JP2584949Y2 - CO2 laser oscillator - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon dioxide laser oscillator.

[0002]

2. Description of the Related Art In a carbon dioxide gas laser oscillator, a mixed gas of CO ₂ , N ₂ , He, etc. is sealed at a predetermined pressure in a laser resonator, and a high voltage is applied thereto to generate a glow discharge. The light emitted from the CO ₂ molecule is amplified by an optical resonator to obtain a laser beam having a high energy density. FIG. 3 is a partially sectional front view showing a structure of a carbon dioxide laser oscillator of a system called a high-speed axial flow type. In the figure, reference numerals 1a and 1b denote discharge tubes formed of an electrically insulating material such as quartz or tempered glass, and 2 denotes discharge tubes 1a and 1b.
Insulating tubes made of the same material as 1b, 3a and 3b are DC high-voltage power supplies, 4a and 4b are holders made of a conductive material such as aluminum for connecting the discharge tubes 1a and 1b and the insulating tube 2;
Reference numerals a and 5b denote cylindrical high-potential cathodes provided in the holders 4a and 4b, and reference numerals 6a and 6b denote anodes provided in the discharge tubes 1a and 1b, which are connected to the high-voltage power supplies 3a and 3b, respectively. In addition, each anode 6a, 6b is electrically grounded for safety. The X ₁ side end portion of the discharge tube 1a with a total reflection mirror 7 is provided, on the X ₂ side end portion of the discharge tube 1b are is provided partially transmitting mirror 8. 9 is a blower for circulating the working gas, 10a is an electrically grounded heat exchanger for removing the heat of the gas whose temperature has been raised by the discharge, 10a
b denotes a heat exchanger for removing the heat of the gas whose temperature has increased due to the compression heat of the blower 9. The discharge tubes 1a, 1b are connected to pipes 11a, 11b for circulating working gas, and the other ends of the pipes 11a, 11b are connected to a heat exchanger 10b. 13a and 13b are holders formed of an insulator such as ceramic. In the carbon dioxide laser oscillator configured as described above, the anode 6a, the cathode 5a, and the anode 6b
By applying a high voltage between the cathode and the cathode 5b, respectively,
A glow discharge is generated between the anode 6a and the cathode 5a and between the anode 6a and the cathode 6b. On the other hand, CO ₂ , N ₂ , He
The working gas composed of the anode 6a, 6b and the cathode 5
It is made to flow at high speed in the direction of the arrow indicated by reference numeral 12 toward a and 5b. Thus, glow discharge is generated to excite the laser. That is, after being repeatedly amplified between the total reflection mirror 7 and the partial transmission mirror 8, the laser light 13 is transmitted through the partial transmission mirror 8 and emitted to the outside.

[0003]

However, in the conventional apparatus shown in FIG. 3, between the cathode and the anode, that is, 5a-6a,
Ions generated by the glow discharge between the electrodes 5b and 6b are accelerated by the potential gradient applied to the cathodes 5a and 5b, become high energy, collide with the surfaces of the cathodes 5a and 5b, and the cathode material is emitted as sputter. Here, a discharge state near the cathode 5a will be described with reference to FIG.

In FIG. 4, reference numeral 14a denotes a glow discharge shape. The discharge tube 1a supported by the holder 13a made of an insulating material and the cathode 5a supported by the holder 4a made of a conductive material are arranged with a gap in the axial direction. On the other hand, the cathode 5a is formed in a cylindrical shape in which the inside diameter of the cathode is smaller than the inside diameter of the discharge tube 1a in order to limit the resonance region of the laser beam and improve the mode shape. like this
There is a gap in the axial direction, and the corner of the cathode 5a is discharged.
Since it protrudes into the space, the anode side of the cathode 5a, that is, X
1 direction end concentration of the electric field occurs in the glow discharge 14a to the wide discharge tube but was Tsu, even if increasing the current, without spreading over the entire cathode, concentrated on the edge portion of the cathode 5a. Here, the amount of sputter released is substantially proportional to the discharge density in the cathode portion. That is, it is almost proportional to the amount of electric power applied between the electrodes 5a-6a, and almost inversely proportional to the discharge area in the cathode portion. The cathode material, such as nickel sputter, released as sputter in this way is caused to flow downstream by the gas flow circulating at high speed inside the oscillator, and a part thereof adheres to the inner wall surface of the insulating tube 2.

