JPH04372182A - External-mirror-type gas laser oscillator - Google Patents

Abstract

PURPOSE:To provide an external mirror type gas laser oscillator having a long life by preventing the contamination of a Brewster's mirror and a mirror due to the generation of gas from a dustproof cover by ultraviolet irradiation from discharge, CONSTITUTION:The side face of a Brewster's valve 2 is formed of ground glass 10, and the quantity of ultraviolet rays transmitted of the Brewster's valve 2 is reduced. Accordingly, the discharge of gas from fouling adhering on the internal surface of a dustproof cover 7 covering the outside is prevented, thus inhibiting the fouling of a Brewster's window and a mirror.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an external mirror type gas laser oscillator, and more particularly to the structure around the Brewster window of a gas laser tube.

0002

2. Description of the Related Art A conventional dustproof structure between a Brewster window and a laser mirror is shown in FIG. The gas laser tube 4, which ionizes gas such as argon or krypton and generates laser oscillation by its energy transition, has a discharge capillary tube 1 in order to achieve high output.
It is necessary to flow a large current ranging from several amps to several tens of amperes, and as a result, ultraviolet rays are emitted along with oscillated light from the Brewster windows at both ends.

On the other hand, the Brewster window 3 serving as the output window of the gas laser tube 4 is often made of quartz glass in order to minimize loss during laser oscillation. Further, the Brewster window 3 made of quartz glass is sealed to the Brewster bulb 2 made of a quartz glass tube having the same coefficient of thermal expansion via a sealing glass material in order to achieve highly reliable vacuum sealing. The Brewster bulb 2 is sealed to a discharge capillary tube 1 made of ceramic or glass via a discharge capillary end face part 8 made of metal to constitute a gas laser tube 4.

[0004] Also, a gas laser tube 4 constituting an optical resonator
and the laser mirror 5 are held on a support 6 that has the adjustment function necessary to obtain the highest output, and the space between the gas laser tube 4 and the laser mirror 5 is attached to the surface of the laser mirror 5 and the Brewster window 3. It is covered with a dustproof cover 7 made of metal, rubber, or plastic to suppress the inflow of dust and dust that blocks the optical path.

[0005]

[Problems to be Solved by the Invention] In this conventional dust-proof structure between the Brewster window 3 and the laser mirror 5, 200
~400nm ultraviolet light is emitted and passes through the Brewster window 3, Brewster bulb 2 and other glass parts at both ends,
The outside of the gas laser tube 4 is irradiated. At this time, when the metal, rubber, and plastic that make up the dustproof cover 7 are irradiated with ultraviolet rays, the dirt on the material body and surface becomes a gas source, and the gas is released, causing optical parts such as the Brewster window 3 and the laser mirror 5 to be exposed. There was a problem in that it caused surface contamination and resulted in a decrease in output. Furthermore, in many cases, the Brewster window 3 and Brewster bulb 2 are made of quartz glass, which is known for its high transmittance of ultraviolet rays, so the amount of ultraviolet rays transmitted increases compared to other glasses. The problems mentioned above are being promoted.

[0006]

[Means for Solving the Problems] The external mirror type gas laser oscillator of the present invention has a discharge capillary 1, a pair of Brewster bulbs 2 connected to both ends of the discharge capillary 1, and a pair of Brewster bulbs 2 sealed to the tip of the Brewster bulb 2. A gas laser tube 4 consisting of a Brewster window 3, a support 6 that holds the gas laser tube 4 and a pair of laser mirrors 5 for forming an optical resonator on an extension of the gas laser tube 4, and the Brewster window 3. The external mirror type gas laser oscillator 9 includes a dustproof cover 7 for preventing dust between the laser mirror 5 and the laser mirror 5. The external mirror type gas laser oscillator 9 is provided with a Brewster bulb 2 whose side surface is shaped like ground glass.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings. FIG. 1 is a sectional view of the output side portion of an external mirror type gas laser oscillator according to an embodiment of the present invention. Note that the structure of the reflection side portion is basically the same and will therefore be omitted.

In this embodiment, a ground glass portion 10 is provided on the outer peripheral surface of the Brewster bulb 2. Other than this, the configuration is the same as the conventional one.

A large current arc discharge occurs within the discharge capillary 1 between the electrodes 11 at both ends. A portion of the ultraviolet light generated by this discharge spreads in the direction of the optical axis of the laser and passes through the Brewster window 3 and the Brewster bulb 2. Here, the ultraviolet rays incident on the Brewster bulb 2 are reflected and scattered by the microscopic uneven surface of the ground glass portion 10 formed on the outer peripheral surface, and the amount of the ultraviolet rays finally transmitted is sufficiently attenuated. By sufficiently attenuating the ultraviolet rays, generation of impure gas from the dustproof cover 7 can be suppressed. This also seems to be effective in preventing the generation of ozone due to ultraviolet irradiation.

In addition to polishing the ground glass on the outer peripheral surface of the Brewster window 2 with a conventional abrasive, a blasting method has also been considered. In addition, when measuring the transmittance of ultraviolet rays on the surface of ordinary glass and the surface of ground glass, it was found that 200 to 350
Normally 90% or more of the surface in the nm range, 1 to 10% of the ground glass surface
A result of 1.5% has been obtained.

In the embodiment, the outer peripheral surface of the Brewster bulb is shaped like ground glass, but the circumferential surface of the Brewster bulb or both the inner and outer circumferential surfaces may be shaped like ground glass.

0012

As explained above, the present invention reduces the irradiation of ultraviolet rays in the discharge light to the dustproof cover 7 by making the side surface of the Brewster bulb 2 frosted glass, thereby reducing the irradiation of the ultraviolet rays to the dustproof cover 7. This has the effect of preventing contamination of optical components caused by the generated gas, suppressing a decrease in output, and extending the life of the gas laser tube 4 and laser mirror 5.

[Brief explanation of drawings]

FIG. 1 shows a sectional view of an output side of an embodiment of the present invention.

FIG. 2 shows a sectional view of the output side of a conventional dustproof structure.

[Explanation of symbols]

1 Discharge tube 2 Brewster valve 3 Brewster window 4 Gas laser tube 5 Laser mirror 6 Support 7 Dustproof cover 8　　　　Discharge tube end parts 10 Ground glass section 11 Electrode

Claims (4)

[Claims] 1. A gas laser tube comprising a discharge capillary, a pair of Brewster bulbs made of glass connected to both ends of the discharge capillary, and a Brewster window sealed at the tip of the Brewster bulb, and the gas laser Consisting of a support that holds the tube and a pair of laser mirrors for configuring an optical resonator on an extension of the gas laser tube, and a dustproof cover that prevents dust between the Brewster window and the laser mirror. An external mirror type gas laser oscillator characterized in that a side surface of the Brewster bulb has a ground glass shape. 2. The external mirror type gas laser oscillator according to claim 1, wherein the outer circumferential surface of the Brewster bulb has a ground glass shape. 3. The external mirror type gas laser oscillator according to claim 1, wherein the circumferential surface of the Brewster bulb has a ground glass shape. 4. The external mirror type gas laser oscillator according to claim 1, wherein both an outer circumferential surface and an inner circumferential surface of the Brewster bulb have a ground glass shape.