JPH0754862B2 - CO 2 Lower laser oscillator - Google Patents

Description

TECHNICAL FIELD The present invention relates to a CO ₂ laser oscillator for outputting a laser used for industrial purposes such as cutting, welding, heat treatment, etc., and for medical purposes.

_2. Description of the Related Art A conventional CO ₂ laser oscillator of this type will be described with reference to FIG.

In FIG. 4, 1 is a cathode, 2 is an anode, 3 is a total reflection mirror, and 3'is a partial transmission mirror, and these constitute a laser oscillator. 4 is He gas cylinder, 5 is N ₂
Gas cylinder, 6 is a CO ₂ gas cylinder, these He gas cylinder 4, N ₂ gas cylinder 5, He gas supplied from the CO ₂ gas cylinder 6, N ₂ gas, CO ₂ gas is the total reflection mirror 3 and partially transmitted as the laser gas medium It is introduced into the laser oscillator from a supply port near the mirror 3 '. A blower 7 forms a laser gas medium circulation path together with the laser oscillator and circulates the laser gas medium in the laser oscillator. Reference numeral 8 denotes a vacuum pump connected to the circulation path of the laser gas medium, which maintains a constant pressure in the circulation path. The laser gas medium in the circulation path flows in the direction of the arrow in the figure, and in the laser oscillator, the cathode 1
To the anode 2 in the axial direction.

In the above structure, when a DC voltage is applied between the cathode 1 and the anode 2, a discharge is generated in the laser oscillator and a laser output transmitted through the partial transmission mirror 3'is obtained.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the above configuration, not only the discharge is generated between the cathode 1 and the anode 2 in the laser oscillator, but also between the cathode 1 and the total reflection mirror 3 and between the anode 2 and the partial transmission. Electric discharge sometimes occurred between the mirror 3 '. At this time, since the total reflection mirror 3 and the partial transmission mirror 3 ′ act as electrodes, the surface of the total reflection mirror 3 and the partial transmission mirror 3 ′ are severely damaged, the reflectance is lowered, and the laser output is reduced. There was a drawback that it would decrease.

Means for Solving the Problems In order to solve the above problems, the CO ₂ laser oscillation apparatus of the present invention is provided with a first supply port for introducing a part of He gas near the cathode of the laser oscillator, Partially transparent mirror,
A second supply port for introducing a part of N ₂ gas, CO ₂ gas and He gas is provided in the vicinity of the mirror part such as the folding mirror and the total reflection mirror.

Function In the above-mentioned configuration, the quality of the mirror surface is maintained by preventing the discharge in a portion other than between the cathode and the anode in the laser oscillator, the decrease in the laser output is prevented, and the laser power is supplied from the first supply port to the inside of the laser oscillator. The cathode is cooled by the He gas introduced into, improving the stability of the discharge,
Obtain stable laser output.

Embodiments Embodiments of the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 1 is a block diagram of the present embodiment. In FIG. 1, the same components as those shown in FIG. 4 are designated by the same reference numerals and the description thereof will be omitted.

In FIG. 1, reference numeral 9 is a first supply port provided in the vicinity of the cathode 1 of the laser oscillator, and a part of He gas supplied from the He gas cylinder 4 is introduced into the laser oscillator from the first supply port 9. It A second supply port 10 is provided in the vicinity of the total reflection mirror 3 and the partial transmission mirror 3'of the laser oscillator, and is supplied from another part of the He gas supplied from the He gas cylinder 4 and the N ₂ gas cylinder 5. N ₂ gas and CO
_The CO ₂ gas supplied from the ₂ gas cylinder 6 is the second supply port.
It is introduced into the laser oscillator from 10. Reference numeral 11 denotes a third supply port provided in the vicinity of the anode 2 of the laser oscillator, and He gas supplied from the He gas cylinder 4 is introduced into the laser oscillator through the third supply port 11.

In the above structure, when a DC voltage is applied between the cathode 1 and the anode 2, glow discharge is generated between the cathode 1 and the anode 2 in the laser oscillator.