In the apparatus shown in FIG. 3, as the sputter adheres to the inner surface of the insulating tube 2, the insulating characteristics of the insulating tube 2 deteriorate. If the insulation characteristics of the insulating tube 2 deteriorate, abnormal discharge occurs between the cathode 5a and the grounded heat exchanger 10a, and the expected glow discharge cannot be obtained. For this reason, the laser output becomes unstable, and as a result, the laser output decreases.

Further, a part of the sputter adheres to the inner surfaces of the reflecting mirror 7 and the partially transmitting mirror 8 to reduce the laser output. For this reason, it is necessary to periodically repair the insulating tubes 1a, 1b, 2, the reflecting mirror 7, the partially transmitting mirror 8, and the like, resulting in an increase in cost.

As a method for maintaining the insulating properties of the insulating tube 2, it is conceivable to increase the length of the insulating tube 2 in the X direction, but there is a disadvantage that the oscillator becomes large.

SUMMARY OF THE INVENTION An object of the present invention is to provide a high-speed axial-flow type carbon dioxide laser oscillator which has a long maintenance cycle without increasing the size of the oscillator and can minimize a decrease in laser output. It is.

[0009]

According to a first aspect of the present invention, a discharge tube made of an electrically insulating material is provided with an electrode consisting of an anode and a cathode spaced apart in the axial direction, and a high DC voltage is applied between the electrodes. It is applied to a carbon dioxide laser oscillator to be applied. The feature is that the cathode is cylindrical, and a tapered portion is formed at the end of the cylindrical cathode in the anode direction, the diameter of which is reduced in the axial direction of the cathode from the end. And the opening end of the tapered portion of the cathode substantially abuts in the axial direction, and the inside diameter of the end of the discharge tube is formed smaller than the inside diameter of the opening end of the tapered portion of the cathode. This second invention is applied to a carbon dioxide laser oscillator in which electrodes consisting of an anode and a cathode which are spaced apart in the axial direction are arranged on a discharge tube made of an electrically insulating material, and a high DC voltage is applied between the electrodes. . The feature is that the cathode is cylindrical, and a tapered portion is formed at the end of the cylindrical cathode in the anode direction, the diameter of which is reduced in the axial direction of the cathode from the end. The end of the insulating holder made of an electrically insulating material supporting the end of the insulating taper and the opening end of the tapered portion of the cathode substantially abut each other in the axial direction, and the inner diameter of the end of the insulating holder on the cathode side is changed to the opening of the tapered portion of the cathode. That is, it was formed smaller than the inner diameter of the end.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments. FIG. 1 is an enlarged view of a main part of an embodiment of the present invention, and corresponds to FIG. The same components as those in FIG. 4 are denoted by the same reference numerals. In FIG. 1, the cathode 5
the inner diameter of a is smaller than the inner diameter of the discharge tube la, it is formed in a tapered shape whose cross section is enlarged to the anode side, i.e. X ₁ direction. Further, the inner diameter of the opening end of the tapered portion is formed in a cylindrical shape larger than the inner diameter of the holder 13a made of an insulating material.

The operation of the laser oscillator is based on the prior art shown in FIG.
It is similar to the operator, together with the circulating working gas by a blower 9, a high voltage is applied to generate glow discharge between the electrodes 5a-6a and 5b-6b. By the way, as shown in FIG. 2
As shown in, the inner diameter of the tapered end of the cathode 5a is rather smaller than the inner diameter of the holder 13a made of an insulating material,
In addition, since the end of the holder 13a and the end of the cathode 5a have substantially no gap in the axial direction, the electric field concentration at the cathode end is reduced. In addition, the glow discharge 14a is generated by spreading over the tapered portion of the cathode .

That is, the glow discharge 14a is connected to the cathode 5a
Therefore, if attention is paid to the cathode, the discharge density decreases.

As described above, the amount of sputter released is greatly reduced due to the decrease in the discharge density in the cathode portion.
Therefore, the amount of spatter adhering to the inner wall of the insulating tube 2 is
It is significantly reduced. That is, it is possible to prevent the insulation characteristics of the insulating tube 2 from being deteriorated, and it is difficult for abnormal discharge to occur, and the degree of reduction in the laser output becomes extremely gentle.

