JPS59222983A - Sealing method of optical part for laser tube - Google Patents

Abstract

PURPOSE:To prevent a diffusion to a non-sealing section of melted indium, and to obviate the damage of optical characteristics by previously mounting a material generating no wetting property to indium to a boundary between a sealing section and the non-sealing section. CONSTITUTION:PbF2 is evaporated previously in a ring-shaped region of a radius of 9-10.5mm. from the center in approximately 0.2-0.3mum thickness as an indium diffusion preventive material 8 on a sealing surface 7 for an optical part 6. Even when an indium diffusion preventive material 8 section covers a laser oscillation region 9, heat is hardly generated by laser beams, and the optical part 6 can be kept without a thermal damage. An indium wire 10 is fast stuck to the outer circumference of the sealing section and encircles it, and a closed loop is formed. The inside of a sealing chamber 1 is evacuated, and high-frequency induced currents are flowed through a laser tube sealing surface 5, the optical part 6 for a laser and the indium wire 10 by a high-frequency induction coil 11 to heat them. Currents flowing through the high-frequency induction coil 11 are controlled at that time, and the optical part is sealed. There are ThF4, NaF, As2S3, etc. besides PbF2 as a material generating no wetting property to indium.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for sealing optical parts of a laser tube, in which optical parts are sealed to the end of a laser tube.

Conventional structure and problems Conventionally, in the production of sealed gas laser tubes, the end of the laser tube and optical components such as laser beam reflectors are sealed using epoxy adhesive or low melting point glass. The fusion was carried out by The former is essentially unsuitable for extending the lifespan and improving the reliability of the laser tube because of the release of impurity gas from the adhesive and the presence of gas leaks. In addition, the latter has the disadvantage that the thermal expansion coefficient of the low-melting glass must match that of the laser tube and optical components, so the laser tube must be constructed from a very limited number of materials. .

Recently, a new method for sealing optical components of a laser tube that overcomes the above-mentioned drawbacks has been developed and is about to be put into practical use. The new sealing method uses indium, which is known as a low melting point metal material, as the sealing material, and seals by forming an alloy between the sealing base material and indium. In this sealing method, molten indium permeates into the sealing part by capillary action and forms a strong alloy with the sealing base material, making it possible to increase the sealing cross-sectional area. Furthermore, since there is no generation of impurity gas from the sealed portion that would interfere with the laser oscillation operation, it is possible to extend the life of the laser tube and improve its reliability. Furthermore, due to the large ductility of indium-based alloys, mismatches in thermal expansion coefficients between the laser tube and optical components can be accommodated, allowing for free combinations of these materials. Moreover, since the thickness of the sealing layer can be made as thin as about s7zm, it also has the advantage of being less susceptible to thermal fluctuations in the laser tube length.

However, in this sealing method, the sealing base material must be a feed that can form an alloy with indium, so the molten indium forms an alloy by capillary action without any limit, and the sealing base material is bonded to the base material. The gold can be freely diffused and the sealed area cannot be controlled.

When the indium-based alloy layer diffuses outside the sealing region, it significantly disturbs the optical characteristics of the optical component, resulting in a decrease in laser oscillation output and a disadvantage that the laser output oscillation mode becomes non-uniform.

OBJECTS OF THE INVENTION The present invention overcomes the above-mentioned disadvantages of the prior art by using the sealing technique described above and limiting the diffusion of molten indium into the unsealed areas, thereby avoiding any optical damage. The object of the present invention is to provide a method for sealing an end of a laser tube and an optical component.

Structure of the Invention The present invention achieves all of the above objects by using indium gold as the sealing material when sealing the end of the laser tube and the optical component, and by forming the entire innoum alloy layer between the two. When performing this process, the boundary between the sealed part and the non-sealed part is coated with a material that does not produce wettability with indium, and the sealing area is controlled. All that is offered.

Description of examples The present invention will be described in detail below with reference to the drawings.

FIG. 1 shows the vicinity of the sealing jig and the sealing section. In carrying out this sealing method, the sealing portion was heated by high frequency induction heating, and only the sealing portion was selectively heated. Furthermore, if indium is oxidized when melted, it will not be possible to fully form an alloy with the sealing base material, so the sealing chamber 1 made of stainless steel can be evacuated through the vacuum exhaust port 2. The progress of sealing can be observed from the outside through an observation window 3 made of quartz glass. The laser tube 4 made of heat-resistant glass has an inner diameter of 18ffff and an outer diameter of 28 mm, and the end face of the double-tube Tsuquib is entirely sealed.The laser tube sealing surface 6 is mirror-polished and then coated with 0.2 to 0.0 mm of gold. It was deposited at a speed of 4 μm. This is because heat-resistant glass and indium cannot form an alloy, so gold is attached. In this embodiment, the laser optical component 6 is made of gold 14 f O- on a copper substrate 13, which is a typical total reflection mirror for a carbon dioxide laser.
2~0.3 Its evaporated diameter 26゜4㎜ (11nc
hφ) and a thickness of 5 mm was used. On the sealing surface 7 of this optical component 6.

