JPH04137576A - Discharge-pumped gas laser oscillator - Google Patents

Abstract

PURPOSE:To enable to discharge-excited gas laser oscillator to stably maintain a desired laser output for a long period by providing a discharging voltage adjusting means and gas pressure adjusting means to the laser oscillator. CONSTITUTION:This discharge-pumped gas laser oscillator 20 is provided with a discharging voltage adjusting means 1 and a gas pressure adjusting means 2 composed of a gas inlet valve 2a and gas exhaust valve 2b. These adjusting means 1 and 2 are operated through a manual controlling mechanism, etc. Therefore, a desired laser output can be obtained at desired timing even during laser oscillation and, at the same time, a stable laser output can be obtained for a long period by finely adjusting the discharging voltage adjusting means 1 and/or gas pressure adjusting means 2.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a discharge-excited gas laser oscillator, and in particular, a discharge-excited gas laser oscillator suitable for continuously oscillating a desired laser output stably over a long period of time during laser oscillation. Regarding gas laser oscillators.

[Conventional technology]

I will explain this by borrowing the schematic diagram of the excimer laser oscillator shown in Figure 1 of the case. This excimer laser oscillator 20 includes a laser tube 21, a discharge power source (22) connected thereto, a gas cylinder 24 and a gas exhaust valve (25) connected via a gas intake valve (23).
It is roughly composed of. The laser tube 21 contains Ne, Kr.
A mixed gas 26 such as and F is sealed at atmospheric pressure or higher, and further includes a main discharge electrode 27 for exciting this gas 26, a gas circulation blower 28 for forcibly circulating this gas 26, and a gas circulation blower 28 for cooling this gas 26. A heat exchanger 29 is installed inside. In such a discharge-excited gas laser oscillator, the gas pressure in the laser tube remains constant and laser oscillation is performed.

[Problem to be solved by the invention]

In recent years, with the spread of discharge-excited gas lasers, there has been a growing demand to maintain stable laser output over a long period of time to improve operating efficiency. For example, in the case of the excimer laser mentioned above,
Filled gas pressure is generally 1 to 5 kg/ai'', but if we borrow Figure 4 and explain it, the broken line (Gl
~G3) As shown in the example, from the laser output Eχ,
When the gas pressure G (Gl, G2, G3) is constant, the usable voltage range of each charging voltage Vχ is limited, and even if each charging voltage Vχ is too high or too low, the laser output Eχ
Overall, when the gas pressure is low (G1), the charging voltage
There is also a characteristic that the voltage range for appropriate use of χ is low, and conversely, when the gas pressure is high (G3), the voltage range for appropriate use of charging voltage ■χ is high.

These examples are shown in the table below. (
However, according to the conventional discharge-excited gas laser oscillator described above, the gas pressure in the laser tube is kept constant during laser oscillation. In other words, there is no known configuration in which the gas pressure is set constant during gas exchange and then the gas pressure is varied during laser oscillation. Therefore, in order to adjust gas pressure (i.e., laser output adjustment) in response to fluctuations in gas pressure due to gas partial exchange or changes in gas temperature during laser oscillation, or to change the laser output itself, it is necessary to use the discharge-excited gas laser. There is an inconvenience that these adjustments and changes must be made after the oscillator temporarily stops laser oscillation. In other words, during laser oscillation, the laser output cannot be freely obtained, and furthermore, the laser output cannot be obtained stably for a long period of time, which is a disadvantage, and the above-mentioned recent requirements cannot currently be achieved. .

In view of the problems of the prior art described above, the present invention aims to provide a discharge-excited gas laser oscillator that can obtain a desired laser output at any time during laser oscillation, and that can stably obtain the laser output over a long period of time. purpose.

