JPS6065586A - Rare gas ion laser tube - Google Patents

Abstract

PURPOSE:To obtain a fine plasma tube which can withstand a large discharge current, have good cooling efficiency and dimensional accuracy and ready manufacture by forming small central holes of a metal plate and an insulating plate linearly, providing a gas passage between separate small holes formed at the periphery of the central small holes of both plates. CONSTITUTION:A disc 12 which is made of an insulator that can be readily obtained with good thermal conductivity such as alumina porcelain and has a plasma generating small hole 11 at the center, and a metal plate 14 of large profile larger than the disc 12 having the same as or smaller diameter 13 than the hole 11 are so laminated and connected that the holes 11, 13 are disposed linearly with vacuum airtightness such as brazing to the plate 14, a fine plasma tube is formed with the hore 13 of the plate 14, and a laser optical shaft 8 is provided at the center. Heats generated at the holes 11, 13 of the plasma tube are immediately conducted to the plate 14 having good thermal conductivity, the plate 14 becomes a heat sink fin as it is to dissipate the heat. The heat sink effect is large, and the temperature rise of the insulator 12 approached is small.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rare gas ion laser tube, particularly an argon tube or the like that uses forced air cooling to remove heat generated by a plasma capillary or the like.

In a rare gas ion laser tube, a discharge current ranging from several amperes to more than 10 amperes is passed through the plasma capillary to cause laser transition at the ion level.

In an air-cooled fulbone ion laser, the plasma capillary has an inner diameter of 0.8 to 1.2 m to obtain laser gain, so the voltage drop is large, and most of the discharge power of a rare gas ion laser tube is consumed in the plasma capillary. Ru.

Therefore, it is necessary to use a material for the plasma capillary that can withstand heat generated from several hundred watts to more than 1 kW. For this reason, air-cooled argon ion laser tubes use a tube made of an insulator with high thermal conductivity and high heat resistance, such as beryllia porcelain, and use this as a vacuum envelope. It has a structure that allows forced air cooling.

Furthermore, in order to prevent the filled gas from being unevenly distributed in one side of the laser tube due to a large discharge current, a gas return path connecting the anode portion and the cathode portion is provided separately from the plasma thin tube.

However, the material for insulating capillary tubes with such thermal and vacuum-tight properties is currently limited to beryllia porcelain, which has good straightness and diameter accuracy of the center hole, and is difficult to manufacture in long lengths. In addition to being difficult to produce, beryllia porcelain is a toxic material, limited in production, and extremely expensive.

Moreover, the gas return path provided externally complicates the structure of the rare gas ion laser tube, requires skilled glass processing, and there is a great risk of damage when the laser tube is assembled.

A conventional air-cooled rare gas ion laser tube, as shown in the cross-sectional view of FIG.
, anode 3, a pair of blue metal windows, 1.4',
A return path 5 and an enclosure plate 9 made of cover metal etc.
, 9' to the beryllia porcelain capillary tube 2. A rare gas 7 such as argon is sealed as a laser medium inside the envelopes 5, 5' and the porcelain thin tube 2, and a laser optical axis 8 is set through the center of the beryllia porcelain thin tube 2. A heat dissipation fin 10 is attached to the outside of the plasma tube 2 and the anode 3 with brazing or screws, and heat generated in the plasma tube and the anode is removed by a fan (not shown).

Since the plasma thin tube 2 is made of beryllia porcelain with good thermal conductivity, the generated heat is quickly radiated through the radiation fins 10. However, beryllia porcelain is expensive and harmful, and it is difficult to obtain long thin tubes with good straightness and a highly accurate inner diameter of the small holes. If you wish to use a ceramic other than Beryllia porcelain for the plasma capillary tube 2, most easily available ceramics have far inferior heat conductivity properties than Beryllium porcelain, so it is recommended to reduce the thickness of the capillary tube to improve heat dissipation. It was impossible to construct a laser tube with practical surface strength. Therefore, for air-cooled rare gas ion lasers, plasma capillary materials other than Berria porcelain could not be considered.

Furthermore, as shown in Fig. 1, a gas return path 5 must be provided outside the plasma thin tube 2, which requires glass processing that requires skill, and is also handled as a laser tube, so there is a high risk of breakage when installing the tube. Ta.

An object of the present invention is to provide a rare gas ion laser tube having a plasma capillary that can withstand large discharge currents, has good cooling efficiency and dimensional accuracy, and is easy to obtain and manufacture.

Another object of the present invention is to provide a rare gas ion laser tube that has a gas return path structure in the plasma thin tube portion, has no external gas return path, and is mechanically easy to handle.

The present invention will be explained below with reference to the drawings.

FIG. 2 is a cross-sectional view in the optical axis direction of a plasma capillary structure of a rare gas ion laser tube showing an embodiment of the present invention, and FIG. 3 is a cross-sectional view in the radial direction.

