JPH02163987A - Gas laser oscillation apparatus - Google Patents

Abstract

PURPOSE:To keep a gas temperature constant by using a heat exchanger and to remove impurities such as dust particles or the like in a laser medium gas by installing a filter by a method wherein the laser medium gas is circulated forcibly in a laser tube in order to suppress a rise in the gas temperature in a crossing part, of laser beams, where the Raman transform is executed. CONSTITUTION:When a laser beam is incident on the inside of a laser tube 11 through an input tube 14, it is reflected several hundred times by reflectors 12, 13 and is taken out to the outside from an output tube 15. In this case, when the laser beam is reflected by the reflectors 12, 13, an angle of the input tube 14, a shape of the reflectors 12, 13 and an angle of the output tube 15 are decided in such a way that laser beams are crossed mutually in the central part of the laser tube 11. Since dust particles are trapped by using a filter 20, it is possible to prevent the dust particles whirled from a structure by a flow of a laser medium gas from flowing into the laser tube 11. Even when a light path is very long, it is possible to prevent an efficiency of the laser beam from being lowered when the laser beam is absorbed by the dust particles. In addition, the laser medium gas in a part where the laser beams are crossed and the Raman transform is executed is always replaced; accordingly, it is possible to prevent a temperature rise by using a heat exchanger 19; this apparatus can resist the continuous Raman transform.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a gas laser oscillation device in which Raman conversion is performed.

(Prior Art) Conventionally, in this type of gas laser oscillation device, two reflecting mirrors 2 are arranged opposite to each other on both end surfaces of a laser tube 1 in which a laser medium gas is sealed, as shown in FIG. At the same time, an input tube 3 and a window 4 are provided at one end of the laser tube 1 to output the laser beam, and an output tube 5 and a window 6 are provided at the other end to output the converted laser beam. The laser beam A entering from the tube 3 is made to go back and forth several times between the two reflecting mirrors 2, and the wavelength of the laser beam is converted by performing Raman conversion at the mutual intersection, and the wavelength of the laser beam B is changed. is taken out to the outside via an output tube.

(Problem to be Solved by the Invention) By the way, in this type of gas laser oscillation device, the conversion efficiency of Raman conversion performed at the intersection of laser beams is several 10% at most, and the gas temperature at the intersection after conversion is It will rise accordingly. In this case, if pulsed light is incident and Raman conversion is performed only once at a certain moment, the rise in gas temperature will not be a problem, but if continuous or pulse-shaped laser light is repeatedly incident. As a result, the gas temperature at the cross-sealing portion increases rapidly and eventually turns into plasma, making it impossible to perform Raman conversion.

Further, even if the gas does not become plasma, the rise in gas temperature may create a strong dense state in the gas, preventing the laser light from passing through a predetermined optical path, making it impossible to extract the laser light. To solve this problem, you can keep the gas temperature from rising by supplying new gas to the intersection by flowing the gas, but if you move the gas, dust will inevitably rise. . In this type of gas laser oscillation device, the light at the intersection of the laser beams is very strong, so if dust is present in this area, the dust turns into plasma and inhibits Raman conversion. Furthermore, since this type of gas laser oscillation device has a very long optical path, if there is dust, the effect of light absorption by the dust will be large.
The efficiency of the device becomes very poor.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a gas laser oscillation device that can prevent temperature rise at the intersection of laser beams and improve Raman conversion efficiency.

[Structure of the Invention] (Means for Solving the Problems) The present invention includes a gas circulation means for forcibly circulating a laser medium gas sealed in a laser tube, and a filter for removing impurities in the gas. .

(Function) By forcing the laser medium gas to circulate through the laser tube, the rise in gas temperature at the intersection of the laser beams where Raman conversion is performed is suppressed, and the gas temperature is kept constant by the heat exchanger. Further, by providing a filter, impurities such as dust in the gas are removed and the laser optical path is kept in a clean state, thereby making it possible to maintain high Raman conversion efficiency.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 11 denotes a laser tube in which a laser medium gas is sealed.
Two reflecting mirrors 12 and 13 are arranged. These reflectors 1
2.13 has a hole in each part, and the reflecting mirror 12
An output tube 15 from which a laser beam is output is connected to a human-powered tube 142 to which a laser beam is manually input and a reflecting mirror 13.

