JPH01146381A - Gas laser apparatus - Google Patents

Abstract

PURPOSE:To obtain a gas laser apparatus effectively prevented from breakdown and capable of outputting stable laser light while minimizing consumption of laser medium gas, by providing a laser light cut-off means between a resonator and aerodynamic windows while providing a mechanical vacuum isolating means in each of the aerodynamic windows. CONSTITUTION:In a gas laser apparatus constructed such that electric discharge is induced within a discharge tube filled with a laser medium to induce laser oscillation and laser light obtained by resonance in a laser resonator is taken out of a laser oscillator, and that the inside of the laser oscillator is isolated under vacuum from the outside by aerodynamic windows 9a, 9b provided with concave mirrors 8a-8d, a laser light cut-off means 6 is provided between the aerodynamic windows 9a and 9b which have mechanical vacuum isolating means 10a and 10b, respectively. When laser is to be radiated, the gas isolation valves 10a, 10b are first opened so that gas is discharged through a gas exhaust port 15 to keep balance of pressure between the atmosphere and the inside of a vacuum vessel 1, and then a light absorbing body 6 is moved out of the optical axis of laser light to ensure an optical path for the laser light.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a high-output gas laser device, and particularly to a laser beam extraction mechanism in a gas laser device where window destruction is a problem. Regarding improved technology.

(Prior art) A gas laser device generates a discharge in a discharge tube filled with a laser medium gas, excites the laser medium gas to cause laser oscillation, and emits the laser output obtained by resonating in a resonator to the outside. This is a device for taking out the material.

FIG. 2 shows a laser beam extraction mechanism of a conventionally used laser device.

In FIG. 2, an unstable resonator consisting of a concave mirror 2 and a convex mirror 3 is constructed in a vacuum chamber 1, and a laser beam obtained from this resonator is transmitted through a window 5 by a resonant coupling mirror 4. It is designed to be taken outside. The window 5 is used here to prevent air from entering the laser medium gas sealed in the vacuum container 1 and to prevent contamination inside.

Furthermore, when the laser beam is not used, a light absorber 6 is inserted into the optical axis of the laser beam taken out from the window 5 to block the laser beam. This insertion operation of the light absorber 6 is automatically performed using a drive device 7.

Incidentally, in recent years, the laser output level has been increasing significantly, and when extracting high-output laser light, even a highly transparent window 6 as shown in FIG. Increasingly, there are cases where the high energy of these materials causes thermal or optical distortion, or destruction due to temperature rise, making them unusable. For example, 15KWC
O2 laser devices have conventionally used windows made of materials such as Zn5e and KC-Ai, but these windows often break during high output, which poses a problem.

In response to this situation, a technology was developed for a laser beam extraction mechanism that can sufficiently handle high-power laser beams.
This is an aerodynamic window as shown in Figure 3.

In FIG. 3, the laser beam extracted by the coupling mirror 4 is irradiated onto the first concave mirror 8a.

In this case, by appropriately setting the mirror curvature of the first concave mirror 8a, the laser beam is focused once and the second concave mirror 8a is focused.
is irradiated onto the concave mirror 8b. Furthermore, by appropriately setting the curvature of this second concave mirror 8b, the laser beam is returned to parallel light beams again. This parallel light beam is then sequentially sent to the third and fourth concave mirrors 8G and 8d, which are similarly set to appropriate curvatures, thereby performing the same laser beam operation.

Here, at the focal points of the first and third concave mirrors 8a and 8c, there are first and second orifices 9a having small pinholes corresponding to the focal points.

9b is provided.

In Fig. 3, 14 is a gas supply port provided on the resonator side, and 15 is a gas exhaust port provided at the center of the aerodynamic window, that is, between the second concave mirror 8b and the third concave mirror 8C. I'll go.

