JP2000340863A - Laser device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of the performance of laser windows, which is to be caused by contaminant by preventing stagnation of contaminated laser medium on the inner surface of the laser windows. SOLUTION: Clean laser medium gas from a piping 73 arranged on a window holder 3 is branched into a pair of ports 32a, 32b and supplied to an inner space of the window holder 3. The laser medium gas, which is spouted into a shield chamber SC from the first port 32a proceeds to the second port 32c along laser windows 4 and fed back to the inside of a vessel 2 having a more negative pressure. Since the first port 32a is arranged almost facing a second port 32c, the clean laser medium gas from the first port 32a flows as a laminar flow almost along the inside surfaces of the respective laser windows. Thereby the clean laser medium gas is always supplied to the vicinities of the inside surfaces of the laser windows 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser device using a gaseous laser medium, and more particularly to a laser device of a type that circulates a gaseous medium.

[0002]

2. Description of the Related Art In a gas laser, a resonator mirror may be arranged outside a container containing a laser medium. In this case, a pair of laser windows is provided at a position facing the container that stores the laser medium, and the resonance mirrors are respectively disposed to face these laser windows.

[0003] With respect to this laser window, it is considered that contaminants are accumulated in the laser medium due to reaction or discharge of the laser medium, and the transmittance may be reduced due to the adhesion of such contaminants. , May be attached to a window holder having a detachable structure for cleaning. Further, the performance degradation of the laser window is suppressed by supplying a clean gas to the inner surface of the laser window.

[0004]

However, in the conventional apparatus, the gas flow in the vicinity of the inner surface of the laser window is not sufficiently considered, so that the laser medium containing a large amount of contaminants and the like inside the window holder holding the laser window. Remains in some cases, and it may not be possible to effectively suppress the contamination of the inner surface of the laser window.

Accordingly, an object of the present invention is to prevent a contaminated laser medium from remaining on the inner surface of a laser window and to prevent the performance of the laser window from being degraded due to such contaminants.

[0006]

In order to solve the above-mentioned problems, a laser device according to the present invention is provided with a vessel containing a gaseous laser medium, a laser beam provided on a wall of the vessel, and a laser beam inside and outside the vessel. A cylindrical window holder for holding a laser window for transmitting light at an end thereof, a first port provided on a side of the window holder for supplying a clean gas to an inner surface of the laser window, and a side of the window holder. A second port that is provided at a position facing the first port of the unit and exhausts the gas in the window holder.

In this laser device, the second port is provided at a position facing the first port on the side of the window holder and exhausts the gas in the window holder, so that the second port extends along the inner surface of the laser window. 1 port to 2nd
A smooth flow of the cleaning gas toward the port is formed. Therefore, it is possible to prevent the laser medium containing the contaminant from staying near the inner surface of the laser window,
The continuous operation time of the laser device can be extended by increasing the cleaning interval of the laser window, and the life of the laser device can be extended.

The shape of the window holder does not need to be strictly cylindrical (for example, cylindrical), but includes various shapes in which a depression is formed when viewed from inside the vessel. And usually, it is set as the structure which can fix a laser window detachably in the depth of a recess. The first port and the second port may have, for example, a slit parallel to the inner surface of the laser window, or may have a plurality of nozzles arranged in parallel to the inner surface of the laser window. Also, the first port and the second port are not limited to a pair,
A plurality of gas curtains can be formed by a plurality of sets of the first port and the second port to increase the cleanliness near the inner surface of the laser window. Further, the gas supplied to the first port is sufficient if it constitutes the gas contained in the vessel, and does not need to be the laser medium itself. For example, if it does not affect the stability of the oscillation state of the laser, an inert gas or the like irrelevant to the excited substance can be supplied to the first port.

In a preferred aspect, the window holder is provided on the side of the window holder so as to interpose a first port between the window holder and the laser window, and supplies a purified gas into the window holder. Is further provided.

[0010] In this case, the third port is provided so as to interpose the first port between the third port and the laser window, and supplies the purified gas into the window holder.
A part of the cleaned gas from the port flows into the vessel and forms a kind of seal, which can prevent the laser medium inside the vessel from being pushed into the vicinity of the inner surface of the laser window. Therefore, the periphery of the laser window can be kept cleaner.

In a preferred aspect, the second port is
Communicate inside the vessel. In this case, there is no need to apply a special negative pressure to the second port for exhausting from the second port, and the structure of the air supply / exhaust mechanism can be simplified. When the second port is not communicated with the inside of the vessel, it is necessary to devise a method of circulating the gas discharged from the second port to the vessel or purifying the gas and sending it to the first port again.

[0012]

FIG. 1 is a diagram for explaining the outline of the overall structure of an embodiment of a laser device according to the present invention.

This laser device is a gas laser, and has a vessel 2 which is a cylindrical container for accommodating a gaseous laser medium, and a pair of vessel flanges 2a and 2b formed opposite to both ends of the vessel 2, respectively. It has a pair of window holders 3 attached thereto and a pair of mirror holders 5 fixed to the ends of both window holders 3.

The vessel 2 is a pressure vessel, in which a laser medium gas such as an excimer is stored. The laser medium gas is pumped by an excitation device (not shown) housed in the vessel 2 together with the laser medium gas. When excimer is used as the laser medium gas, contaminants generally accumulate in the laser medium gas containing excimer due to a reaction between the excimer and the vessel 2 or discharge. Such contaminants destabilize the operation of the laser device and degrade its performance, so that it is necessary to constantly purify the laser medium gas.

Each window holder 3 holds a laser window 4 at an end. The interior of each window holder 3 is hollow, and communicates with the interior of the vessel 2. That is, the internal space of the window holder 3 is filled with the laser medium gas.

Each mirror holder 5 includes a window holder 3
, And each has a built-in resonator mirror 6 arranged to face the laser window 4. The two resonator mirrors 6 constitute a laser resonator as a unit.

The vessel 2 communicates with a gas processor 8 having a built-in pump through a pipe 71.
Communicates with the filter 9 through the pipe 72,
Is branched into and communicated with the internal space of both window holders 3 via a pipe 73.

The operation of the laser device shown in FIG. 1 will be described. Light from the excited laser medium gas inside the vessel 2 is extracted to the outside through the laser windows 4, 4 provided in the window holders 3, 3. This light
The light is incident on the two resonator mirrors 6 provided on the two mirror holders 5 fixed thereto, and is reflected on the inner surfaces thereof. At this time, only the light that satisfies the resonance condition by the two resonator mirrors 6 is amplified and laser oscillation occurs. The laser light thus obtained passes through one of the resonator mirrors 6 and is taken out of the illustrated laser device.

At this time, the laser medium gas is purified in order to prevent the laser medium gas in the vessel 2 from being contaminated and performance degradation. Specifically, the laser medium gas in the vessel 2 is sucked into an external gas processor 8 to remove gaseous impurities (contamination). Further, the laser medium gas that has passed through the gas processor 8 is introduced into the filter 9 to remove particulate contaminants (contamination). The purified laser medium gas is branched and introduced into the window holders 3 and 3. Here, as described in detail below, the laser medium gas introduced into each window holder 3 flows along the inner surface of each laser window 4 as a laminar flow. A clean laser medium gas is always supplied near the side surface. Therefore, the probability that the contamination adheres to the inner surface of each laser window 4 can be reduced, and the interval for cleaning the laser window 4 can be lengthened.

FIG. 2 is a view for explaining the detailed structure of the window holder 3 and the like. A gate valve 2 is attached to the vessel flange 2a at the end of the vessel 2 using a seal ring.
1 is airtightly fixed. The window holder 3 is hermetically fixed to the gate valve 21 using a seal ring. The gate valve 21 separates the internal space of the vessel 2 from the internal space of the window holder 3 when exchanging the laser window 4.

At an end of the window holder 3, a laser window 4 for separating a laser medium gas from an external space during operation of the laser device is fixed. The laser window 4 is air-tightly fixed to a jig 31 using a seal ring, and is detachable from the window holder 3. When the jig 31 is fixed to the window holder 3,
The seal ring keeps the internal space (window port) of the window holder 3 airtight.

A pipe 73 extending from the filter 9 is connected to a side portion of the window holder 3. This pipe 73
Communicates with a pair of ports 32a and 32b formed on the side of the window holder 3. Also, window holder 3
A second port 32c is formed at a position on the side of the first port 32a opposite to the first port 32a. The second port 32c is once drawn out of the window holder 3 via a pipe 74, and It is pulled back inside the vessel 2 again through the flange 2a.

The overall flow of the laser medium gas will be described. The clean laser medium gas from the pipe 73 provided in the window holder 3 is branched into a pair of ports 32a and 32b and supplied to the internal space of the window holder 3. The laser medium gas discharged from the first port 32a into the shield chamber SC is moved along the laser window 4 into the second
It flows toward the port 32c and flows into the vessel 2 at a lower pressure. At this time, the first port 32a is connected to the second port 32c.
, The first port 32a
Will flow along the inner surface of each laser window 4 as a laminar flow, and the clean laser medium gas will always be supplied near the inner surface of the laser window 4. Become.

On the other hand, the shield chamber S
The laser medium gas discharged to the vessel 2 side from C is
It goes straight and goes to the opposite surface, but branches off at the lower inner surface of the window holder 3, and one flows into the vessel 2,
The other goes to the second port 32c. As in the former case, the laser medium gas flowing toward the inside of the vessel 2 forms a flow flowing from the window holder 3 to the inside of the vessel 2, and the laser medium gas containing the contaminant inside the vessel 2 flows into the shield chamber S.
It has the role of preventing it from flowing into C. As in the latter case, even if the laser medium gas containing the contaminant inside the vessel 2 slightly flows into the shielded chamber SC, the laser medium gas heading to the second port 32c immediately flows into the second chamber 32c.
It has a role of returning to the vessel 2 via the port 32c.

The laser medium gas inside the vessel 2 is stirred by a stirrer (not shown).
The laser medium gas in the vessel 2 is made uniform.

FIG. 3 shows the first and second ports 32a, 32a.
It is a figure explaining shape and arrangement of c. Each of the first and second ports 32a and 32c has a slit-shaped nozzle. These nozzles are arranged to face each other so as to face the shield chamber SC formed in the window holder 3, and it can be seen that a laminar flow of a clean laser medium gas is formed in the shield chamber SC. . That is, the entire inner surface of the laser window 4 is always in contact with the clean laser medium gas, and the inner surface of the laser window 4 is kept clean.

[0027]

As is apparent from the above description, according to the laser apparatus of the present invention, the second port is provided at a position opposite to the first port on the side of the window holder, and the gas in the window holder is provided. , A smooth flow of the cleaning gas from the first port to the second port is formed along the inner surface of the laser window. Therefore,
Since the laser medium containing contaminants can be prevented from staying in the vicinity of the inner surface of the laser window, the cleaning interval of the laser window can be lengthened and the continuous operation time of the laser device can be increased, and the life of the laser device can be extended. Can be lengthened.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a structure of a laser device according to an embodiment.

FIG. 2 is a diagram illustrating a structure near a window holder.

FIG. 3 is a diagram illustrating the shape and arrangement of first and second ports provided in a window holder.

[Explanation of symbols]

 2 Vessel 3 Window holder 4 Laser window 5 Mirror holder 6 Resonator mirror 8 Gas processor 9 Filter 32a First port 32a, 32c Second port 32b Third port

Claims (3)

[Claims] 1. A vessel for accommodating a gaseous laser medium, and a cylindrical window holder provided on a wall of the vessel and holding at an end a laser window for transmitting laser light into and out of the vessel. A first port provided on a side portion of the window holder and supplying a purified gas to an inner surface of the laser window; and a first port provided on a side portion of the window holder facing the first port. A second port for discharging gas in the window holder. 2. The apparatus according to claim 1, wherein the window holder is provided on the side of the window holder so as to interpose the first port between the window holder and the laser window, and supplies a purified gas into the window holder. The laser device according to claim 1, further comprising three ports. 3. The laser device according to claim 1, wherein the second port communicates with the inside of the vessel.