JPH03124081A - Controlling apparatus for co2 gas laser - Google Patents

Abstract

PURPOSE:To surely ignite a discharge tube by a method wherein, at a start, an output of a changeover circuit, a discharge voltage and an output of a power setting circuit are changed over from a voltage control operation to a power control operation by means of a feedback control operation. CONSTITUTION:In a control apparatus of a CO2 gas laser, a changeover circuit 38 is not operated wholly at a start. When an output of a waveform setting circuit 33 rises, a first delay circuit 36 counts a set time, executes a voltage feedback control operation and surely ignites a discharge tube at the start. When an output of the circuit 36 counts up the set time and rises, changeover switches of the circuit 38, a discharge voltage and a setting circuit 41 are changed over. Then, an output of a power detection circuit 30 is input to an inverted terminal of an error amplification circuit 34, and an output of a power setting circuit 53 of the circuit 41 is input to a non-inverted terminal; a power feedback control operation is executed to prevent an overshoot and a damping at a rise of a waveform.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a control device for an RF-excited C○2 gas laser,
In particular, it relates to voltage feedback control, power feedback control, and laser power feedback control at the time of start and during steady state after start.

Conventional technology Regarding feedback control of conventional RF-excited CO2 gas lasers, the output of a power setting circuit that sets the magnitude of the laser output, the output of a power detection circuit that detects the magnitude of high-frequency output, or the magnitude of the laser power is The output of the laser power detection circuit to be detected is input to an error amplifier circuit, and the output of the error amplifier circuit is input to an attenuator.

The configuration of the RF excitation oscillator is shown in Figure 3 below, and the conventional RF
The configuration of the excited CO2 gas laser device and its II+ control block diagram are shown in FIGS. 4 and 5.

First, Figure 3 shows the configuration of a general high-speed axial flow type RF excitation oscillator, in which metal parallel plate electrodes 3 and 4 are provided in close contact with the outer periphery of a discharge tube 2 made of a dielectric material such as glass. There is. The parallel plate electrodes 3 and 4 receive the output from the high frequency power source 1,
For example, 13.56MHz.

2.5KW, 2-3KV is supplied. A discharge 5 occurs in the discharge space within the discharge tube 2 sandwiched between the parallel plate electrodes 3 and 4 in the direction shown by the arrow. A mirror (total reflection mirror) 6 and an output mirror (partial reflection mirror) 7 fixedly arranged at both ends of the discharge space form an optical resonator, and a laser output 8 is extracted from the output mirror 7. laser gas 9
The laser gas 9 is circulated through the air supply pipe 1°, and the laser gas 9 whose temperature has been raised by a blower 12 that circulates the discharge 5 and the laser gas λ is cooled by a heat exchanger 11.

The high frequency power source 1 in FIG. 3 corresponds to the RF power source 13 in FIG. 4.
The output of the power supply 13 is transmitted via a coaxial cable 14 to a matching box 15 for matching with a load. The output of the matching box 15 is connected to coupling capacitors 16 to 1 provided to balance the parallel load.
8, and discharge tubes 19-21 are connected to coupling capacitors 16-18.

Referring to FIG. 5, the output of the oscillation circuit 23 passes through a switch circuit 24 and is then input to an attenuation circuit 25 that controls the magnitude of the RF output.

The output of the attenuation circuit 25 is input to a preamplifier 26, and the output of the preamplifier 26 is input to a driver 27. The output of the driver 27 is input to an amplifier circuit 28 using a vacuum tube or the like, and the output of the amplifier circuit 28 is input to a tuning circuit (tank circuit) 2.
is entered into. The output of the tuning circuit 29 is the power detection circuit 3
After passing through 0, it is output from the coaxial cable connector 31 to the outside.

Further, the output of the starting circuit 32 is manually input to the waveform setting circuit 33 in pulse mode or CW mode, and the waveform setting circuit 33
A signal in which the pulse frequency and pulse width in the pulse mode are set, or the energization and output period in the CW mode is outputted from. The switch circuit 24 opens and closes in conjunction with the output of the waveform setting circuit 33, and when the switch circuit 24 is open, the RF ratio output is instantaneously cut off and turned off.

The output of the power setting circuit 35 that sets the RF ratio output magnitude, that is, the magnitude of the laser output, is input to the non-inverting terminal of the error amplification circuit 34. On the other hand, the output of the power detection circuit 30 is input to the inverting terminal of the error amplification circuit 34, and the output of the error amplification circuit 34 is input to the attenuation circuit 25. Attenuation circuit 25
The input varies from O to 5V, etc., and the higher the input, the greater the RF output, controlling the RF ratio output.

