JP3300026B2 - Discharge circuit of high frequency discharge gas laser - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a discharge circuit of a high-frequency discharge gas laser.

[0002]

2. Description of the Related Art Conventionally, in a high-frequency discharge gas laser,
The supply of high-frequency power to the main discharge electrode and the sub-discharge electrodes (pre-discharge electrodes for simmer discharge) is performed by, for example, a circuit as shown in FIG. (The impedance on the load side is selected as the complex conjugate of the impedance on the power supply side.)
It is carried out. That is, the inductor 3 for impedance matching and the capacitor 5 are connected in series to the high-frequency power supply 1, both ends of the capacitor 5 are connected to the main discharge electrode 7, and the sub-discharge electrode 11 is connected via the current limiting capacitor 9. are doing. This circuit is one resonance circuit. When the resonance frequency matches the frequency of the high frequency power supply 1, the power factor becomes 1 and the maximum power can be supplied to the discharge electrode.
However, since the resistance value of the laser gas changes depending on the magnitude of the current, the circuit is matched only at a specific current value.

In this figure, a voltage V applied to a main discharge electrode 7 is
The supply voltage Vcd to ab and the sub-discharge electrode 11 is the same. However, if the distance between the sub-discharge electrodes 11 is smaller than that of the main discharge electrode 7, the discharge start voltage of the sub-discharge electrode 11 decreases, and the sub-discharge electrode 11 can be discharged before the main discharge electrode 7. In this way, the discharge of the main discharge electrode 7 is performed while maintaining the discharge by the simmer discharge of the sub-discharge electrode 11, and the output of the laser is adjusted by increasing or decreasing the voltage of the high frequency power supply 1.

[0004]

As described above, the output of the laser is adjusted by increasing or decreasing the voltage of the high-frequency power supply 1. When the voltage of the high-frequency power supply 1 is increased to increase the laser output, the main discharge electrode 7 is increased. , The discharge power of the sub-discharge electrode 11 also increases. Sub-discharge electrode 1
1 is supplied with power through the current limiting capacitor 9 as described above. However, not only is the sub-discharge electrode 11 required to discharge before the main discharge electrode 7 but also the main discharge electrode 7 In order to give a sufficient preliminary discharge effect when discharging, a certain amount of power is required.
There were limits to reducing the value of.

[0005] As described above, when the discharge power of the main discharge electrode 7 increases, the discharge power of the sub-discharge electrode 11 also increases, so that the sub-discharge electrode 11 is consumed by overheating and the sub-discharge electrode 11 affects the main discharge. By being placed in a place that is easy to give,
There is a problem such as partial power concentration of the discharge of the main discharge electrode 7.

The present invention has been made in view of such a problem. Even when the discharge power of the main discharge electrode becomes large, the discharge power of the sub-discharge electrode is suppressed to a relatively small increase. It is an object of the present invention to provide a discharge circuit of a high-frequency discharge gas laser which can prevent the above-mentioned problems.

[0007]

According to the present invention, there is provided a high-frequency discharge gas laser having a main discharge electrode and a sub-discharge electrode, wherein the main discharge electrode is connected to a high-frequency power supply via a first impedance matching section. The main discharge side circuit is configured by connecting the discharge electrodes, and the second
A sub-discharge-side circuit is configured by connecting the sub-discharge electrodes via the impedance matching unit, so that the discharge start voltage of the sub-discharge electrode is lower than the discharge start voltage of the main discharge electrode, and The values of the first and second impedance matching sections are set so that the Q value of the sub-discharge side circuit at resonance is greater than the Q value of the main discharge side circuit at resonance . It was done.

[0008]

According to the present invention as described above, the sub-discharge can always be started before the main discharge, and even if the discharge power by the main discharge electrode is greatly increased, the sub-discharge electrode The increase in the discharge power can be kept relatively small, thereby preventing problems such as consumption due to overheating of the sub-discharge electrodes and partial power concentration of the discharge of the main discharge electrodes.

[0009]

Next, an embodiment of the present invention will be described with reference to FIG. As shown in the figure, a first impedance matching section M1 in which an inductor 3 and a capacitor 5 are connected in series is connected to the high-frequency power supply 1, and both ends of the capacitor 5 are connected to each other.
It is connected to the main discharge electrode 7. Also, the high frequency power supply 1
A second type in which the inductor 13 and the capacitor 15 are connected in series
Of the capacitor 1
Both ends of 5 are connected to a sub-discharge electrode 11 via a current limiting capacitor 9 (which may be omitted). That is, the main discharge side circuit is formed by connecting the main discharge electrode 7 to the high frequency power supply 1 via the first impedance matching section M1, and the sub discharge electrode 11 is connected to the high frequency power supply 1 via the second impedance matching section M2. To form a sub-discharge side circuit.

The voltage between the main discharge electrodes 7 can be arbitrarily set by selecting the values of the inductor 3 and the capacitor 5 of the first impedance matching section M1. The voltage can be set arbitrarily by selecting the values of the inductor 13 and the capacitor 15 of the second impedance matching section M2. Therefore, the discharge voltage of the sub-discharge electrode 1 is higher than the discharge starting voltage of the main discharge electrode 7.
By selecting the values of the inductor 3 and the capacitor 5 of the first impedance matching unit M1 and the values of the inductor 13 and the capacitor 15 of the second impedance matching unit M2 so that the discharge start voltage of the first impedance becomes low,
The sub-discharge can always be reliably started before the main discharge.