PbF2Q thickness 0.2 as an indium diffusion prevention material 8 in a ring-shaped area with a radius of 9 to 10.5 am from the center.
~Q, 3/1m vapor deposition. The material PbF2 not only has no wettability for indium, but also
The absorption coefficient at the oscillation wavelength of the carbon dioxide laser is 2.6
It is as small as 10""cm-'. Therefore, even if the portion of the indium diffusion prevention material 8 touches the laser oscillation region 9, the amount of heat generated by the laser beam is small, and the optical component e can be kept free from thermal damage. Indium as a sealing agent is an indium wire 10'li7 with a diameter of 0.5πm and a purity of 99% or more. As shown in Fig. 1, the indium wire 1o is tightly wrapped around the outer periphery of the sealing part.
Form a closed loop. Next, inside the sealing chamber 1 11o
After evacuation to a temperature below Torr 1, the high frequency induction coil 11 is evacuated and the laser tube sealing surface 5. A high frequency induced current is applied to the laser optical component 6 and the indium wire 10 to heat them. At this time, while monitoring the temperature of the sealed part with the pyrodetector 12 through the entire observation window 3, the electric current flowing through the high frequency induction coil 11Vc is polished so that the temperature of the sealed part is constant at 250°C. I did the sealing.

At the same time, in order to increase the effectiveness of this example, sealing was performed even when no coating was applied on the boundary between the sealed and non-sealed parts of the optical component 6, and all comparisons with this example were made. went. FIG. 2 shows the state of the optical component sealing surface after sealing. Second
Figure (&) shows the case where nothing is coated on the boundary between the sealed part 15 and the non-sealed part 16, and Figure (b) shows the case where the boundary part is coated with the diffusion preventive agent 8 made of PbF2. be.

In the case of (&), it can be seen that the indium alloy layer 17 diffuses freely and flows into the non-sealed portion 16 as well. However, as is clear from Figure (b) showing this example, in this case, the indium alloy layer diffused only in the sealed portion 15, and no flow into the non-sealed portion 16 was observed. Also,
As a result of measuring the amount of vacuum leak from the sealing part using a helium detector, the helium leak rate was 10 x 1 for both.
It was confirmed that there was no vacuum leak at all, with a QC of 0 atm QC of 7 seconds or less.

As described above, the method for sealing optical components of a laser tube according to the present invention makes it possible to completely seal the end of the laser tube and the optical components without damaging the optical properties. In this example, the explanation was limited to PbF2 as an indium diffusion inhibitor, but this inhibitor can essentially be any material that does not produce wettability with indium, and there are many other materials that can be used. Ru. For example, ThF4. NaF, )J2S
5 etc. In addition, if the evaporation width of indium diffusion barrier d=-+a (rho/ts mm or more), it is sufficient for practical use.

Effects of the Invention As described above, when sealing an optical component to the end of a laser tube using indium, the present invention prevents wetting with indium from occurring in advance at the boundary between the sealed part and the non-sealed part. Diffusion of molten indium into the unsealed area, fK
: It has the advantage that it can be sealed without damaging the optical properties.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a main part showing an embodiment of the present invention, and Fig. 2 is a cross-sectional view showing a sealing surface of an optical component after sealing. ) is provided. 1... Sealing channel <-, 2... Vacuum material I
Air port, 3...Observation window, 4...Laser tube,
5... Adhesion surface of the laser tube, 6... Optical components,
7...Sealing surface for 13 optical products, 8...Indium diffusion prevention material, 9...Ra → ノ' emission 1 area, 1o...Indium Wire, 11...
High J? 6-wave induction coil, 12...No; Color detection 2i, 13...Copper substrate, 14...Gold vapor deposited film, 16...Sealing 91 (, 16...Unsealed portion, 17...Indium alloy layer. Name of agent Patent attorney Toshi Nakao Male -1 or 1 person Figure 1 2 Figure 2 (excerpt) 2

Claims (1)

[Claims] When sealing the end of the laser tube using original all-indium, the indium sealing is performed after providing a material that does not wettability with indium at the boundary between the sealed and non-sealed parts. A method for sealing optical components in laser tubes.