In the laser beam extraction mechanism section of FIG. 3 as described above,
The cavity side is at the sealing pressure of the laser medium gas, that is, almost vacuum pressure, and the laser beam output side is at atmospheric pressure. Therefore, if sufficient exhaust is performed from the gas exhaust port 15, the orifices 9a and 9b provided at two locations will act as flow path resistance, and the pressure coverage between the atmosphere side, the exhaust port section, and the resonator side will be maintained. , it is possible to extract laser light without maintaining a vacuum state. Note that when the laser beam is not used, the light absorber 6 is inserted on the optical axis of the laser beam output from the aerodynamic window.

(Problem to be solved by the invention) By the way, in the gas laser device using an aerodynamic window as described above, unlike the device using a window, there is no risk of destruction, but the pressure balance is maintained by exhausting the scum. As a result, the amount of laser medium gas exhausted from the resonator side also increases, creating a problem in which the amount of laser medium gas consumed becomes large.

The present invention was proposed to solve these problems in the prior art, and its purpose is to extract stable laser light without the risk of destroying the device by using an aerodynamic window. An object of the present invention is to provide an excellent gas laser device that can reduce the amount of laser medium gas consumed as much as possible.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a gas laser device having an aerodynamic window on the output side of a resonator, in which laser light blocking means is provided between the resonator and the aerodynamic window, and A feature of the structure is that a mechanical vacuum cutoff means is provided in the aerodynamic window.

(Function) In the CAST laser device of the present invention having the above configuration, when the laser beam is not used, the laser beam output from the resonator is blocked in front of the aerodynamic window by operating the laser beam blocking means. The amount of gas discharged can be limited by shutting off the laser medium gas inside the aerodynamic window by operating a mechanical vacuum shutoff means.

Therefore, the problem of unnecessarily increasing gas consumption is eliminated.

Furthermore, in the present invention, if a laser output measuring means is provided between the resonator and the laser beam blocking means, the output of the laser beam can be measured even when the laser beam is used.

(Example) The gas laser device of the present invention as explained above was heated at 15K.
An example applied to a WCO2 laser device is shown in FIG. Note that the same parts as those in the prior art shown in FIGS. 2 and 3 are designated by the same reference numerals, and the description thereof will be omitted.

Structure of this embodiment , that energy is converted into an electrical signal. A power monitor signal output from the power sensor 12 is led out of the device via a cable, and is displayed and monitored by a power meter 13.

And between the chopper 11 and the aerodynamic window, a light absorber (
A laser beam shielding means) 6 is provided, and by operating a drive device 7, it is kept at a position offset from the optical axis when the laser beam is used, and inserted on the optical axis when the laser beam is not used. There is.

The laser beam irradiated into the aerodynamic window from the coupling mirror 4 is first focused by a first concave mirror 8a, and a first orifice 9a having a pinhole is provided at the focusing point. A first gas cutoff valve (mechanical vacuum cutoff means) 10a is provided on the laser beam incident side of the first orifice 9a.
is provided. Further, the laser beam focused at this orifice 9a part spreads again and passes through the second concave mirror 8.
b is irradiated and returned to parallel rays.

This parallel light beam is roughly condensed by the third concave mirror 8G, passes through the second orifice 9b, and is used as a parallel light beam by the fourth concave mirror 8d. A second gas cutoff valve 10b is provided on the laser beam incident side of the second orifice 9b to cut off the atmosphere.

Effects of this embodiment* The effects of this embodiment having the above-described configuration are as follows.

That is, when the laser beam is not used, the drive device 7 first inserts the light absorber 6 on the laser optical axis to block the laser beam, so that the aerodynamic window is not irradiated with the laser beam.

After this operation, by closing the first waste cutoff valve 10a provided in the first orifice 9a of the aerodynamic window, the vacuum vessel 1 and the exhaust port 15 are cut off, and the second waste cutoff valve 10a is closed. By closing the second gas cutoff valve 10b provided at the orifice 9b of the
5.

Furthermore, during laser irradiation, the first and second gas cutoff valves 10a and 10b are first opened, and the gas is exhausted from the gas exhaust port 15 so as to maintain the pressure balance between the atmosphere side and the vacuum vessel 1. After that, the light absorber 6 is driven by the driving device 7.
is moved to a position offset from the laser optical axis, the laser optical path is secured, and laser irradiation is performed.