Problem to be Solved by the Invention The discharge starting voltage of the discharge tube of an RF-excited CO2 gas laser is D.
Although this voltage is low compared to the discharge starting voltage of the discharge tube of a C-excited CO2 gas laser, if the laser power is lowered, the discharge tube may not ignite reliably. In addition, when feedback control is performed using a laser power detection circuit that detects the magnitude of laser power at the rise of the waveform in pulse mode or CW mode, the response delay of the detection signal of the laser power detection circuit is extremely slow at about 25 m5ec. The output of this laser power detection circuit and the output of the power setting circuit are compared and amplified by the error amplifier circuit, so the output of the error amplifier circuit that feeds back causes large overshoot and damping, and the laser output also changes at every rise of the waveform. Large oat shoots cause damping.

Further, during steady state after starting, as mentioned above, if the laser power is low, the discharge tube may misfire.

Similarly, when the power supply voltage etc. fluctuates instantaneously during a steady state after starting, and the laser power detection circuit is used to perform feedback control, the response of the detection signal of the laser power detection circuit is Delay is 25m5ec
is extremely slow, so the peak value of the laser output is significantly
Produces sobble.

The present invention eliminates the conventional drawbacks, ensures reliable ignition of the discharge tube, eliminates overshoot and damping at the rising edge of the waveform, and prevents the discharge tube from misfiring even in a steady state after starting (and instantaneous). This provides feedback control that does not cause fluctuations in the peak value of the laser output due to disturbances.

Means for Solving the Problems In order to solve the above problems, a CO2 gas laser control device of the present invention includes a waveform setting circuit for setting a pulse mode or CW mode waveform, a first delay circuit, and the discharge tube. a voltage detection circuit that detects a discharge voltage; a power detection circuit that detects the magnitude of high-frequency power; a first start switching circuit that switches the outputs of the voltage detection circuit and the power detection circuit at the time of start; It is equipped with a discharge voltage and power setting circuit that sets the discharge voltage of the discharge tube and the magnitude of the laser power, and an error amplification circuit that performs feedback control,
The output of the waveform setting circuit is input to the first delay circuit, the output of the first delay circuit is input to the first start switching circuit and the discharge voltage and power setting circuit, and the voltage The output of the detection circuit and the output of the power detection circuit are input to the first start switching circuit, and the output of the first start switching circuit and the output of the discharge voltage and power setting circuit are input to the error amplification circuit. It is formed by inputting it into the circuit.

Further, the output of the first delay circuit is input to a second start switching circuit, and the output of the power detection circuit and the output of a laser power detection circuit that detects the magnitude of laser power are input to the second start time switching circuit. The output of the second start switching circuit and the output of a power setting circuit for setting the magnitude of laser power are input to the error amplifier circuit.

Further, a third start switching circuit switches outputs of the voltage detection circuit, the power detection circuit, the laser power detection circuit, the voltage detection circuit, the power detection circuit, and the laser power detection circuit. , the first delay circuit TI, the second delay circuit T2, the discharge voltage and power setting circuit, and the error amplification circuit, and the output of the voltage detection circuit and the power detection circuit The output and the output of the laser power detection circuit are input to the third start switching circuit, and the output of the first delay circuit T1 is input to the second delay circuit T2 and the third start switching circuit. and the discharge voltage and power setting circuit, the output of the second delay circuit T2 is input to the third start switching circuit, and the output of the third start switching circuit and the discharge voltage, The output from the power setting circuit is input to the error amplifier circuit.

Further, a discharge voltage state detection control circuit that compares the output of the voltage detection circuit with a reference value and outputs a voltage feedback switching signal, the power detection circuit, the voltage detection circuit, and the A first steady-state switching circuit that switches the output of the power detection circuit and the power detection circuit, the discharge voltage and power setting circuit, and the error amplification circuit, and the output of the discharge voltage state detection control circuit and , inputting the output of the power detection circuit and the output of the voltage detection circuit to the first steady state switching circuit, and inputting the output of the first steady state switching circuit and the discharge voltage.

The output from the power setting circuit is input to the error amplifier circuit.

Further, a power injection state detection control circuit that compares the output of the power detection circuit with a reference value and outputs a power feedback signal, the laser power detection circuit, the power detection circuit, and the A second steady-state switching circuit that switches the output of the laser power detection circuit and the power detection circuit, the power setting circuit, and a first error amplification circuit, and the output of the power injection state detection control circuit and ,
The output of the laser power detection circuit and the output of the power detection circuit are input to the second steady state switching circuit,
The output of the steady-state switching circuit and the output of the power setting circuit are input to the error amplifier circuit.