FIG. 2 shows an equivalent circuit of FIG.
That is, in FIG. 2, E represents the voltage of the high-frequency power supply 1 of FIG. 1, r represents the internal resistance of the high-frequency power supply 1 of FIG. 1, and ω represents the frequency of the high-frequency power supply 1 of FIG. Also,
L1 and C1 represent the inductance of the inductor 3 and the capacitance of the capacitor 5 of the first impedance matching unit M1 of FIG. 1, respectively, and L2 and C2 are the inductance of the inductor 13 and the capacitor 15 of the second impedance matching unit M2 of FIG. , And R1 and R2 represent discharge load resistances between the main discharge electrodes 7 and the sub discharge electrodes 11 in FIG. As can be seen from the equivalent circuit of FIG. 2, the Q value at the time of resonance of the main discharge side circuit is, for example, the equation Q10 = (R1C1 /
rR1C1 + L1) (L1 / C1) ^1/2 , and the Q value of the sub-discharge side circuit at the time of resonance is expressed by, for example, the formula Q20
= (R2C2 / rR2C2 + L2) (L2 / C2)
It is represented by ^1/2 .

FIG. 3 shows the relationship between the power supply frequency ω and the Q value applicable to the main discharge side circuit and the sub discharge side circuit, respectively, and the Q value indicates the sharpness of the resonance characteristics of the circuit.
As can be seen from this figure, the power supply frequency ω is
When 0, the circuit satisfies the matching condition. The inductance L1 of the impedance matching unit M1 or M2
Alternatively, when L2 and the capacitance C1 or C2 are fixed values, the load satisfying the matching condition of the circuit (the discharge load between the main discharge electrode 7 and the sub-discharge electrode 11) has only one impedance value. Since the discharge load resistance R1 or R2 of the main discharge electrode 7 or the sub-discharge electrode 11 changes non-linearly according to the discharge power, when the impedance is other than one impedance value that satisfies the matching condition, the power factor deviates from the matching condition and decreases. I do. As can be seen from FIG. 3, when the power supply frequency ω deviates from the resonance frequency ω0 (the state where the matching condition is satisfied), the tendency of the Q value to change (reduction in power factor) is that the Q value at the resonance frequency ω0 is low. compared to (figure Q1), we have much size towards what Q value is high at the resonance frequency .omega.0 (figure Q2).

Therefore, the Q value (Q20) of the sub-discharge side circuit
In addition to selecting the inductance of the inductor 13 and the capacitance of the capacitor 15 of the second impedance matching section M2 , the first impedance is higher than the Q value (Q10) of the main discharge side circuit (Q20> Q10). selecting the capacitance of the inductance and the capacitor 5 of the inductor 3 of the matching portion M1
Therefore, even if the discharge power by the main discharge electrode 7 increases greatly,
An increase in discharge power by the sub-discharge electrode 11 can be suppressed to a relatively small value.

[0014]

As described above, the present invention relates to a high-frequency discharge gas laser having a main discharge electrode and a sub-discharge electrode.
A main discharge side circuit is configured by connecting the main discharge electrode to a high frequency power supply via a first impedance matching section, and the sub-discharge electrode is connected to the high frequency power supply via a second impedance matching section. Constitutes a sub-discharge side circuit, so that the discharge start voltage of the sub-discharge electrode is lower than the discharge start voltage of the main discharge electrode, and the sub-discharge side circuit is smaller than the Q value of the main discharge side circuit at resonance. Discharge side circuit resonance
Since the values of the first and second impedance matching sections are set so that the Q value at the time becomes large, the sub-discharge can always be started earlier than the main discharge, and the main discharge can be always performed. Even if the discharge power by the electrode is greatly increased, the increase in the discharge power by the sub-discharge electrode can be suppressed to a relatively small amount. This has the effect of preventing problems such as concentration from occurring.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an embodiment of a discharge circuit of a high-frequency discharge gas laser according to the present invention.

FIG. 2 is an equivalent circuit of FIG.

FIG. 3 is a diagram showing a relationship between a power supply frequency ω and a Q value (sharpness of resonance characteristics).

FIG. 4 is an explanatory diagram of a discharge circuit of a conventional high-frequency discharge gas laser.

[Explanation of symbols]

 M1 First impedance matching section M2 Second impedance matching section 1 High frequency power supply 3, 13 Inductor 5, 15 Capacitor 7 Main discharge electrode 11 Sub discharge electrode

Claims (1)

(57) [Claims] 1. A high-frequency discharge gas laser having a main discharge electrode and a sub-discharge electrode, wherein a main discharge side circuit is configured by connecting the main discharge electrode to a high-frequency power supply via a first impedance matching unit. Forming a sub-discharge-side circuit by connecting the sub-discharge electrode to a high-frequency power supply via a second impedance matching unit, wherein the discharge start voltage of the sub-discharge electrode is lower than the discharge start voltage of the main discharge electrode. made way, and, Q at resonance of the secondary discharge side circuit than the Q value at resonance of the main discharge side circuit
So that the value becomes larger, the first discharge circuit of the high-frequency discharge gas laser, characterized in that setting the value of the second impedance matching section, respectively.