Of course, when the amount of spatter is remarkably reduced, the repair cycle of the insulating tubes 1a, 1b, 2, the reflecting mirror 7, the partially transmitting mirror 8, and the like becomes longer, so that the repair cost can be reduced. Further, it is not necessary to make the length of the insulating tube 2 in the X direction long, and the laser oscillator can be downsized.

FIG. 2 shows another embodiment of the present invention, in which the discharge tube la is closely contacted with the cathode 5a, and the inner diameter of the opening end of the tapered portion of the cathode 5a is larger than the inner diameter of the discharge tube la. Is formed. Also in this case, the concentration of the electric field at the end of the cathode 5a was reduced, and the glow discharge 14a spread over the tapered portion of the cathode 5a, so that the amount of sputtering could be greatly reduced.

In the above description, the case where the direction of the gas flow is from the anode to the cathode is shown. However, the gas may flow from the cathode to the anode. Further, if the inner diameter of the cathode is larger than the inner diameter of the discharge tube, the mode shape is deteriorated, but it is effective in reducing the amount of sputtering.

[0017]

As is clear from the above description, according to the present invention, the cathodes 5a, 5b
The sputter emitted from the surface of the cylindrical cathode is caused to flow downstream by the gas flow circulating at high speed inside the oscillator, but from the end in the anode direction of the cylindrical cathode, the tapered part which reduces in diameter in the axial direction of the cathode By forming the inner diameter of the discharge tube on the cathode side smaller than the inner diameter of the opening end of the tapered portion, the amount of spatter can be significantly reduced, and the insulation characteristics of the insulating tube can be prevented from deteriorating. Discharge does not easily occur, and the degree of decrease in laser output becomes extremely moderate. Of course,
When the amount of spatter is remarkably reduced, the repair cycle of the insulating tube, the reflecting mirror, the partially transmitting mirror, and the like becomes longer, so that the repair cost can be reduced. Further, it is not necessary to make the length of the insulating tube in the X direction long, and the laser oscillator can be downsized.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a main part of an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part of another embodiment of the present invention.

FIG. 3 is a partial cross-sectional front view showing a conventional example.

FIG. 4 is an enlarged sectional view of a main part of FIG. 3;

[Explanation of symbols]

1a Discharge tube 3a DC high voltage power supply 4a Cathode holder 5a Cathode 6a Anode

Claims (3)

(57) [Scope of request for utility model registration] 1. A carbon dioxide laser oscillator in which a discharge tube made of an electrically insulating material is provided with an electrode consisting of an anode and a cathode spaced apart in an axial direction, and a high DC voltage is applied between the electrodes. Along with the end of the cylindrical cathode in the anode direction, a tapered portion is formed from the end to reduce the diameter in the axial direction of the cathode. The end of the discharge tube and the opening of the tapered portion of the cathode are formed. The end portion is opposed to the axial direction, and the inner diameter of the end portion of the discharge tube is formed smaller than the inner diameter of the open end of the tapered portion of the cathode, so that glow discharge is performed on the cathode.
Carbon dioxide laser oscillator expanded to the tapered part . 2. A carbon dioxide laser oscillator in which a discharge tube made of an electrically insulating material is provided with an electrode consisting of an anode and a cathode spaced apart in the axial direction, and a DC high voltage is applied between the electrodes. The cylindrical cathode is formed on the end side in the anode direction of the cylindrical cathode with a tapered portion which is reduced in diameter in the axial direction of the cathode from the end, and is made of an electrically insulating material for supporting the end of the discharge tube. an open end of the tapered portion of the cathode and the end portion of the insulating holder fit can impact in the axial direction and the inner diameter of the cathode-side end portion of the insulating holder, smaller than the inner diameter of the open end of the tapered portion of the cathode Forming a glow discharge
Carbon dioxide laser oscillator expanded to the tapered part of the cathode . Wherein the inner diameter of the cylindrical portion of the cathode, formed by the size rather than the inner diameter of the discharge tube according to claim 1 or a carbon dioxide gas laser oscillator according to claim 2.