resonance in the optical resonator, it is ideal that only light parallel to the optical axis 15 is amplified and extracted as the laser beam 8.
Actually, scattered light 17 that is not parallel to the optical axis 15 is generated by reflection or diffraction.

Here, the scattered light 17 impinges on the surface 19 of the hollow spacer 18 and is reflected by that surface.

The scattered light 19
Is reflected a plurality of times, and is absorbed and attenuated by the surface 19 for each of the plurality of reflections.

The attenuated scattered light 19 then flies in a direction completely off the optical axis 15, hits the inner wall of the discharge tube 1 and is absorbed and disappears.

As a result, the scattered light 19 hardly mixes into the laser beam 8, and the quality of the laser beam 8 does not deteriorate.

The most effective length of one side of the unevenness 20 is 0.02 times or more and 0.30 times or less with respect to the inner diameter of the discharge tube.

FIG. 2 shows this. If the length of the side is less than 0.02 times the inner diameter of the discharge tube, the length of the side approaches the laser beam wavelength, so that the effect of the diffraction phenomenon increases and the geometrical optical reflection does not occur as intended. , The effect is estimated to be reduced.

On the other hand, when the length of the side exceeds 0.30 times the inner diameter of the discharge tube, the reflected light returns to the resonance space again, and the effect is reduced.

The most effective inclination angle of the unevenness 20 with respect to the optical axis direction is 15 to 45 degrees.

FIG. 3 shows this. It is estimated that the reflection is most effectively performed when the inclination angle is 15 to 45 degrees.

Further, it is more effective if the spacer material is aluminum and the surface is subjected to alumite treatment with a film thickness of 10 μm or more.

This is presumed to be due to the fact that the innumerable holes existing on the surface subjected to the alumite treatment promote the absorption of the scattered light.

When the alumite film thickness is less than 10 μm,
It is considered that the effect is reduced due to the diffraction phenomenon.

It is effective that the spacer material is stainless steel.

It is presumed that this is because the stainless steel itself has a high absorptivity of the laser light, and the scattered light is effectively absorbed.

FIG. 4 is a diagram showing the difference in cutting speed with respect to the thickness of the workpiece between the conventional example and the embodiment of the present invention.

As shown, in the embodiment of the present invention, the scattered light in the energy distribution of the laser beam is reduced, which indicates that the cutting speed is remarkably improved.

[0049]

According to the present invention, it is possible to provide a laser oscillation device capable of suppressing scattering light from being mixed into a laser beam and improving the quality of the laser beam.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an optical resonator portion of a laser oscillation device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between the length of one side of unevenness and the amount of scattered light in a laser beam in the embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between the inclination angle of the unevenness with respect to the optical axis direction and the amount of scattered light in the laser beam in the embodiment of the present invention.

FIG. 4 is a diagram showing a difference in cutting speed with respect to a thickness of a workpiece in a conventional example and an embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of a conventional axial-flow gas laser oscillator.

FIG. 6 is a schematic configuration diagram of an optical resonator portion in a conventional laser oscillation device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 discharge tube 2 electrode 3 electrode 4 power supply 5 discharge space 6 final mirror 7 output mirror 8 laser beam 9 laser gas flow direction 10 laser gas flow path 11 heat exchanger 12 heat exchanger 13 blower 14 laser gas introduction part 15 optical axis 16 discharge Tube holder 17 Scattered light 18 Hollow spacer 19 Surface facing resonance space 20 Roughness

Claims (5)

[Claims] A discharge tube having a laser medium disposed therein;
A laser oscillation comprising at least a pair of mirrors arranged on the optical axis of laser light emitted from a laser medium excited by the discharge tube, and a spacer arranged between the mirrors, wherein the spacer surface has irregularities apparatus. 2. The laser oscillation device according to claim 1, wherein the length of one side of the irregularities is 0.02 to 030 times the inner diameter of the discharge tube. 3. An inclination angle of the unevenness with respect to an optical axis direction,
2. The laser oscillation device according to claim 1, wherein the laser oscillation is 15 to 45 degrees. 4. The laser oscillation device according to claim 1, wherein the spacer material is aluminum, and the spacer surface is subjected to an alumite treatment with a film thickness of 10 μm or more. 5. The laser oscillation device according to claim 1, wherein said spacer material is stainless steel.