Coherent light generators – Particular active media – Semiconductor
Reexamination Certificate
2000-08-28
2003-05-27
Ip, Paul (Department: 2828)
Coherent light generators
Particular active media
Semiconductor
C372S058000, C372S061000
Reexamination Certificate
active
06570899
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a gas laser device, and articularly relates to a gas laser device including a dust filter or eliminating dust generated in a laser chamber.
BACKGROUND ART
A dust filter for eliminating dust generated inside a laser chamber in a laser device such as an excimer laser device and a fluorine laser device is conventionally known and is disclosed in, for example, Japanese Patent Laid-open No. 6-132582.
FIG. 10
shows a configuration of a section in a side view of an excimer laser device
101
disclosed in Japanese Patent Laid-open No. 6-132582, and
FIG. 11
shows a section taken along the line
11
—
11
in FIG.
10
.
FIG. 11
is illustrated so that the vertical direction is reversed.
In FIG.
10
and
FIG. 11
, an excimer laser device
101
includes a laser chamber
102
containing laser gas being a laser medium. A pair of discharge electrodes
105
and
105
for causing discharge to happen to excite laser gas and oscillating laser light are disposed to face to each other inside the laser chamber
102
. Further, inside the laser chamber
102
, a flow-through fan
121
for circulating the laser gas inside the laser chamber
102
to send it to an area between the discharge electrodes
105
and
105
, and a heat exchanger
103
for cooling the laser gas heated between the discharge electrodes
105
and
105
are respectively placed at predetermined positions.
Window holders
110
and
110
are provided at both front and rear end portions of the laser chamber
102
. A front and rear windows
107
and
109
for transmitting the laser light are respectively fixed at tip end portions of the window holders
110
and
110
. Labyrinths
111
and Ill are placed between the laser chamber
102
, and the windows
107
and
109
.
Inside the laser chamber
102
, the discharge electrodes
105
and
105
arc worn by discharge, and very small metal powder, halogenide thereof and the like are generated. The excimer laser device
101
includes a dust filter
112
for eliminating the dust. A filter case
114
including filter elements
113
and
113
therein is connected to an outer wall
102
B of the laser chamber
102
. The laser chamber
102
and the filter case
114
arc communicated with each other via a filter inlet port
115
provided at approximately a center portion in a longitudinal direction of the discharge electrodes
105
and
105
and a filter outlet port
116
provided at both end portions of the laser chamber
102
.
A flow line of the laser gas which is circulated inside the laser chamber
102
by the flow-through fan
121
driven by a motor
120
is shown by the arrows G in FIG.
10
and FIG.
11
. Part of the laser gas G circulated by the flow-through fan
121
is drawn from the filter inlet port
115
into the filter case
114
, as shown by the arrow G
1
, and separates into a left and right side to pass through the filter elements
113
. Thereby, the dust mixed in the laser gas G
1
is caught by the filter elements
113
and
113
. The laser gas G
1
having the dust eliminated to be clean is discharged to the insides of the window holders
110
and
110
and passes through the labyrinths
111
to return into the laser chamber
102
.
As shown in
FIG. 10
, the filter inlet port
115
is provided at a corner of an inner wall
102
A of the laser chamber
102
, and forms a receiving port like a funnel relative to the laser gas G. Thereby, the laser gas G
1
is passed into the filter case
113
from the filter inlet port
115
as much as possible and thereby the amount of the dust caught is increased.
However, the prior art disclosed in Japanese Patent Laid-open No. 6-132582 has the disadvantages described below.
Specifically, in the prior art, as shown in
FIG. 10
, the filter inlet port
115
forms the receiving port like a funnel. The flow of the laser gas G passing near the filter inlet port
115
and flowing into between the discharge electrodes
105
and
105
is disturbed by the receiving port. In addition, since the filter inlet port
115
is provided only at approximately the center portion in the longitudinal direction of the discharge electrodes
105
and
105
as shown in
FIG. 11
, such disturbance selectively occurs at approximately the center portion in the longitudinal direction of the discharge electrodes
105
and
105
. As a result, at approximately the center portion of the longitudinal direction of the discharge electrodes
105
and
105
, the average flow rate sometimes reduces to be lower than at the other points. Such reduction of the flow rate sometimes occurs as a variation with time, and the phenomenon in which the flow rate suddenly reduces and thereafter returns to the original value sometimes happens.
When there is ununiformity in the flow rate distribution of the laser gas G between the discharge electrodes
105
and
105
in the longitudinal direction of the discharge electrodes
105
and
105
, discharge is disturbed and becomes unstable at the points at which the flow rate is slow, thus causing the disadvantages that the power of the laser light is reduced and no more energy can be inputted. If the flow rate of the laser gas G is varied with time, when the flow rate is low as described above, the power of the laser light is reduced and the variation of the power with time is increased.
SUMMARY OF THE INVENTION
The present invention is made to eliminate the above disadvantages of the prior art, and its object is to provide a gas laser device in which a flow rate of laser gas flowing between discharge electrodes is approximately uniform in a longitudinal direction of the discharge electrodes without a variation with time.
In order to attain the above object, a gas laser device according to the present invention includes
a laser chamber containing laser gas;
a pair of discharge electrodes disposed inside the laser chamber to face to each other for exciting a laser medium by discharge to thereby oscillate laser light,
a fan for circulating the laser gas to send the same to an area between the discharge electrodes, and
a dust filter for eliminating dust generated inside the laser chamber; and has a configuration
in which a filter inlet port, which is formed in an inner wall of the laser chamber and guides the laser gas into the dust filter, is formed to be approximately vertical to a flow line of the laser gas flowing inside the laser chamber.
According to the above configuration, the filter inlet port seldom disturbs the flow of the laser gas flowing inside the laser chamber. Accordingly, the flow rate of the laser gas in the longitudinal direction of the discharge electrodes is seldom lowered at a specific point or seldom varied by being influence by the filter inlet portion. Thereby, it becomes possible to obtain the flow of the laser gas with the flow rate being always fixed and stable, and thus the discharge becomes stable and the output of the laser light also becomes stable.
Further, a gas laser device may include
a laser chamber containing a laser medium,
a pair of discharge electrodes disposed inside the laser chamber to face to each other for exciting the laser medium by discharge to thereby oscillate laser light,
a fan for circulating laser gas to send the same to an area between the discharge electrodes, and
a dust filter for eliminating dust generated inside the laser chamber; and may have the configuration in which
a filter inlet port, which is formed in an inner wall of the laser chamber and guides the laser gas into the dust filter, is formed over approximately an entire area in a longitudinal direction of the discharge electrodes.
According to the above configuration, the filter inlet port has approximately uniform influence on the flow rate distribution of the laser gas over the entire area in the longitudinal direction of the discharge electrodes. Accordingly, the flow rate of the laser gas in the longitudinal direction of the discharge electrodes seldom is reduced at a specific point or varied by the influence of the filter inlet port.
Furthermore, a gas laser device may include
a laser ch
Ishihara Takanobu
Yabu Takayuki
Yoshioka Shunsuke
Armstrong Westerman & Hattori, LLP.
Ip Paul
Jackson Cornelius H
Komatsu Ltd.
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