As described above, in this embodiment, by operating the gas cutoff valve when the laser beam is not in use and in atmospheric conditions, the vacuum can be cut off from the atmosphere side and the exhaust port, so that the laser medium gas can be exhausted. It is no longer necessary. That is, compared to the conventional technology in which it was necessary to exhaust the laser medium gas at all times during the operating time, in this embodiment, the exhaust of the laser medium gas to maintain pressure balance can be limited to only during laser irradiation. Gas consumption can be significantly reduced. In this case, the amount of laser medium gas consumed can be reduced in accordance with the usage rate of laser light. For example, in the case of a CO2 laser device for processing, the percentage of laser irradiation time during the operating time is about 30%, so the gas consumption is also 30% compared to the conventional one.
It can be reduced to about %.

In addition, even when the laser is stopped, the gas cutoff valve can shut off the vacuum and the atmosphere, which prevents air from entering the vacuum chamber and reduces internal contamination.

Further, in an emergency, by operating the laser light cutoff device and the gas cutoff device simultaneously, the laser device can be safely and appropriately stopped.

*Other Examples* Note that the present invention is not limited to a gas laser device using an exhaust-type aerodynamic window, but can be similarly applied to gas laser devices having other types of aerodynamic windows, such as a blow-out type or a vortex type. It is.

Further, the laser beam blocking means is not limited to a method of driving a laser beam absorber, but also a means of reflecting the laser beam with a mirror and irradiating it to the laser beam absorber, a means of causing confusion with a distractor, etc. can be used. In other words, any means can be used as long as it prevents the irradiation of the laser beam onto the optical axis that is used and also prevents the irradiation of the laser beam to the valve closed portion when the gas cutoff valve is operated.

Further, as the vacuum cutoff means, it is also possible to provide a gas cutoff gate in a portion other than the orifice portion in addition to providing a cutoff valve in the orifice portion.

However, if a gate is provided at a location other than the orifice,
As the gate size increases, the driving force increases and vacuum sealing becomes more difficult.

On the other hand, as for the laser output measuring means, in addition to the sampling method using a chopper, it is also possible to adopt, for example, a power monitor method combined with a reflective beam shutter mechanism. However, when inserting an optical element such as a beam splitter into the optical axis, there is a risk of destruction.

[Effects of the Invention] As explained above, the gas laser device of the present invention has a simple structure in which the laser light blocking means is provided between the resonator and the aerodynamic window, and the vacuum blocking means is roughly provided inside the aerodynamic window. With this improvement, even in high-output devices, there is no problem of destruction of optical components, and the amount of gas consumed during operation of the laser device can be significantly reduced.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of a gas laser device according to the present invention, FIG. 2 is a sectional view showing a conventional gas laser device using a solid-state window, and FIG. 3 is a sectional view showing a conventional gas laser device using an aerodynamic window. FIG. DESCRIPTION OF SYMBOLS 1... Vacuum container, 2... Concave mirror, 3... Convex mirror, 4... Combined mirror, 5... Window, 6
...Light absorber, 7...Drive device, 8a-8d...
Concave mirror, 9a, 9b...orifice, 10a, 1
0b...Gas cutoff valve, 11...Chopper, 12
... Power sensor, 13... Power meter, 14.
...Gas supply port, gas exhaust port.

Claims (1)

[Claims] (1) A discharge is generated in a discharge tube filled with a laser medium to cause laser oscillation, and the laser beam obtained by resonating in a laser resonator is extracted to the outside of the laser oscillator, and an aerodynamic window using a concave mirror is used to A gas laser device that isolates the vacuum between the laser resonator and the inside of the laser oscillator, the gas laser device comprising a laser beam blocking means between the laser resonator and the aerodynamic window, and using a mechanical vacuum blocking means as the aerodynamic window. . (2) The gas laser device according to claim 1, further comprising a laser output measuring means between the laser resonator and the laser beam blocking means.