Further, a discharge state detection control circuit incorporating the discharge voltage state detection control circuit and the power injection state detection control circuit, the laser power detection circuit, and the power detection circuit;
the voltage detection circuit; a third steady state switching circuit that switches between the output of the laser power detection circuit, the output of the power detection circuit, and the output of the voltage detection circuit during steady state after starting; and the discharge voltage; A power setting circuit and the error amplification circuit are provided, and the output of the first self-discharge state detection circuit, the output of the laser power detection circuit, the output of the power detection circuit, and the output of the voltage detection circuit are 3, and the output of the third steady state switching circuit and the output of the discharge voltage and power setting circuit are input to the error amplifier.

Operation In the above means, at the time of starting, the discharge voltage setting circuit of the discharge voltage and power setting circuit sets a discharge voltage that is equal to or higher than the discharge starting voltage of the discharge tube, and the voltage feedback control is performed for a time set by the first delay circuit. After that, the switching circuit was used to switch to power feedback control at the start, so the discharge tube was reliably ignited. The magnitude of the high frequency output during power feedback control, that is, the magnitude of the laser power, is determined by the power setting circuit of the discharge voltage and power setting circuit after a time set by the first delay circuit.

In addition, since power feedback control is performed for the time set by the second delay circuit, and then switched to laser power feedback control by the switching circuit at the start, overshoot and damping at the rising portion of the waveform will not occur. do not.

In addition, during steady state after start, the discharge state detection control circuit
When the voltage is slightly higher than the discharge starting voltage of the discharge tube, the voltage feedback control is used, or when fluctuations occur due to instantaneous disturbances, the control is switched to the power feedback control, and from the laser power feedback control to the steady state switching circuit. This prevents the discharge tube from misfiring (,
Moreover, ripples do not occur in the peak value of the laser output due to disturbances. In this way, the output of the detection circuit that is manually input to the start switching circuit allows ■ Voltage feedback control (hereinafter referred to as VFB) - Power feedback control (hereinafter referred to as PFB) (hereinafter referred to as PFB) (hereinafter referred to as laser PFB), ■ Or VFB → PFB, and then → laser PFB
Feedback control at start can be switched to

In addition, by the output of the detection circuit input to the steady state switching circuit and the start switching circuit, the feedback control during steady state can be switched to ■ PFB-+VFB ■ Laser PFB-+PFB ■ Aluiha laser PFB-+VFB or PFB .

Naturally, the above-mentioned feedback control at start ■～■ and feedback control at steady state ■～■ are combined, that is, ■ After VFB-PFB control at start, during steady state, PFB HVFBI:: ■ PFB at start→ After laser PFB control, during steady state,
Laser PFB (to) PFB ■ At start VFB → PFB → After laser PFB control,
During steady state, feedback control can also be performed in combination with laser PFB→VFB or PFB.

Embodiment FIG. 1 is a control block diagram of the RF-excited C*2 gas laser control device of the present invention, and FIG. 2 is a waveform diagram of the main part of FIG. 1.

Components in FIGS. 1 and 2 that are the same as those in FIG. 5 are given the same numbers.

The main waveform diagrams of FIG. 1 and FIG. 2 will be compared and explained. For explanation, start VFB-PFB-Laser PF
After B control, during steady state, laser PFB→VFB or PF
Case B will be explained.

First, in FIG. 1, when the output of the waveform setting circuit 33 as shown in FIG. 2 (a) rises, the first delay circuit 36 counts a set time. During this time, Figure 2 (b)
Voltage feedback control is performed as shown in 54 and 57 in FIG. 2(d) to ensure ignition of the discharge tube at the time of start. The start switching circuit 38 includes a power detection circuit 30.
, the output of the voltage detection circuit 42 , and the output of the laser power detection circuit 43 are inputted to the selector switch 4 .
4゜45 and the changeover switch 50 of the steady state changeover circuit 40
51 is not operating, the output of the voltage detection circuit 42 is input to the inverting terminal of the error amplification circuit 34.

On the other hand, the discharge voltage and the output from the discharge voltage setting circuit 52 of the power setting circuit 41 are input to the non-inverting terminal of the error amplifier circuit 34. Since the output of the first delay circuit 36 is "L", the output of the AND element 63 of the discharge voltage and power setting circuit 41 is "L", and the changeover switch 64 is not operated. When the output of the first delay circuit 36 in FIG. 1 counts up and rises for the set time as shown in FIG. is input to the selector switch 44 and the AND element 63, and the other terminal of the AND element is input to the inverter element 65.
is "H", the output of the AND element 63 becomes "H", the output of the AND element 63 is input to the changeover switch 64, and the changeover switch 44.degree. 64 is switched.

