JPS6230716B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates in particular to a three-axis orthogonal discharge excitation circulation type carbon dioxide laser oscillator, and more particularly to a laser oscillation device that improves laser output without increasing the size of the laser oscillator.

The basic principle of a 3-axis orthogonal discharge-excited circulating carbon dioxide laser oscillator (hereinafter simply referred to as a "CO ₂ laser oscillator") is as shown in Figure 1. For example, first and second spherical mirrors 5-1 and 5-
2, and a discharge is generated while a laser gas containing carbon dioxide gas (CO ₂ gas) is flowing at high speed in the direction of the arrow. In the resonance path, the light emitted by the discharge is The light is reflected multiple times between the spherical mirror 5-1 and the second spherical mirror 5-2, so the resonance path length of the light between the output mirror 1 and the rear mirror 3 can be substantially extended. , which aims to improve laser output.

However, since the light is folded back between the first spherical mirror and the second spherical mirror on almost one plane, it is necessary to increase the number of times the light is folded back in order to improve the laser output. However, there is a problem in that the first and second spherical mirrors need to be made larger, which results in an increase in the size of the laser oscillator, and the temperature of the laser gas is lower than that in the CO ₂ laser oscillator. The laser gas tends to rise from the circulation upstream side (solid line arrow in Figure 1) to the circulation downstream side (broken line arrow in Figure 1), and due to the heat caused by the temperature rise,
In particular, if CO ₂ molecules in the discharge region on the downstream side of the circulation are thermally excited to the lower laser level, there is a problem that the population inversion rate in the discharge region decreases, resulting in a decrease in laser output. .

The present invention has been made in view of the above, and its purpose is to improve the laser output of a three-axis orthogonal discharge-excited circulation laser oscillator without enlarging the configuration of the laser oscillator. .

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

Figures 2a and 2b show an embodiment of the invention. First, to explain the configuration of the CO ₂ laser oscillator 7, 9 is a cathode pipe that constitutes a second electrode that is disposed almost on the central axis along the entire length of the laser oscillator 7, and 11 is a carbon fiber-filled cathode pipe. A thin ring-shaped conductor ring 13 (see FIG. 3) molded from epoxy of ring 1
5 (see FIG. 3) and an anode ring (see FIG. 4) constituting the first electrode, which is arranged such that the cathode pipe 9 passes through the ring; 1 and 17-2 are provided in the optical path of the resonator of the CO ₂ laser oscillator 7, which consists of an output mirror 1 and a rear mirror 8 (not shown in FIG. 2a), and as shown in FIG. A ring mirror 19 constitutes a second resonator that three-dimensionally returns the light traveling back and forth between the output mirror 1 and the rear mirror 3 to substantially extend the resonator length.
A laser gas inlet 21 for introducing laser gas containing CO ₂ gas into the laser oscillator 7 is a laser gas exhaust port 21 for exhausting the laser gas introduced from the laser gas inlet 19 and flowing through the laser oscillator 7. The port 23 directs the laser gas to the laser gas exhaust port 2.
1, a shielding plate that leads to the laser beam, 25 a laser tube, 27 an output mirror adjustment section, and 29 a CO ₂ laser oscillator 7.
This is a bracket for attaching to, for example, a machine body or a device. In addition, laser tube 2
A cooling fin 31 is formed in the cooling fin 31 , and the CO ₂ laser oscillator 7 is introduced from the cooling air inlet 33 and guided by the guide plate 35 to the cooling fin 31 .
It is cooled by the air flowing along it.

The cathode pipe 9 is formed of, for example, a water-cooled oxygen-free copper pipe, and the surface of the pipe is coated with aluminum or copper metal by plasma spraying. Note that cooling water or insulating oil is always allowed to flow through the inside of the cathode pipe 9 to cool the inside of the cathode pipe 9 in order to prevent the temperature of CO ₂ molecules from rising, especially during glow discharge.

As shown in FIG. 6, the ring mirrors 17, 17-1, and 17-2 are composed of four segment-shaped spherical mirrors 37 and the same number of segment holes 39, and each spherical mirror 37 is designed to prevent thermal effects. 4 water jackets arranged for
1 is fixed on top. In addition, ring mirror 1
7, 17-1, and 17-2, as shown in FIG. 7, there are two cooling water inlets 43 and two cooling water drains 45.
2 with the cooling water flowing from 3 to the cooling water outlet 45.
Water jackets 41 are cooled.

