JPH03225879A - Gas laser tube - Google Patents

Abstract

PURPOSE:To shorten the passage of laser gas exposed to a discharge part so as to improve laser efficiency by providing a discharge tube with plural supply ports and exhaust ports for gas laser. CONSTITUTION:A discharge tube 14 is provided with plural supply ports 32a and 32b and exhaust ports 33a and 33b for laser gas. And when performing laser oscillation, in addition to the laser gas flowing down from the side of a cathode 13, laser gas is introduced from the plural laser gas supply ports 32a and 32b provided in the discharge tube 14, and these laser gases are mixed, and some of the laser gas being heated by discharge is exhausted quickly from the plural laser gas exhaust ports 33a and 33b provided in the discharge tube 14. Hereby, the distance where the laser gas is exposed to discharge is shortened, and the average temperature of the laser gas is lowered, and the laser efficiency improves.

Description

Detailed Description of the Invention <Industrial Utilization> The present invention relates to a gas laser tube used as a discharge part in a gas laser generator, and in particular to shortening the flow path of laser gas exposed to the discharge part and improving laser efficiency. It has been devised to improve it.

<Prior Art> FIG. 2 shows an example of a gas laser tube used as a discharge section of an axial flow gas laser oscillator.

As shown in the figure, laser gas is introduced into a gas introduction part 12 having a cylinder 10 and a slit 11 therein, where it is made into a swirling flow by the slit 11, and then a ring-shaped cathode 13 is formed.
from this cathode 13 through the discharge tube 14 to a ring-shaped anode 15, where discharge occurs. still,
Reference numeral 16 indicates a gas discharge section.

In this gas laser tube, electrons emitted from the cathode 13 are accelerated by the electric field between the cathode 13 and the anode 15, pass through the discharge tube 14, and reach the anode 15. Here, the laser gas in the discharge tube 14 is excited to the upper level by collision with electrons caused by the discharge between the two poles, and when it relaxes to the lower level, laser light is generated.

An example of an axial flow type gas laser oscillator using the gas laser tube shown in FIG. 2 is shown in FIG. Specifically, this oscillator is
FIG. 2 is a system configuration diagram showing a 02 laser oscillator. As shown in the figure, the output mirror 1001, the folding mirrors 101, 102, and the final stage 103 constitute an optical resonance system.

Note that 104 is a circular optical device that guides the generated laser light. A mixed laser gas of helium, nitrogen, and carbon dioxide gas is supplied into the discharge IfM 14 through a pipe 105 and a cathode 13 in a gas introduction part 12, and the laser gas in the discharge tube 14 passes through an anode 15 and a gas discharge part 16. Then return pipe 1
Flows to 06. In this mixed gas, a discharge is caused between the cathode 13 and the anode 15 to generate excitation of the gas,
The light caused by the laser transition is amplified by the optical resonance, and the laser light is output from the output mirror 100.

The mixed gas is sent from the return)+W1os to the heat exchanger 11107° gas circulation pump 108, and is pumped by the gas circulation pump 108 and flows to the heat exchanger 109° piping 105. The above-mentioned pipe 105 - cathode 13 - discharge tube 14 - anode 15 -
Return pipe 106 → heat exchanger 107 - gas circulation pump 108
→ Heat exchanger 109 → The gas circulation system along piping 105 is called the main circulation system.

On the other hand, a flow rate adjustment valve 111,
It is also supplied to the main circulation system as a mixed gas through the pipe 112. When the mixed gas is supplied to the main circulation system, the same amount of the mixed gas in the main circulation system as the above-mentioned supply amount is supplied to the flow rate adjustment valve 11.
3 to the atmosphere by a vacuum pump 114. Note that 115 is a high voltage power supply, and 116 is a current control circuit.

In the above-mentioned axial flow type gas laser oscillator, it is necessary to increase the population inversion (upper level > lower level) in order to emit a large amount of laser light.At this time, in order to suppress the rise in the temperature of the laser gas, cooling of the laser gas is required. Therefore, conventionally, the discharge tube 14 is cooled from the outside or the laser gas flow inside the discharge tube 14 is made high speed to prevent the average gas temperature from rising.