The disk 12 is made of an easily available and harmless insulator with relatively good thermal conductivity such as alumina porcelain, and has a small plasma generating hole 11 in the center, and an inner diameter 13 that is the same as or smaller than the small hole 11. The metal plates 14 having an outer diameter larger than the outer diameter of the metal plates 12 are stacked and connected by brazing or the like alternately so that the small holes 11 and 13 are aligned in a straight line while maintaining vacuum tightness, so that the inner diameter 13 of the metal plate 14 is the main As a result, a plasma thin tube is formed, and the laser optical axis 8 is set at the center of the plasma thin tube. At this time, in addition to the small hole 11 at the center, the disk 12 is provided with one or more small holes 14a to 14d around it, and the metal plate 14 has small holes at positions corresponding to the small holes 14a to 14d, for example. Holes 15a-15d are provided. Small holes 14a-1
4d or small holes 15a to 15a are respectively small holes 1
The anode 3 and cathode 1
The funductance between the gas flow and the electricity is set to be sufficiently small so that the discharge between the small holes 1], , 13 and 143 to 14d and 15a to 15d does not occur. Therefore, the small holes 14a to 14d.

No discharge occurs in 15a-15d, but the filler gas can flow freely. Metal plate 14 with a large external shape
constitutes a plasma thin tube, and at the same time extends to the outside of the vacuum envelope and serves as a heat dissipation fin while maintaining electrical insulation between the metal plates.

According to this structure, the heat generated in the plasma capillary small holes 11, 13 is immediately conducted to the metal plate 14, which has good thermal conductivity, and the metal plate 14 acts as a heat radiation fin and radiates the heat.

When the inner diameter of the small hole 13 is smaller than the inner diameter of the small hole 14, the center part 13 of the metal plate 14 mainly plays the role of a plasma capillary, but since the generated heat is directly forced air cooled, the temperature rise is extremely small and there is no spatter. small. In other words, unlike the conventional laser tube structure shown in Figure 1, the heat dissipation fins are not indirectly attached outside the vacuum, and the generated heat is dissipated through the metal itself at the location where it is generated, resulting in a large heat dissipation effect. Since the temperature rise of the insulator 12 is also small, it is possible to use a material such as alumina, which has a lower thermal conductivity than the bare IJA. Of course, if used with air cooling, multiple adjacent metal plates 1
4. That is, the metal plasma capillary tubes are insulated from each other, and there is no problem in terms of discharge operation.

The trenches 14a to 14d and 15a to 15d serve as gas return paths, and a simple and durable structure is achieved without requiring any special gas return path outside the plasma capillary. In this case, the disk 12 made of alumina porcelain etc.
may have a thickness of 2 to 31++II+, and the metal plate 14
It has less restrictions on dimensional accuracy than the inner diameter 13 of the inner diameter 13, and a desired shape can be easily obtained.

Further, it is possible to align the insulating disk 12 and the metal plate 14 with high accuracy and vacuum-tightly braze them at the same time by extending the conventional electron tube manufacturing technology.

The small holes 14a to 14d, 15a to 15d only need to allow the laser medium gas to pass through them, so high dimensional accuracy is not required and linearity is not strongly required. Small holes 14a to 14d and 15a
The inner diameter dimensions of the holes 153 to 15d may not be the same, and the small holes 153 to 15d in the outer metal plate 14 may be made small and the small holes 142 to 15d in the insulator 15 may be made large so that fine processing is easy.

That is, the small holes 14a-14d, 15a-15d can be arbitrarily selected in shape, number, and arrangement as long as no discharge occurs.

The present invention is applicable not only to external mirror type lasers with a blue meta window but also to internal mirror type lasers. Insulator 12. The shape and dimensions of the metal plate 14 are not limited. metal plate 1
The outer shape of the insulator 4 may be circular or square, and the thicknesses of the insulator 12 and the metal plate 14 are not limited by the present invention.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a conventional air-cooled rare gas ion laser tube, FIG. 2 is a sectional view along the optical axis of a plasma capillary according to an embodiment of the present invention, and FIG. 3 is a radial sectional view. ■...Cathode, 2...Plasma tube, 3...Anode, 4.4'...Blue metal window, 5...Gas return Pass, 6.6'
−゛°°°Vacuum envelope, 7...Rare gas, 8...
...Laser optical axis, 9,9', old...Enclosure dish, 10
...Radiation fin, 11...Disc-shaped insulator inner diameter, 12...Disc-shaped insulator, 13. Old...
Metal plate inner diameter, 14...°°°Metal plate% 14a~14
d...Insulator small hole for return path, 15a-1
5d... Metal plate small hole for return bus.

Claims (1)

[Claims] A plate-shaped metal plate having one small hole A provided in the center and one or more other small holes B provided around the small hole, and the size of the small hole A or larger. a small hole C and an insulating plate having one or more small holes provided around the small hole C and having an outer shape smaller than the outer shape of the metal plate, so that the small holes A and C are in a straight line. The small holes B and D are connected alternately so that a gas passage is formed, and while maintaining electrical insulation and vacuum tightness between the metal plates, forming a plasma thin tube. Rare gas ion laser tube.