He gas has a cooling effect on the laser medium in He gas, N ₂ gas, and CO ₂ gas, but a part of He gas is introduced into the laser oscillator from the first supply port 9 near the cathode 1. As a result, the cooling effect of the cathode 1 is increased. He gas is N ₂ gas or
It is a gas that discharges more easily than CO ₂ gas and facilitates the maintenance of glow discharge between the cathode 1 and the anode 2. Further, He introduced into the laser oscillator from the second supply port 10
Since the proportion of He gas in the laser gas medium consisting of the other part of the gas and N ₂ gas and CO ₂ gas is small,
The discharge start voltage becomes extremely high, and it is possible to prevent discharge between the cathode 1 and the total reflection mirror 3 and between the anode 2 and the partial transmission mirror 3 '.

In this example, the gas ratio of the laser gas medium was He: N ₂ : CO ₂ = 70: 20: 10, the discharge length between the cathode 1 and the anode 2 was 30 cm, and the distance between the cathode 1 and the total reflection mirror 3 was 30 cm. When the non-discharge length between the anode 2 and the partial transmission mirror 3'is 15 cm, the discharge start voltage was about 20 kV, but in the conventional example, discharge occurred at the non-discharge part during pulse discharge.

As in this embodiment, a part of He gas is introduced from the first supply port 9 in the vicinity of the cathode 1, and the remaining part of He gas and N ₂ gas and
When CO ₂ gas is introduced from the second supply port 10 in the vicinity of the total reflection mirror 3 and the partial transmission mirror 3 ', the discharge generation rate in the non-discharge part and the reduction rate of the laser output after long-term use I checked. The results are shown in FIGS. 2 and 3.

As is clear from FIGS. 3 and 4, by increasing the proportion of He gas introduced from the first supply port 9, the discharge occurrence rate in the non-discharge part during pulse discharge is significantly reduced, and further, The reduction rate of the laser output after using for a long time becomes extremely small.

This is because the cooling effect of the cathode 1 by the He gas is enhanced and the surface oxidation of the cathode 1 is reduced. In particular, both were remarkable when the ratio of He gas introduced from the first supply port 9 was 30% or more.

In the above embodiment, the case where the total reflection mirror 3 and the partial transmission mirror 3'are provided as the mirror portion has been described. However, depending on the configuration of the laser oscillator, the final reflection mirror, the folding mirror or the like may be used as the mirror portion. May be.

As described above, according to the present invention, in the laser gas medium, a part of He gas is introduced into the laser oscillator from the first supply port near the cathode, and the remaining part of He gas and N ₂ gas and By introducing CO ₂ gas into the laser oscillator from the second supply port near the mirror part, the discharge rate in the non-discharge part is reduced, damage to the mirror surface is prevented, and cathode He gas By extending the life of the cathode by cooling
A stable laser output can be obtained for a long time.

[Brief description of drawings]

FIG. 1 is a block circuit diagram of a CO ₂ laser oscillator showing an embodiment of the present invention, and FIG. 2 is a proportion of all He gas in the same CO ₂ laser oscillator supplied from near the cathode and in a non-discharge part. Fig. 3 is a characteristic diagram showing the relationship of the discharge generation rate. Fig. 3 is a characteristic diagram showing the relationship between the ratio of the gas supplied from the vicinity of the cathode in all the He gas in the CO ₂ laser oscillator and the output reduction rate with respect to the initial value. FIG. 11 is a block circuit diagram of a conventional CO ₂ laser oscillator. 1 ... Cathode, 2 ... Anode, 3 ... Total reflection mirror, 3 '...
… Partial transmission mirror, 4 …… He gas cylinder, 5 …… N ₂ gas cylinder, 6 …… CO ₂ gas cylinder, 9 …… First supply port, 10
...... Second supply port.

Claims (3)

[Claims] 1. A partial transmission mirror, a folding mirror, and a total reflection which constitute a resonator of a laser oscillator by providing a first supply port for introducing a part of He gas serving as a laser gas medium near the cathode of the laser oscillator. A CO ₂ laser oscillator comprising a second supply port for introducing another part of N ₂ gas, CO ₂ gas and He gas near the mirror part such as a mirror. _2. The CO ₂ laser oscillator according to claim 1, wherein the flow direction of the laser gas medium is an axial flow direction from the cathode to the anode. 3. The CO ₂ laser oscillator according to claim 1, wherein a part of the He gas introduced from the first supply port is 30% or more of the whole He gas introduced into the laser oscillator.