<Problems to be Solved by the Invention> The cooling of the laser gas described above is performed by the following heat transfer.

(1) Heat transfer between the laser gas and the inner wall of the discharge tube (heat transfer coefficient a) (2) Heat conduction of the discharge tube (heat transfer coefficient a2) (3) Heat transfer between the outer wall of the discharge tube and the external fluid (heat transfer coefficient a,) The overall heat transfer coefficient aT can be expressed by the following formula.

Therefore, the heat transfer coefficient a is aI, α2. It never becomes larger than the minimum value of a3.

Generally, the heat transfer coefficient α is often the minimum, and in this case, there is a limit to cooling the laser gas inside the discharge tube 14 from outside the discharge tube 14, and it is difficult to significantly lower the gas temperature. There's a problem.

Furthermore, as the temperature of the laser gas increases, the lower level component increases, the population inversion becomes saturated, and the laser output that can be extracted reaches its limit.

For this reason, in the past, the temperature of the entire laser gas was significantly lowered to raise the saturation point of population inversion, but in this case, if the temperature is lowered below the ambient temperature, dew condensation will occur on the components of the laser oscillator. . Since high voltage is generally used to generate the discharge, there is a problem in that there is a risk of electrical insulation breakdown due to condensation.

Next, the method of flowing the laser gas at high speed and not raising the gas temperature requires increasing the capacity of the gas circulation pump, which increases the power of the gas circulation pump and has the problem of lowering the overall system efficiency of the laser oscillator.

In view of the above-mentioned circumstances, an object of the present invention is to provide a gas laser tube that can suppress the temperature rise of the laser gas flowing inside the discharge tube of an axial flow type gas laser oscillator and improve the laser efficiency (ratio of laser output/discharge power). shall be.

Means for Solving the Problems> The structure of the laser tube of the present invention to achieve the above object is that a ring-shaped anode and a cathode are respectively disposed at both ends of the discharge tube, and the inside of the discharge tube is A trickle-flow type gas laser tube that performs discharge by causing laser gas to flow down in the axial direction from the cathode side to the anode side, characterized in that the discharge tube is provided with a plurality of laser gas supply ports and discharge ports.

<Function> When performing laser oscillation in the gas laser tube configured as described above, in addition to the laser gas flowing down from the cathode side, laser gas is introduced from a plurality of laser gas supply ports provided in the discharge tube, and these laser gases are mixed. A portion of the laser gas heated by the discharge is quickly discharged from a plurality of laser gas discharge ports provided in the discharge tube, thereby shortening the distance to which the laser gas is exposed to the discharge, thereby lowering the average temperature of the laser gas.

Embodiment Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a structural diagram of a gas laser tube according to this embodiment. Note that the same reference numerals are given to the same members as those in the conventional example described above, and redundant explanation will be omitted. As shown in the figure, a cylinder 1 is provided in the cavity 12a in the gas introduction section 12.
° is installed and an insulating ring 20. One end of the discharge tube 14 is coaxially connected via a ring-shaped cathode 13° insulating ring 21. The other end of the discharge tube 14 is hermetically connected to a ring-shaped anode 15, while the insulating ring 20. IJ ring 11jll! 1
The i13° insulation ring 21 is airtightly attached to the gas introduction part 12 by a support tube 22 surrounding the insulation ring 21.

In addition, a cylinder 10 is provided in the cavity 12a of the gas introduction part 12.
An opening 23 is provided coaxially with the opening 23.
The gas introduction path 24 for introducing the laser gas into the seal 25a
, are airtightly connected by the flange 25 via a seal 25b. In this embodiment, the gas introduction path 24 communicates with an outer tube 27 provided to cover the discharge tube 14 via four branch tubes 26a to 26d. In this embodiment, three collecting pipes 28a to 28
It communicates with a gas exhaust path 29 on the anode side via c.

This gas discharge passage 29 is connected to the gas discharge section 1 by a flange 30.
6 through seals 31a and 31b by a flange 31 in an airtight manner.