The laser tube 11 is provided with an air supply pipe 16 for supplying laser medium gas at the end having the manual tube 14, and an exhaust pipe 17 for exhausting the laser medium at the end having the output pipe 15.

A blower 18. A heat exchanger 19 and a filter 20 are provided.

Here, the blower 18 is for forcibly circulating the laser medium gas in the laser tube 11.

Further, the heat exchanger 19 is for keeping the gas temperature constant, and the filter 20 is for removing impurities such as dust in the gas.

When the laser beam is now incident on the inside of the laser tube 1.1 through the input tube 14, it is reflected several hundred times by the reflecting mirrors 12 and 13, and then is taken out from the output tube 15. In this case, the input tube 1 is arranged so that the laser beams cross each other at the center of the laser tube 11 when reflected by the reflecting mirrors 12 and 13.
4, the shape of the reflector 12, 13, and the angle of the output tube 15 are determined. At the intersection of the laser beams, Raman conversion is performed by the action of the laser medium gas, and the wavelength of the laser beam changes to a value specific to the laser medium gas. In this case, since the efficiency of Raman conversion is not 100%, the temperature of the laser medium gas after conversion increases by the amount of loss. However, since the laser medium gas in the laser tube 11 is forcibly circulated in the direction of the arrow shown in the figure by the blower 18, the heated gas quickly flows away from the part where the laser beams intersect with each other, and passes through the exhaust pipe 17 to release heat. The temperature of the laser medium gas at this time is given to the heat exchanger 19.
9 keeps it constant.

Further, when the laser medium gas is moved, dust flies up and circulates together with the gas, but this dust is trapped by the filter 20. In this state, the laser medium gas is again supplied into the laser tube 11 from the air supply pipe 16, and the same operation is repeated thereafter.

According to this embodiment, since dust is trapped in the filter 20, the dust kicked up from the structure by the laser medium gas flow can be prevented from flowing into the laser tube 11, and the laser optical path can be kept clean. can. As a result, even in this type of gas laser oscillation device having a very long optical path length, it is possible to prevent the efficiency from decreasing due to absorption of laser light by dust. Furthermore, since the laser medium gas in the portion where the laser beams intersect and Raman conversion is performed is always replaced, temperature rise in this portion can be prevented and continuous Raman conversion can be endured. Further, dust is not turned into plasma by the laser beam in the area where the conversion is performed, and the cause of inhibiting the Raman conversion can also be eliminated.

Next, FIG. 2 shows another embodiment of the present invention.
The same parts as those in the figure are given the same reference numerals.

In this embodiment, an annular flow path 21 is provided on the input pipe 14 side of the laser tube 11, and a filter 22 having the same inner diameter as the laser tube 11 is provided within the annular flow path 21. This annular flow path 21
An air supply pipe 16 is connected to. In addition, the laser tube 11
A disk-shaped exhaust path 23 and an annular flow path 24 connected thereto are installed on the output pipe 15 side. An exhaust pipe 17 is connected to the annular flow path 24 . and exhaust pipe 1
A blower 18 and a heat exchanger 19 are installed between the air supply pipe 7 and the air supply pipe 16.

In this way, the filter 22 is supplied with laser medium gas from the outer circumferential side in the direction of the arrow in the figure through the annular flow path 21. In this case, since the filter 22 has resistance, the laser medium gas flows into the laser tube 11 so as to uniformly seep out from the inner peripheral side of the filter 22.

