Coherent light generators – Particular pumping means – Electrical
Reexamination Certificate
2000-08-28
2003-08-19
Ip, Paul (Department: 2828)
Coherent light generators
Particular pumping means
Electrical
C372S057000
Reexamination Certificate
active
06608853
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a laser apparatus, and more particular to a discharge electrodes structure in a laser apparatus and a laser apparatus provided with the discharge electrodes.
BACKGROUND OF THE INVENTION
Conventionally, there has been known a laser apparatus which excites a laser medium in accordance with a discharge so as to oscillate a laser beam, and the laser apparatus is, for example, described in U.S. Pat. No. 4,959,840.
FIG. 24
shows a cross section near discharge electrodes of an excimer laser apparatus disclosed in the publication, and a description will be given of a conventional art on the basis of FIG.
24
.
In
FIG. 24
, an excimer laser apparatus
101
is provided with a laser chamber
102
for sealing a laser medium such as a laser gas or the like. the laser chamber
1
-
2
can be freely divided into an upper chamber
102
A and a lower chamber
102
B. A pair of discharge electrodes
105
A and
105
B constituted by an anode
105
A and a cathode
105
B for generating a discharge so as to excite a laser gas and oscillate a laser beam are arranged in an inner portion of the laser chamber
102
in an opposing manner.
The anode
105
A is fixed to an anode base
106
made of a conductive body by a bolt
160
, and the anode base
106
is gripped between the upper chamber
102
A and the lower chamber
102
B. Accordingly, the anode
105
A is in the same electric potential as that of the laser chamber
102
(is grounded).
Further, the cathode
105
B is fixed to a cathode supporting member
108
made of an insulative body by a high voltage current supply rod
112
, and is electrically insulated from the laser chamber
102
by insulative members
109
and
110
made of an insulative body such as a ceramic or the like. A high voltage current for being discharged to the cathode
105
B is supplied by the high voltage current supply rod
112
.
However, the conventional art disclosed in U.S. Pat. No. 4,959,840 has the following problems.
That is, during the discharge operation, the opposing portions of the discharge electrodes
105
A and
105
B are gradually abraded and consumed. Accordingly, an interval between the discharge electrodes
105
A and
105
B is increased, and a shape of the discharge electrodes
105
A and
105
B is changed. Therefore, since the discharge operation becomes unstable so as to prevent a power of the laser beam from changing, it is necessary to regularly replace the discharge electrodes
105
A and
105
B. In particular, since the anode
105
A is greatly consumed in comparison with the cathode
105
B, it is necessary to frequently replace the anode
105
A.
However, in accordance with the conventional art, the cathode
105
B is fixed to the upper chamber
102
A and the anode
105
A is gripped between the upper chamber
102
A and the lower chamber
102
B. Accordingly, in order to replace the discharge electrodes
105
A and
105
B, it is necessary to separate the upper chamber
102
A from the lower chamber
102
B, replace the discharge electrodes
105
A and
105
B, thereafter again assemble the upper chamber
102
A and the lower chamber
102
B, so that a lot of labor and time are required. Further, at this time, in order to stabilize the discharge operation, it is necessary to accurately adjust a distance between the anode
105
A and the cathode
105
B in a state of assembling the anode
105
A and the cathode
105
B in the laser chamber
102
, and this adjustment required a lot of labor and time.
Further, by separating the upper chamber
102
A and the lower chamber
102
B, an inner wall of the laser chamber
102
and parts such as a blower (not shown) or the like arranged in an inner portion of the laser chamber
102
are exposed to an air. As a result, a moisture content and an impurity contained in the air are attached to the inner wall of the laser chamber
102
, the blower or the like so as to soil the laser gas, so that a power of the laser beam is reduced. In order to prevent the power from being reduced, there is required a passivation corresponding to an operation of removing the attached moisture content and impurity. Accordingly, it is necessary to stop the excimer laser apparatus
1
for a long time at every replacement of the discharge electrodes
105
A and
105
B, so that the machine availability is reduced.
SUMMARY OF THE INVENTION
The present invention is made by solving the problems in the conventional art mentioned above, and an object of the present invention is to provide a discharge electrodes structure which can be easily replaced and adjustable a distance between the discharge electrodes, and a laser apparatus employing the discharge electrodes.
In order to achieve the object mentioned above, in accordance with the present invention, there is provided a laser apparatus provided with a discharge electrodes structure comprising:
a pair of anode and cathode provided within a laser chamber for sealing a laser medium in an opposing manner, generating a discharge so as to excite the laser medium and oscillating a laser beam;
a conductive anode base holding the anode;
an insulative cathode base placed so as to close an opening portion provided in the laser chamber and holding the cathode; and
a return plate suspending the anode base from the cathode base so as to supply a current to the anode.
In accordance with the structure mentioned above, since the anode is suspended from the cathode by the return plate, it is possible to integrally attach and detach the anode and the cathode to and from the laser chamber at a time of replacing any one of the anode and the cathode. Accordingly, when the structure is made, for example, such that the anode and the cathode are assembled in an external portion of the laser chamber so as to unite and the unit is replaced, it is possible to save labor and time for assembly in comparison with the case of independently assembling the anode and the cathode within the laser chamber.
Further, the laser apparatus provided with the discharge electrodes structure may further comprise an anode support bar for connecting the cathode base to the anode base so as to suspend the anode from the cathode base.
In accordance with the structure mentioned above, since the anode is suspended by not only the return plate but also the anode support bar, it is possible to weaken a strength of the return plate so as to make a thickness and a width of the return plate thin. Accordingly, the return plate does not disturb a flow of the laser medium flowing between the anode and the cathode, so that a flow speed becomes fast and the discharge operation is stably performed.
In addition, for example, when the structure is made such that the anode support bar is provided with a mechanism for positioning the anode and the cathode with respect to each other, it is easy to assemble the anode and the cathode.
Further, the laser apparatus provided with the discharge electrodes structure may be structured such that the anode base is freely separated into an upper anode base for holding the anode and a lower anode base connected to the return plate.
In accordance with the structure mentioned above, since the anode and the lower anode base connected to the return plate are separated, it is unnecessary to take out the return plate at a time of taking out the anode from the laser chamber. Accordingly, it is possible to save labor and time for replacing a battery.
Further, there is provided a laser apparatus provided with a discharge electrodes structure comprising:
a pair of anode and cathode provided within a laser chamber for sealing a laser medium in an opposing manner, generating a discharge so as to excite the laser medium and oscillating a laser beam;
a conductive anode base placed so as to close an opening portion provided in the laser chamber and holding the anode;
an insulative cathode base holding the cathode; and
a return plate connecting the anode base to the cathode base and suspending the cathode base from the anode base so as to supply a current to the anode.
In accordance with the structure mentio
Suzuki Natsushi
Yoshioka Shunsuke
Ip Paul
Komatsu Ltd.
Monbleau Davienne
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