In addition, it is covered with the outer pipe 27, and the branch pipe 2
On the wall surface of the discharge tube 14 facing 6a to 26d, there are a plurality of gas supply pores 32a as laser gas supply ports,
32b.

On the wall surface of the discharge tube 14 facing one of the collecting tubes 28a to 28c, there are a plurality of gas exhaust holes 33a, 33b as laser gas exhaust ports.
33c are provided respectively.

Note that a partition plate 27 is provided inside the outer tube 27 to partition the inside of the outer tube.
a to 27f are provided, and the space 1 of the gas introduction section 12
A gas introduction path 24. The laser gas that has passed through the branch pipes 26a to 26d is independently supplied to gas supply pores 32a to 32d provided in the wall of the discharge tube 14.

Further, a part of the introduced laser gas is independently discharged from gas discharge pores 33a to 33c provided in the wall surface of the discharge tube 14 to the collecting tubes 28a to 28c.

This outer tube 27 has one end connected to the support tube 22 attached to the gas introduction part 12 via a seal 34, and the other end connected to the anode 12.
5 through a seal 35 in an airtight manner. Further, the support cylinder 22 is kept airtight with the gas introduction part 12 via a seal 36, and the anode is kept airtight with the gas discharge part 16 via a seal 37.

In this way, the laser gas introduced from the branch pipes 26a to 26d is introduced into the discharge tube 14 through the supply holes 33a to 33d, and a part of the introduced laser gas is again discharged downstream. After the gas is discharged through the pores 33a to 33c to the mating tubes 28a to 28c, the gas discharge part 1
6 and return to the gas circulation path.

Note that the amount of gas flowing from the cathode 13 side through the slit 11 of the gas introduction section 12 and the amount of gas flowing through the gas introduction path 24 through the pore 32a
The ratio of the amount of gas entering from ~32d may be determined by the ratio of the area of the slit 11 of the cylinder 10 and the area of the hole of the pore 32.

By employing a laser tube having such a structure, the laser gas flowing in from the cathode 13 side mixes with the low-temperature laser gas flowing in through the gas supply pores 32a.
A portion of the gas heated by the discharge flows out from the pores 33a. Furthermore, gas flows in through the pores 32b and partially flows out through the pores 33b. At the bottom, part of the gas that has flowed in through the pores 32c flows out from the pores 33c, and the gas that has flowed in through the pores 32d flows out from the anode 15. This allows the average temperature of the laser gas to be lowered, resulting in a significant improvement in laser efficiency.

<Effects of the Invention> As described above in detail together with the embodiments, the gas laser tube according to the present invention has a gas supply hole in the discharge tube as a laser gas supply port, and a gas discharge hole as a laser gas discharge port. By providing multiple holes, low-temperature laser gas flows in from the middle of the discharge tube, and a portion of the laser gas heated by the discharge flows out downstream, thereby suppressing the temperature rise of the laser gas inside the discharge tube. Laser efficiency can be significantly improved.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a gas laser tube according to an embodiment of the present invention, FIG. 2 is a sectional view of a conventional gas laser tube, and FIG. 3 is a structural diagram of a conventional axial flow gas laser oscillator. In the drawing, 10 is a cylinder, 11 is a slit, 12 is a gas introduction part, 13 is a cathode, 14 is a discharge pipe, 15 is an anode, 16 is a gas discharge part, 20, 21 is an insulating ring, 22 is a support tube, 23 is an opening, 24 is a gas introduction path, 25 is a flange, 26a to 26d are branch pipes, 27 is an outer pipe, 27a to 27f are partition plates, 28a to 28d are collecting pipes, 29 is a gas discharge path, 30.31 is A flange, 32a to 32d are gas supply holes, 33a to 33c are gas discharge holes, and 34 and 37 are seals.

Claims (1)

[Claims] In an axial flow type gas laser tube in which a ring-shaped anode and a cathode are disposed at both ends of the discharge tube, and a laser gas is caused to flow down in the axial direction from the cathode side to the anode side inside the discharge tube to generate a discharge, A gas laser tube characterized in that the discharge tube is provided with a plurality of laser gas supply ports and a plurality of discharge ports.