[Means to solve the problem]

To achieve the above object, the discharge-excited gas laser oscillator according to the present invention includes a discharge-excited gas laser oscillator 20 including a discharge voltage variable means 1 and a gas pressure variable means 2, as described with reference to FIG. (Claim 1). Next, as a configuration that uses a microcomputer for overall control, the second
Figure and Figure 4 Igl+? ! +1 song←＋J The allFn vibrator 20 includes a discharge voltage variable means 1, a gas pressure variable means 2, a laser output setting means 3, a laser output detection means 4, a discharge voltage detection means 5, a gas pressure detection means 6, and a microcomma. This microcomma stores in advance an optimal correlation data table Dt between gas pressure Gχ, discharge voltage ■χ, and laser output Eχ, and also sets the laser output setting from the laser output setting means 3 before or during laser oscillation. value Ec, and during laser oscillation, the laser output detection value Ea is input from the laser output detection means 4, the discharge voltage detection value Va is input from the discharge voltage detection means 5, and the discharge voltage is input from the gas pressure detection means 6. Input the detected value Va and select the related data table Dt.
, the laser output E corresponding to the laser output setting value Ec
Extract χ, the discharge voltage ■χ corresponding to this laser output Eχ, and the gas pressure Gχ, compare the laser output Eχ (or Ec) and the laser output detection value Ea, and if there is a difference between them, The discharge voltage detection value Va is the discharge voltage ■χ
A discharge voltage variable signal S is supplied to the discharge voltage variable means 1 so that
v and outputs a gas pressure variable signal Sg to the gas pressure variable means 2 so that the detected discharge voltage value Va becomes the gas pressure Gχ.

[For production]

According to the configuration in which the discharge voltage variable means 1 and the gas pressure variable means 2 are additionally installed in the discharge excited gas laser oscillator 20, the desired laser output can be achieved by controlling each means 1.2 individually or simultaneously. IJ@ can be adjusted freely by variable operation. Next, in claim 2, the configuration of claim 1 further includes a microcomma and a data input means for the microcomma (
A configuration in which a laser output setting means 3, a laser output detection means 4, a discharge voltage detection means 5, a gas pressure detection means 6) are additionally provided, and the microcomputer 7 is further provided with an optimal associated data table Dt and data processing flow. According to the method, a command signal (a variable discharge voltage signal Sv, a variable gas pressure signal Sg) which is a calculation result is outputted to a variable discharge voltage means 1 and a variable gas pressure means 2, which are actuators, and cause them to operate according to the command. According to my comma, related data table D
Although it can be controlled in any way depending on the contents of t and the data processing flow, in the above configuration, the associated data table Dt first uses the best laser output Eχ at a certain gas pressure Gχ and a certain discharge voltage ■χ as a parameter. The laser output Eχ corresponding to the laser output setting value Ec at that time, the discharge voltage Vχ and the gas pressure Gχ corresponding to this laser output Eχ are extracted from this associated data table Dt, and this laser output Ec (or Eχ) and the laser output detection value Ea, and if there is a difference, the discharge voltage variable means l sets the discharge voltage detection value Va to the discharge voltage ■χ.
The gas pressure variable signal Sg is output to the gas pressure variable means 2 so that the detected discharge voltage value Va becomes the gas pressure Gχ. For this reason,
The difference between the laser output setting value Ec and the laser output detection value Ea automatically disappears. Therefore, the laser output setting value Ec is the optimum discharge voltage ■χ and gas pressure Gχ
It comes to be driven by. Since the flow is always activated, the laser output Ec is continuously oscillated at a constant value for a long period of time. Further, the laser output setting value Ec is set and changed by operating the laser output setting means 3, so that the laser oscillation preamble can be freely set and changed during laser oscillation. In this case, similarly to the above, the new laser output setting value Ec continues to oscillate for a long period of time until the next laser output setting value Ec is input.

〔Example〕

Embodiments of the discharge-excited gas laser oscillator according to the present invention will be described below with reference to FIGS. 1 to 4. As shown in FIG. 1, an embodiment of the invention according to claim 1 includes a discharge excited gas laser oscillator 20 including a discharge voltage variable means 1, a gas intake valve 2a and a gas discharge valve 2b whose opening surfaces are variable. It is equipped with a gas pressure variable means 2. These means 1 and 2 are operated by a manual control mechanism or the like. Furthermore, the present invention also includes a configuration that is used in microcomputer control as shown in the following claim 2, for example. Therefore, a second embodiment using a microcomputer will be described with reference to FIGS. 2 to 4. Note that the configuration of the discharge-excited gas laser oscillator 20 itself on the actual flow side of the above claims 1 and 2 below uses an excimer gas laser that has already been explained in the prior art section, and therefore, redundant explanation will be omitted in this section. is omitted. Therefore, the embodiment of claim 2 is as follows:
As shown in FIG. 2, in appearance, a discharge excited gas laser oscillator 20 includes a discharge voltage variable means 1, and a gas pressure variable means 2 consisting of a gas intake valve 2a and a gas discharge valve 2b with variable opening areas. and dial type laser output setting means 3
, a laser output detection sensor 4, and a discharge voltage detection sensor 5
, a gas pressure detection sensor 6, and a microcomma.

The microcomma stores a related data table Dt (Dtl, Dt2) in advance, as shown by the line in FIG. This related data table Dt (Dtl.

D t2) is a peak value of each laser output Eχ at each constant gas pressure GI G2, G3, etc. of the discharge-excited gas laser oscillator 20 and its respective charging voltage ■χ which is continuously expressed ( The straight line D tl shown by the solid line in the figure, and each constant gas pressure G1, G2, G3 . Each charging voltage 77 width (lower limit to upper limit) and each laser output Eχ width (
It is possible to prepare two types of intermittent lines (lower limit to vehicle upper limit) (intermittent lines Dt2 shown by lines Gl, G2, G3, etc. shown above from the dotted line in the figure). Next, the operation will be explained.Before or during laser oscillation, the laser output setting value Ec freely set by the operator using the laser output setting means 3 is input to the microcomma. , the laser output detection value Ea from the laser output detection sensor 4, the discharge voltage detection value Va from the discharge voltage detection sensor 5, and the discharge voltage detection value Va from the gas pressure detection sensor 6 are also input.Next, The microcomma sets the laser output Eχ corresponding to the laser output setting value Ec to the related data table Dt.
(Dtl or Dt2), and compares this laser output Eχ with the laser output detection value Ea, and if there is a difference, outputs a correction command signal. This correction command signal is applied to the discharge voltage variable means 1 so that the discharge voltage detection value Va becomes the discharge voltage Vχ corresponding to the laser output Eχ.
output to the gas pressure variable means 2 (gas intake valve 2a or gas exhaust valve 2b) so that the discharge voltage variable signal Sv output to the discharge voltage variable signal Sv and the discharge voltage detection value Va become the gas pressure Gχ corresponding to the laser output Ex and a variable gas pressure signal Sg. That is, until the laser output setting value Ec and the laser output detection value Ea become equal, in other words, the discharge voltage detection value Va and the discharge voltage ■χ become approximately equal, and the discharge voltage detection value Va and the gas Until the pressure Gχ becomes approximately equal,
These variable signals Sv and Sg continue to be oscillated by the discharge voltage variable means 1 and gas pressure variable means 2, which are these actuators. To explain the process flow, first, the discharge-excited gas laser oscillator oscillates at the laser output setting value Ec initially set by the laser output setting means 3 (step 1).
). At the same time, this laser output setting value Ec is input to the microcomma, and the laser output setting value Ec is inputted to the microcomma, and the laser output setting value Ec is
c=Eχ, the corresponding gas pressure Gχ and discharge voltage ■χ
are extracted (step 2). Furthermore, at the same time, the actual laser output, that is, the laser output detection value Ea, is detected from the laser output detection sensor 4, the discharge voltage detection value Va is detected from the discharge voltage detection sensor 5, and the discharge voltage is detected from the gas pressure detection sensor 6. The detected value Va is detected, and these detected values Ea, Va, and Ga are also input to the microcomma (
Step 3). Next, the detected laser output value Ea and the laser output Eχ (-Ec) are compared to determine whether there is a difference (step 4). If there is a difference, the detected discharge voltage value Va
and discharge voltage detection value Va are discharge voltage ■χ and gas pressure Gχ
There is also a difference between In other words, the discharge voltage variable signal Sv is output to the discharge voltage variable means 1, and the gas pressure variable signal Sg is output to the gas pressure variable means 2 (gas intake valve 2a or gas discharge valve 2b) until the difference disappears. (Step 5). Note that in the present invention, it should be noted that the related data table Dt (Dt
The discharge voltage Vχ and gas pressure Gχ extracted by 1 or Dt2) are only reference values, and the detected laser output values E, a
The main purpose of this process is to eliminate the difference between the laser output Eχ (=E c ) and the laser output Eχ (=E c ). For example, discharge voltage detection value V
Even if a becomes the extracted gas pressure Gχ and the discharge voltage detection value Va also becomes the extracted gas pressure Gχ, there is still a difference between the laser output Eχ (=Ec) and the laser output detection value Ea. If so, the variable discharge voltage signal Sv and the variable gas pressure signal Sg are continuously oscillated. Conversely, even if the discharge voltage detection value Va does not become the extracted gas pressure Gχ, and the discharge voltage detection value Va does not become the extracted gas pressure Gχ
Even if not, if there is no difference between the laser output Eχ (-Ec) and the laser output detection value Ea, the discharge voltage variable signal SV
The oscillation of the variable gas pressure signal Sg stops. Although these are for reference, these discharge voltage variable signal 3V and gas pressure variable signal S
Care must be taken to ensure that each of g does not have a large command value at the same time.

Especially when using the latter related data table Dt2, since this is an intermittent line, there are multiple laser outputs Eχ (Eχ1, Eχ2) extracted for a certain laser output setting value Ec.
) may occur. In this case, the optimal gas pressure Gχ is also (Gχ1, Gχ2...)
will be extracted. In this case, in the configuration according to the present invention, since the gas pressure variable signal Sg is also output, even if the laser output is Ec=Ea, it may actually be driven with the inefficient discharge voltage V and gas pressure G. It will happen. Therefore, in order to avoid such a case, it is necessary to create the intermittent line based on paradalums that are close to each other to some extent, and it is important that these variable signals Sv and Sg be outputted in small amounts. Furthermore, although it is good to output these variable signals Sv, Sg at the same time, it is even better to output them alternately, and even better to output the discharge voltage variable signal Sv first. An example of such a series of processing flows will be explained with reference to the flowchart of FIG. In this flowchart example, the related data table Dt used is the latter intermittent line D
t2 (see Figure 4). Therefore, each gas pressure G
Laser output E for χ (Gχ1, Gχ2...)
χ has a peak value Ep (Epl, E p2-
---> and the lower limit E sin (E m1ni, E
m1n2-). That is, the initial setting pressure (temporarily Gχ
2) during laser oscillation (step ■), laser output Ea is detected (step ■), and the microcomputer 7 detects E a
<Emin2 is compared (step ■). At this time, if E a < Emin2, the discharge voltage variable signal +Sv is output to the discharge voltage variable means 1 and the discharge voltage Va
(step ■), the gas pressure variable signal Sg is output to the gas intake valve 2a of the gas pressure variable means 2, which opens it to increase the gas pressure Ga (step ■), and returns to step ■.
If E a < Emin2, then E a > E@
in2 is compared (step ■) At this time, Ea>E
If not min2, return to step ■, but if Ea>EI
If lin2, the discharge voltage variable signal -Sv is output to the discharge voltage variable means 1 to lower the discharge voltage Va (step ■), and the gas pressure variable signal -3g is output to the gas discharge valve 2b of the gas pressure variable means 2. opened and lowered the gas pressure Ga (
Step ■), return to step ■. As mentioned above, in the latter related data table Dt2, there are a plurality of laser outputs Eχ extracted for the laser output setting value Ec (Eχ
1, Ex2...), in this example, the dotted line Dt2 in FIG. 4 is driven so as to become a solid line Dt3. For reference, in the solid line Dt3 of this example,
Point P0 indicates the fresh gas point, and the pulse energy in this state is 210 mJ shown on the right side of the vertical axis in the figure), while point P0 indicates the state where the gas has deteriorated and reached its output limit (the pulse energy in this state is 200 mJ shown on the left side of the vertical axis in the figure).

The effects of the above embodiments will be described below. According to the embodiment of claim 1, even during laser oscillation, by finely adjusting the discharge voltage variable means 1 and/or the gas pressure variable means 2, A desired laser output can be obtained at a desired time, and the laser output can be stably obtained over a long period of time. Next, according to the embodiment of claim 2, even during laser oscillation, as long as the laser output value is set by the laser output setting means 3, the microcomputer inputs and outputs the necessary data and the actuator Discharge voltage variable means 1 and/or gas pressure variable means 2
Since the laser is operated automatically, the laser output can be stably obtained over a long period of time. Further, by simply changing the laser output value using the laser output setting means 3, this new laser output value can be stably obtained over a long period of time, as described above. That is, a desired laser output can be stably obtained at a desired time.

〔Effect of the invention〕

As explained above, according to the discharge-excited gas laser oscillator of claim 1, a desired laser output can be obtained at any time during laser oscillation by finely adjusting the discharge voltage variable means and/or the gas pressure variable means. Not only can this be achieved, but the laser output can be stably maintained over a long period of time. Next, according to the discharge excited gas laser oscillator of claim 2,
After the laser output is set by the discharge voltage variable means, the microcomputer controls the laser output to maintain it stably for a long period of time. Of course, the laser output during laser oscillation can be freely changed by the laser output setting means, and in this case as well, the laser output can be stably maintained over a long period of time by the microcomputer's control.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a discharge-excited gas laser oscillator according to an embodiment of claim 1, FIG. 2 is a schematic diagram of a discharge-excited gas laser oscillator according to an embodiment of claim 2, and FIG. 3 is a diagram of a discharge-excited gas laser oscillator according to an embodiment of claim 2. FIG. 4 is a graph diagram showing an example of the association data table stored in the microcomputer in the present invention. 1...Discharge voltage variable means 2...Gas pressure variable means 3...Laser output setting means 4...Laser output detection means 5...Discharge voltage detection means 6... Gas pressure detection means 7...Microcomputer 20...Discharge excited gas laser oscillator Gχ...
Gas pressure Vχ...Discharge voltage Eχ...Laser output Dt...Related data table Ec...Laser output setting value Ea...Laser output detection value Va...Discharge voltage detection value Ga...Gas pressure detection value Sv...Discharge voltage variable signal Sg...Gas pressure variable signal

Claims (2)

[Claims] (1) A discharge excited gas laser oscillator 20 characterized by a configuration including a discharge voltage variable means 1 and a gas pressure variable means 2. (2) In the discharge excited gas laser oscillator 20, the discharge voltage variable means 1, the gas pressure variable means 2, the laser output setting means 3, the laser output detection means 4, the discharge voltage detection means 5, and the gas pressure detection means 6 and a microcomputer 7, the microcomputer 7 stores in advance an optimal correlation data table Dt of gas pressure Gχ, discharge voltage Vχ, and laser output Eχ, and also adjusts the laser output setting before or during laser oscillation. The laser output setting value Ec is input from the means 3, and during laser oscillation, the laser output detection value Ea is input from the laser output detection means 4, the discharge voltage detection value Va is input from the discharge voltage detection means 5, and the gas pressure is inputted. The gas pressure detection value Ga is input from the detection means 6, and the laser output Eχ corresponding to the laser output setting value Ec is determined from the related data table Dt.
Extract the discharge voltage Vχ and gas pressure Gχ corresponding to this laser output Eχ, compare the laser output Eχ (or Ec) and the laser output detection value Ea, and if there is a difference,
A discharge voltage variable signal Sv is output to the discharge voltage variable means 1 so that the discharge voltage detection value Va becomes the discharge voltage Vχ, and the gas pressure is adjusted so that the gas pressure detection value Ga becomes the gas pressure Gχ. A discharge-excited gas laser oscillator characterized by a configuration in which a gas pressure variable signal Sg is output to a variable means 2.