In operation, the laser gas introduced from the laser gas inlet 19 reaches the laser gas exhaust port 21 through a passage between the cathode pipe 9 and the anode ring 11 or between the anode ring 11 and the laser tube 25. Under such conditions, CO ₂
The laser oscillator 7 applies a high voltage to the laser gas flowing between the cathode pipe 9 and the anode ring 11 to generate a glow discharge, pumps CO ₂ molecules in the laser gas, and outputs an output. Optical amplification is performed by a resonator extending from mirror 1 to rear mirror 3 via ring mirrors 17-1 and 17-2, and when a predetermined threshold value is exceeded, a laser is output.

On the other hand, the anode ring 11 and the laser tube 2
A part of the laser gas that has entered the passage between the cathode pipe 9 and the anode ring 11 passes through the radial groove 15-a formed in the insulating ring 15 and flows into the passage between the cathode pipe 9 and the anode ring 11 to cool the anode ring 11. The cathode pipe 9 and the anode ring 11 The temperature, flow velocity, and density of the laser gas in the ring-shaped glow discharge region between the two are promoted to be uniform, and the CO ₂ molecules in the laser gas are thermally excited to the lower laser level, resulting in population inversion. The decline in rate is suppressed.

Therefore, according to this embodiment, the light between the resonators of the laser oscillator is three-dimensionally folded back by the second resonator in the optical path of the resonator, thereby suppressing the enlargement of the laser oscillator. while increasing the number of turns to extend the resonator length of the laser oscillator, and configuring the anode of the laser oscillator to generate turbulence in the laser gas flowing through the discharge region,
Since the temperature of the laser gas in the discharge region is made uniform, the laser output can be improved without increasing the size of the laser oscillator.

As can be understood from the above description of the embodiments, the gist of the present invention is as set forth in the claims.As is clear from the description, in the present invention, the cooling fins are An annular space through which laser gas can freely pass is formed between the laser tube and a cylindrical first electrode disposed in a laser tube prepared for The ring is made up of alternating layers of conductor rings and insulating rings with radial grooves formed on their end faces. A second electrode is arranged at the axial center of the first electrode, and ring-shaped mirrors are arranged at both ends of the laser tube to three-dimensionally reflect light. It is.

Therefore, according to the present invention, the optical path can be made longer compared to the length of the laser tube, and the overall configuration can be made smaller. Further, the laser gas that has flowed into the laser tube is divided into two systems and flows through the discharge region within the first electrode and the space between the laser tube and the first electrode. The laser gas flowing through the space between the first electrode and the first electrode is cooled and flows into the discharge region surrounded by the first electrode through a radial groove formed in the insulating ring. Therefore, the first electrode is cooled, and at the same time, the laser gas in the discharge region is mixed as fresh, unexcited laser gas, and a swirling flow is generated. Therefore, the temperature of the laser gas in the discharge region is equalized by the population inversion of excited CO ₂ molecules.

Note that the present invention is not limited to the above-described embodiments, but can be modified by making appropriate changes.
Other embodiments may also be implemented.

[Brief explanation of the drawing]

FIG. 1 shows an overview of the principle of a three-axis orthogonal type discharge-excited circulation carbon dioxide laser oscillator, FIGS. Figure 4 is a diagram of the arrangement of the anode ring and cathode pipe, Figure 5 is an overview of the folding of light in the second resonator, Figure 6 is the configuration of the ring mirror, and Figure 7 is a diagram of the cooling method for the ring mirror. shows. (Explanation of symbols representing main parts of the figure), 7...
...CO ₂ laser oscillator, 13 ... Conductor ring, 15
-a... Groove, 15... Insulating ring, 11... Anode ring, 9... Cathode pipe, 17, 17
-1,17-2...Ring mirror.

Claims (1)

[Claims] 1. A cylindrical laser tube 25 with a large number of cooling fins 31 on its outer circumferential surface has a cylindrical shape formed by alternately stacking a thin ring-shaped conductor ring 13 and an insulating ring 15 with radial grooves 15a formed on the end surface. A first electrode is arranged and provided, and an annular space is formed between the first electrode and the laser tube 25 through which the laser gas can freely pass, and the axial center of the first electrode is provided. A second electrode is arranged between the laser tube 25 and the first electrode to generate a discharge, and ring-shaped mirrors are arranged at both ends of the laser tube 25 to three-dimensionally reflect the light. What is claimed is: 1. A laser oscillation device comprising: a laser gas inlet and an inflow/outlet for laser gas;