The inflowing laser medium gas flows toward the output tube 15 side and collides with the reflecting mirror 13. The colliding laser medium gas spreads along the reflection m13 in the direction of the arrow and flows into the disk-shaped exhaust path 23. Then, the laser medium gas enters the annular flow path 24 through the exhaust path 23, is collected in the exhaust pipe 17, and is collected in the heat exchanger 19. The air passes through the blower 18° filter 22 and flows into the laser tube 11 again. Filter 2 in this case
In addition to the function of trapping dust, the function of 2 is to allow the laser medium gas to flow into the laser tube without disturbing the flow.

The exhaust passage 23 on the opposite side also has the function of causing the laser medium gas to flow out of the laser tube 11 without disturbing the flow.

According to this embodiment, turbulence in the laser medium gas flow inside the laser tube 11 can be made very small.

This means that when the intensity of the incident laser light is high and it is necessary to flow the laser medium gas at high speed, unevenness will inevitably occur due to the flow of the laser medium gas, but in this example, the unevenness of the laser medium gas is minimized. can be suppressed to
This makes it possible to prevent the quality of the laser beam from deteriorating due to the density of the laser medium gas.

Next, FIG. 3 shows another embodiment of the present invention, in which the same parts as in FIG. 1 are given the same reference numerals. In this embodiment, a disk-shaped air supply path 2 is provided on the input tube 14 side of the laser tube 11.
5 is installed, and an annular flow path 26 is connected to this air supply path 25. The air supply pipe 16 is connected to the annular flow path 26 . In addition, a disk-shaped exhaust passage 2 is provided on the output pipe 15 side at the other end.
7 and an annular flow path 28 connected thereto. The exhaust pipe 17 is connected to the annular flow path 28 . A blower 18 is provided between the exhaust pipe 17 and the air supply pipe 16.
and heat exchanger19. A filter 20 is installed.

In this way, the disk-shaped air supply path 25 receives the laser medium gas supplied from the outer circumferential side in the direction of the arrow in the figure through the annular flow path 26. In this case, the inner periphery of the disk-shaped air supply path 25 is widened, and the laser medium gas flows into the laser tube without causing disturbance. The inflowing laser medium gas flows toward the output ff1511111 and collides with the reflecting mirror 13. The colliding laser medium gas spreads along the reflecting mirror 13 in the direction of the arrow and flows into the disk-shaped exhaust path 27. The laser medium gas enters the annular flow path 28 through the exhaust pipe 27, is collected in the exhaust pipe 17, and is collected in the heat exchanger 19. Blower18. It passes through the filter 20 and flows into the laser tube 11 again.

This embodiment also allows the turbulence of the gas inside the laser tube to be extremely small, and even when it is necessary to flow the laser medium gas at high speed, it is possible to minimize the occurrence of fl density caused by the flow of the laser medium gas. Therefore, deterioration in the quality of the laser light due to the density of the laser medium gas can be suppressed.

[Effects of the Invention] By forcibly circulating the laser medium gas through the laser tube, the present invention can prevent a temperature rise at the intersection of laser beams, and by providing a filter, a clean state can be maintained on the laser optical path. The Raman conversion efficiency can also be improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of a gas laser oscillation device according to the present invention, FIGS. 2 and 3 are sectional views showing other embodiments of the present invention, and FIG. 4 is a sectional view of a conventional gas laser oscillation device. It is a sectional view showing an example. 11...Laser tube, 12.13...Reflector, 14.
...Input pipe, 15...Output pipe, 16.25...Air supply pipe, 1.7.23...Exhaust pipe, 18...Blower, 1
9... Heat exchanger, 20... Filter 22...
Filter 21゜24゜26... annular flow path.

Claims (1)

[Claims] Two reflecting mirrors facing each other are placed inside the laser tube filled with laser medium gas, and the laser light introduced into the laser tube is reflected back and forth between the reflecting mirrors to output Raman-converted laser light. The gas laser oscillation device is equipped with a gas circulation means for forcibly circulating the laser medium gas inside the laser tube, and a filter for removing impurities in the laser medium gas circulated by the gas circulation means. A gas laser oscillation device characterized by: