JPH0818127A - Gas laser apparatus - Google Patents

Abstract

PURPOSE:To provide a gas laser apparatus, which can quickly replace a window provided at the attaching parts of an airthight container readily. CONSTITUTION:In a gas laser apparatus, which excites gas laser medium and generates laser light, the following parts are provided. In an airtight container 12, the gas laser medium is sealed in the inside. Attaching parts are provided at both ends in the axial direction of the airtight container. An opening valve 21 is provided at the attaching part or the end part in the axial direction of the airtight container and can seal the inner space of the airtight container. A holder 23 holds an optical member 14 and is attached to the attaching part in the airtight state so that the holder is freely attached and removed. A feeding and exhausting device 31, which exhausts the air in the space part between the opening valve and the optical member and feeds inactive gas into the space part, is provided. A pressure lead pipe 32 for communication and cutoff of the space part and the inner surface of the tightly closed container is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas laser device which excites a gas laser medium by discharge to generate laser light.

[0002]

2. Description of the Related Art In an excimer laser device using a fluorine-based mixed gas as a gas laser medium, its output is inevitably lowered with the passage of time. One of the causes is contamination of the window member (optical member) provided at both axial ends of the airtight container in which the gas laser medium is sealed.

That is, when laser light (ultraviolet light) generated by discharge-exciting a gas laser medium in an airtight container irradiates the window member, electrons on its surface are photon.
Released by pressure. When a substance having a high electronegativity such as fluorine (F ₂ ) is present in the gas laser medium, the fluorine takes in the electrons emitted from the window member and becomes F ⁻ while the laser light of the window member is emitted. The irradiated part is positively charged.

On the other hand, when the gas laser medium is excited by electric discharge, the laser medium and various impurities become plasma in the airtight container. Among them, the negatively charged impurities adhere to the positively charged window member and become dirt. Therefore, the laser light is absorbed and scattered by the window member, and the output is reduced.

Therefore, conventionally, a holder holding the window member is detachably attached to a mounting portion provided at both axial ends of the airtight container by a plurality of screws, and if the window member is dirty, the screw is attached. Was loosened, the holder was removed, and the window member was replaced.

However, the work of loosening a plurality of screws to remove the holder and then replacing the window member may not be able to be carried out quickly, and the gas laser device may be used for exposure. When installing in a clean room for use as a light source, it may not be possible to secure a sufficient installation space. In such a case, it may be difficult to replace the window member.

Further, in an excimer laser device using a fluorine-based mixed gas as a gas laser medium, since the gas laser medium is toxic, if the window member is removed and the airtight container is opened, the gas laser is opened. -There was a case where the medium leaks to the outside, which is an undesirable situation.

Therefore, in order to solve such a problem, a gas laser device as shown in FIG. 4 has been considered. That is, in the figure, reference numeral 1 designates an airtight container having a gas laser medium filled therein. Inside the airtight container 1, a pair of main electrodes 2 for exciting discharge of the gas laser medium.
Are spaced apart in parallel.

Mounting portions 3 are formed at both axial ends (only one is shown) of the airtight container 1. The mounting portion 3 is provided with a sluice valve 4 as an opening / closing means for sealing the airtight container 1 in the middle thereof, and a holder 6 holding a window member 5 is detachably attached to the tip end thereof in an airtight state. There is. As a means for attaching the holder 6 to the mounting portion 3 in an airtight and detachable manner, a method in which electromagnets are provided at both ends of these holders for magnetic coupling, a bayonet method, or the like is considered.

The airtight container 1 has a first supply / exhaust pipe 7 for supplying / exhausting a gas laser medium therein.
And a second supply / exhaust pipe 8 for exhausting gas in the space S between the sluice valve 4 and the window member 5 and supplying inert gas to the space S is connected to the mounting portion 3. Has been done.

In such a structure, the window member 5
When it is dirty and needs to be replaced, the gate valve 4 is first closed to seal the space S. Then, if the holder 6 is removed from the mounting portion 3 and the window member 5 is replaced with a new one,
The holder 6 is attached to the attachment portion 3.

Since the atmosphere has entered the space S, it is exhausted by the second supply / exhaust pipe 8. In the exhausted state, since the space S has a lower pressure than the internal space of the airtight container 1, the gate valve 4 cannot be opened. Therefore, the space S is filled with an inert gas through the second supply / exhaust pipe 8 to increase the pressure. After the filling, by opening the sluice valve 4, the state before the replacement can be restored.

By the way, in such a structure, there are the following problems. That is, it is very difficult to equalize the pressure between the space S and the inside of the airtight container 1 in the state where the gate valve 4 is closed and the space S is filled with the inert gas. Therefore, there is a difference in pressure applied between one side and the other side of the sluice valve 4, so that the sluice valve 4 cannot be opened smoothly.

Particularly, in the case of the sluice valve 4, since the gate is slidably driven to open and close, the opening and closing may be impossible even with a slight pressure difference. Moreover, in order to maintain the airtight state of the gate, an O-ring is used as a sealing member in the sliding portion. Therefore, the sluice valve 4
A pressure difference between one side and the other side may cause an excessive frictional force to the O-ring, which may damage the O-ring.

[0015]

As described above, when the holder is provided with the optical member so that the optical member can be replaced, pressure is applied to one side and the other side of the sluice valve that hermetically closes the internal space of the airtight container during the replacement. A difference may occur, the opening and closing of the sluice valve may not be performed smoothly, and a sealing member provided in a sliding portion of the sluice valve may be damaged.

The present invention has been made in view of the above circumstances, and an object thereof is to open and close means for sealing the inside of an airtight container at the time of replacement when an optical member is held in a holder to facilitate the replacement work. Another object of the present invention is to provide a gas laser device in which a pressure difference does not occur between one side and the other side.

[0017]

In order to solve the above problems, the present invention is a gas laser device for exciting a gas laser medium to generate laser light, in which the gas laser medium is enclosed. An airtight container, mounting portions provided at both axial ends of the airtight container, opening / closing means for sealing the inner space of the airtight container provided at the mounting portion or at an axial end portion of the airtight container, and an optical device. A holder that holds a member and is detachably and airtightly attached to the attachment portion, and a supply / exhaust means that exhausts a space portion between the opening / closing means and the optical member and supplies an inert gas to the space portion. And a pressure guiding means for communicating and blocking the space and the internal space of the closed container.

[0018]

According to the above construction, after exchanging the optical member,
If the space between the opening / closing means and the optical member is exhausted through the supply / exhaust pipe and then filled with an inert gas, the space is communicated with the inside of the airtight container by the pressure guiding means, The same pressure is applied to one side and the other side of the opening / closing means.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show an embodiment of the present invention.
The gas laser device shown in FIG. The apparatus body 11 is provided with an airtight container 12 in which a gas laser medium is enclosed. Mounting portions 13 are provided on both axial ends of the airtight container 12, respectively.
As shown in FIG. 1, the window member 1 as an optical member
4 is provided as described below. A high reflection mirror 15a is arranged to face one of the window members 14, and an output mirror 15b which forms an optical resonator with the high reflection mirror 15a is arranged to face the other window member 14. Has been done.

Inside the airtight container 12, a pair of main electrodes 16 are arranged so as to face each other along the axis thereof. A high voltage is applied to these main electrodes 16 from a high voltage power supply 17.
Thereby, a main discharge is ignited between the pair of main electrodes 16, and the gas laser medium is excited by the discharge. Laser light L is generated by exciting the gas laser medium,
The laser light L is a high reflection mirror 15a and an output mirror 15
The output mirror 15 is amplified by repeating reflection with b.
It is oscillated and output from b.

The device body 11 is provided with a first supply / exhaust device 18 and a control device 19. The first supply / exhaust device 18 forms the gas laser medium by being mixed at a predetermined ratio, for example, Ne, Kr, and F ₂ gas, respectively. It is designed to be supplied to the inside of the airtight container 12 through 20 and discharged from the inside. The controller 19 controls power supply to the electrode 16 and controls supply and discharge of each gas by the first supply / exhaust device 18.

The mounting portion 13 is formed in a tubular shape,
A first opening / closing valve 21 which is a sluice valve, which is opening / closing means, is provided in the middle thereof. On one side surface of the first on-off valve 21, a gate (not shown) that constitutes the on-off valve 21 is provided.
An O-ring 21a for sliding the airtight seal is provided.

An attaching / detaching mechanism 22 is provided at the tip of the attaching portion 13, and the holder 23 is attached to the attaching portion 13 airtightly and detachably by the attaching / detaching mechanism 22. The window member 14 that transmits the laser light L as an optical member is hermetically held in the holder 23 via an O-ring 25.

As the attachment / detachment mechanism 22, an electromagnet is provided on one side of the mounting portion 13 and the holder 23, and a permanent magnet is provided on the other side, and the holder 23 can be attached / detached by controlling the energization of the electromagnet or the bayonet method. A structure that can be attached and detached with one touch is adopted.

The mounting portion 13 is provided with the first opening / closing valve 2
A second supply / exhaust pipe 28, one end of which communicates with the space 26 between the windshield member 1 and the window member 14, is connected. A second opening / closing valve 29 is provided in the middle of the second supply / exhaust pipe 28, and the other end is connected to a second supply / exhaust device 31. The second supply / exhaust device 31 can exhaust the space 26 and supply an inert gas to the space.

That is, the first supply / exhaust device 18 and the second supply / exhaust device 31 are operated by the control device 19 in the exhaust mode or the supply mode.

As the inert gas filled in the airtight container 12, there are argon, nitrogen, neon, etc., but in the case where an inert gas is used as the gas constituting the gas laser medium, for example as a buffer gas. Alternatively, the gas may be supplied from the first supply / exhaust device 18.

One end of a pressure guiding pipe 32 is connected to a portion of the second supply / exhaust pipe 28 which is closer to one end than the second opening / closing valve 29. A third opening / closing valve 33 is provided in the middle of the pressure guiding pipe 32, and the other end is connected to the airtight container 12. Therefore, by opening the third opening / closing valve 33, the space 26 and the inside of the airtight container 12 can be communicated with each other.

Next, the operation of the gas laser device having the above construction will be described. During normal use for generating the laser light L, the high-voltage power supply 17 is operated with the first opening / closing valve 21 opened and the second and third opening / closing valves 29, 33 closed.
A high voltage is applied to the pair of main electrodes 16.

As a result, a discharge is ignited between the pair of main electrodes 16, so that the gas laser medium in the airtight container 12 is excited by the discharge to generate laser light L.
The laser light L passes through the window members 14 and is repeatedly reflected and amplified by the high-reflection mirrors 15a and the output mirrors 15b arranged facing the respective window members 14, and is amplified from the output mirrors 15b. It will be oscillated and output.

When such oscillation of the laser light L is repeated, the window member 14 becomes dirty and the output decreases. In such a case, first, the first opening / closing valve 21 is closed to close the internal space of the airtight container 12. As a result, the space 26 between the first on-off valve 21 and the window member 14 is airtightly separated from the internal space of the airtight container 12. After that, the second supply / exhaust device 31 is set to the exhaust mode, and the space 26
The inside is evacuated and an inert gas is supplied.

Next, the holder 23 is attached by the attachment / detachment mechanism 22.
Is removed from the mounting portion 13 and the window member 14 held by the holder 23 is cleaned or replaced, the holder 23 is mounted on the mounting portion 13 by the detaching mechanism 22.

When the mounting of the holder 23 is completed,
The second supply / exhaust pipe 2 is opened by opening the second on-off valve 29 and operating the second supply / exhaust device 31 in the exhaust mode.
The atmosphere is discharged from the space 26 to which 8 is connected. When the discharge of the atmosphere is completed, the second supply / exhaust device 31 is operated in the supply mode to supply the inert gas to the space 26.

When the supply of the inert gas is completed, the second
The on-off valve 29 is closed, and the third on-off valve 33 provided on the pressure guiding pipe 32 is opened. As a result, the space 26 communicates with the internal space of the airtight container 12, so that the pressure between the space 26 and the interior of the airtight container 12 regardless of the pressure of the inert gas supplied to the space 26. Can be the same. That is, the pressure on the one end side and the other end side of the first on-off valve 21 can be made the same.

In this way, if the pressures on both sides of the first on-off valve 21 become the same, this first on-off valve 21 can be opened smoothly. That is, when the first opening / closing valve 21 is a sluice valve, the pressures applied to both side surfaces of the slidably provided gate are the same, so that the gate is biased to one of the two sides. It is possible to prevent the dynamic resistance from increasing and preventing the smooth opening and closing.

Moreover, it is possible to prevent an excessive sliding resistance from being applied to the O-ring 21a provided for maintaining the airtight state of the gate.
It also does not cause early damage.

FIG. 3 shows another embodiment of the present invention. This embodiment differs from the above-described embodiment in the connection structure of the pressure guiding tube 32. That is, one end of the pressure guiding tube 32 is attached to the mounting portion 13.
And the other end is connected to the airtight container 12.

Even with such a structure, the space portion 26 and the airtight container 12 can be communicated with each other, as in the above-described embodiment. In the embodiment shown in FIG. 3, the same parts as those of the embodiment shown in FIG.

The present invention is not limited to the above embodiment, but can be variously modified. For example, the optical member held by the holder is not limited to the window member, and when the gas laser device is an internal mirror type, the holder holds a reflection mirror forming an optical resonator as the optical member. Good.
Further, the gas laser device is not limited to the excimer laser, but may be a device using another gas laser medium such as CO ₂ gas.

[0040]

As described above, according to the present invention, after removing the holder from the mounting portion and exchanging the optical member, the air is exhausted from the space between the opening / closing means and the optical member by the supply / exhaust means. Then, if an inert gas is supplied to the space portion, the space portion and the airtight container are made to communicate with each other by the pressure guiding means so that the pressure on one side and the other side of the opening / closing means can be made the same. did.

Therefore, not only the opening / closing operation of the opening / closing means can be smoothly performed, but also a biased pressure is applied to the opening / closing means to cause an excessive sliding resistance to the sealing member provided for opening / closing the opening / closing means in an airtight state. There is no need to add any damage.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of a mounting portion of an airtight container according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing the entire gas laser apparatus.

FIG. 3 is an enlarged sectional view of a mounting portion of an airtight container showing another embodiment of the present invention.

FIG. 4 is an enlarged cross-sectional view of a mounting portion of a conventional airtight container.

[Explanation of symbols]

Reference numeral 12 ... Airtight container, 13 ... Mounting portion, 21 ... First on-off valve (opening / closing means), 23 ... Holder, 24 ... Window member (optical member), 26 ... Space portion, 28 ... Supply / exhaust pipe (supply / exhaust means) , 29 ... Second on-off valve (supply / exhaust means), 31 ...
Supply / exhaust device (supply / exhaust means), 32 ... Pressure guide pipe (equal pressure means), 33 ... Third on-off valve (equal pressure means).

Claims (4)

[Claims] 1. A gas laser device for exciting a gas laser medium to generate laser light, wherein an airtight container in which the gas laser medium is sealed, and axially opposite ends of the airtight container are provided. A mounting part, an opening / closing means which is provided at this mounting part or an axial end of the airtight container and can seal the internal space of the airtight container, and an optical member which is detachably and airtightly mounted on the mounting part. A holder, a supply / exhaust means for exhausting the space between the opening / closing means and the optical member and supplying an inert gas to the space, and connecting the space with the internal space of the closed container. And a pressure guiding means for shutting off the gas laser apparatus. 2. The pressure guiding means, one end of which communicates with a space between the on-off valve and the optical member, and the other end of which communicates with the airtight container, and which is provided in the middle of the pressure guiding tube. 2. The gas laser device according to claim 1, wherein the gas laser device comprises an open / close valve. 3. The gas laser device according to claim 1, wherein the optical member is a window member that transmits laser light generated in the closed container. 4. The optical member is a reflection mirror that forms an optical resonator for amplifying laser light generated in the closed container.
The gas laser device described.