JPS6028284A - Rare gas ion laser tube - Google Patents

Abstract

PURPOSE:To enable to use an easily obtainable and safe material with higher dimension precision by a method wherein plate-shaped metals, each having a small hole in the central part thereof, are mutually connected with an insulator having a larger inside diameter than that of the small hole in a state that vacuum airtightness is being held. CONSTITUTION:Discs 12, which are excellent in heat conduction and thermal stability, consist of an easily obtainable metal plate and respectively have a small plasma generating hole 11 in the central part thereof, are mutually connected with a ceramic disc 14, which has a larger inside diamer 13 than that of the small hole 11 and a smaller outside diameter than that of the disc 12, in such a way that the small holes 11 stand in a straight line in a state that vacuum airtightness is being held, and a fine plasma tube is formed. A laser optical axis 8 is set in the center of the fine plasma tube. The discs 12 are extended to the outside of the vacuum enclosure and each disc 12 acts as a radiating fin as well while holding insulation between its adjoining disc 12. According to this structure, heat, which generates in the small holes 11, is directly radiated by the discs 12. At this time, as the inside diameter 13 of the disc 14 is larger than that of the small hole 11, the disc 14 is hard to receive an ion bombardment and even its ceramic material, which is inferior to a beryllia porcelain in heat characteristics, is hard to be caused damage.

Description

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

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 argon ion laser, the plasma capillary has a narrow inner diameter of 0.8 to 1.2 mm to obtain laser gain, and most of the discharge power is consumed in the plasma capillary.

Therefore, it is necessary to use materials and structures for the plasma capillary that can withstand heat generated from several hundred watts to more than 1 kW. For this reason, the air-cooled argon ion laser tube uses a tube made of an insulator with high thermal conductivity and high heat resistance, such as ceramic porcelain.
This is a structure in which the tube is used as a vacuum envelope, and radiation fins are attached to the outside by brazing or mechanical means, and the radiation fins are forcedly air-cooled.

However, the materials for insulating thin tubes with such thermal and vacuum-tight properties are currently limited to porcelain, and long tubes with good straightness and diameter accuracy of the center hole are available. At the same time, beryllia is difficult to manufacture, and the raw material powder of beryllia is a hazardous substance, which limits production and makes it an extremely expensive substance.

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

That is, the present invention combines a plate-shaped metal having a small hole in the center portion, and an insulator having an inner diameter larger than the small hole in the metal and a smaller outer diameter than the metal. The cooling effect is increased by connecting the metal plates alternately in a straight line while maintaining electrical insulation and vacuum tightness between them to form a plasma capillary, and direct forced air cooling using the metal plates as a heat sink. , a rare gas ion laser tube that makes it possible to use easily available and safe materials other than beryllia porcelain with high dimensional accuracy.

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

A conventional air-cooled rare gas ion laser tube, as shown in the cross-sectional view of FIG. It consists of a blue star 84.4', a return bath 5, and an envelope 6, 6' connected to the beryllia tubule 2 by an enclosure plate 9, 9' made of Kovar metal or the like. A rare gas 7 such as argon is sealed as a laser medium inside the envelope 6° 6' and the beryllia tube 2, and a laser optical axis 8 is set through the center of the beryllia tube 2. Heat radiation fins 10 are attached to the outside of the plasma tube 2 and the anode 3 by 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 heat 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 try to use a ceramic other than Beryllia for the plasma capillary 2, the heat conduction properties of any ceramic are far inferior to Beryllia porcelain, so it is necessary to reduce the thickness of the capillary to improve heat dissipation. It was impossible to construct a laser tube with such strength. For this reason, for air-cooled rare gas ion lasers, plasma capillary materials other than beryllia porcelain could not be considered.

FIG. 2 is a sectional view of the plasma capillary structure of a rare gas ion laser tube showing an embodiment of the present invention. The disk 12 is made of an easily available metal plate with good heat conduction and heat resistance, such as molybdenum, and has a small plasma generation hole 11 in the center.
The small hole 11 also has a larger inner diameter 13, and the small hole 11 is aligned in a straight line by alternating with easily available and harmless ceramic disks 14, such as alumina porcelain, which have a smaller outer diameter than the disk 12 and maintain a vacuum seal by brazing or the like. They are connected to form a plasma capillary, and the laser optical axis 8 is set at the center of the plasma capillary.

The metal disks 12 having a large area extend to the outside of the vacuum envelope and function as heat radiation fins while maintaining insulation between the metal disks.

According to this structure, the heat generated in the plasma thin tube/JX hole 11 is directly radiated to the metal disk 12, which has good heat conduction and also serves as a heat radiation fin. At this time, since the inner diameter 13 of the insulator disk 14 is larger than the inner diameter 11 of the metal disk 12, it is difficult to receive the ion bombardment caused by the large discharge current. Less likely to cause damage. In other words, unlike the conventional structure of the laser tube shown in Figure 1, the heat dissipation fins are not attached outside a vacuum, but the heat generated in the plasma tube is directly dissipated from the heat dissipation fins that form part of the plasma tube. Therefore, the heat dissipation effect is large, the temperature rise of both the metal plate 12 and the insulating tissue 140 made of ceramic or the like is small, and the plasma capillary can be constructed of metals and easily available ceramic materials other than ceramics such as alumina. Of course, if air cooling is used, the plurality of adjacent metal plates 12 will be insulated from each other, and there will be no problem in terms of discharge operation. In this case, the disk 14 made of alumina etc.
The thickness of the small hole 13 may be 2 to 3 nm, and it is easy to obtain the precision of the small hole 13. Needless to say, the dimensional accuracy of the metal plate 120 can be easily obtained in processing.

Further, it is easy to align the insulator disk 14 and the metal plate 12 in a straight line with high precision and braze them simultaneously by extending the conventional electron tube manufacturing technology.

The present invention can be applied not only to an external mirror type laser having a blue meta window, but also to an internal mirror type laser without any problems. Furthermore, the shapes and dimensions of the insulator 14 and the metal plate 12 are not limited. The outer shape of the metal plate 12 may be circular or square.

Further, the thicknesses of the metal 12 and the insulating material 4 can take various values, and are not limited.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a conventional air-cooled rare gas ion laser tube, and FIG. 2 is a sectional view of a plasma capillary tube showing an embodiment of the present invention. l...Cathode, 2...Plasma 7I
+lLl tube, 3...anode, 4,4'...
...Blue meta window, 5...°°・Gas return bus, 6.6'...Vacuum envelope, 7-...Rare gas, 8...Laser Optical axis, 9.9'...-
・Enclosure plate, 10... Radiation fin, 11...
...Metal plate inner diameter, 12...Metal plate, 13...
...Disc-shaped insulator inner diameter, 14...Disc-shaped insulator.

Claims (1)

[Claims] A plate-shaped metal having a small hole in the center and an insulating material having an inner diameter larger than the small hole in the metal and an outer shape smaller than the outer shape of the metal so that the small hole is in a straight line. A rare gas ion laser tube characterized in that the metal plates are alternately connected to each other while maintaining mutual electrical insulation and vacuum tightness to form a plasma thin tube, and the metal plate is used as a heat sink.