When the changeover switch 44.64 is switched, the error amplifier circuit 3
The output of the power detection circuit 30 is input to the inverting terminal of 4,
On the other hand, the non-inverting terminal of the error amplification circuit 34 has a discharge voltage, no<
, 9-The output of the power setting circuit 53 of the setting circuit 41 is input, and power feedback control is performed as shown in FIG. 2 (C) 55 and FIG. Prevent dumping from occurring.

Then, the time set in the second delay circuit 37 is counted, and when the time is counted up, the second delay circuit 37
The output of the selector switch 45 and the discharge state detection control circuit 39
The output of the laser power detection circuit 34 is input to the inverting terminal of the error amplification circuit 34.

On the other hand, at this time, the output of the laser power setting circuit 53, which is the same as that during power feedback control, is input to the non-inverting terminal of the error amplifier circuit 34, and as shown in FIG.
Laser power feedback control is performed as shown in 66. The output of the second delay circuit 37 may not be input to the discharge state detection control circuit 39.

After the output of the second delay circuit 37 rises as shown in FIG. 2(C),
Laser power feedback control is performed as shown in 66, and the discharge state detection control circuit 39 will be explained here. In the comparator circuit 0146, the voltage detection circuit 42
The output of the comparator circuit C146 is compared with a reference value that sets a voltage slightly higher than the discharge starting voltage of the discharge tube, and when the discharge voltage becomes lower than the reference value in steady state, the output of the comparator circuit C146 becomes "H" and the control It is input to circuit V48. The output of the control circuit V48 is the changeover switch 50 and the inverter element 6.
5, the changeover switch 50 operates, and the output of the inverter element 65 becomes "L", so the output of the AND element 63 becomes "L".

When the output of the AND element 63 becomes “L”, the selector switch 6
4 is switched to the output side of the discharge voltage setting circuit 52, and the output of the discharge voltage setting circuit 52 is input to the non-inverting terminal of the error amplifying circuit 34, and when the changeover switch 50 is operated, The output of the voltage detection circuit 42 is input, and the laser power feedback control is switched from the laser power feedback control to the voltage feedback control only during the period when the control circuit V48 is "H". The timing of the voltage feedback control at this time is shown at 58 in FIG. 2(d) to prevent the discharge tube from losing arc.

The comparator circuit 0146 and the control circuit V48 constitute a discharge voltage state/state detection control circuit. In addition, the comparator circuit C247 compares the output of the power detection circuit 30 or a value obtained by differentiating the output of the power detection circuit 30 with a reference value for setting a reference power value or a reference ripple value,
During steady state, when the power value is lower than the reference value or the ripple value is higher than the reference value, the output of the comparator circuit C247 becomes "H" and is input to the control circuit P49.

The output of the control circuit P49 is input to the changeover switch 51,
The changeover switch 51 operates, the output of the power detection circuit 30 is input to the inverting terminal of the error amplification circuit 34, and the control circuit P
49 switches from laser power feedback control to power feedback control only during the "H" period. At this time, the output of the laser power setting circuit 53 is input to the non-inverting terminal of the error amplification circuit 34.

In addition, the timing of power feedback control at this time is shown in 60, 61, and 62 of Fig. 2 (e), and there are three instantaneous fluctuations in the power supply voltage, etc. Feedback control is performed and compensation is performed so that the set power is achieved.

In laser power feedback control, the response of the laser power detection circuit is as slow as 25 msec, so it cannot compensate for instantaneous power fluctuations, for example, power fluctuations of 0.1 msec to 10 msec.

The comparator circuit C247 and the control circuit P49 constitute a power injection state detection control circuit. Note that the first delay circuit 36 in FIG. 1 is used for ignition of the discharge tube.

The ignition of the discharge tube can also be ensured by replacing the discharge detection circuit with a discharge detection circuit that detects discharge. Further, the input of the start switching circuit 38 is switched by the first delay circuit 36 so that only the output of the voltage detection circuit 42 and the output of the power detection circuit 30 are input.
The magnitude of the laser output may be controlled only by power feedback control while ensuring the ignition of the discharge tube.

In addition, if the lowest high frequency output and lowest laser power are used to reliably ignite the discharge tube, the input of the start switching circuit 38 is changed to the output of the power detection circuit 30 and the laser power detection circuit 43.
The first delay circuit 36 may be used to switch only the output of , to prevent damping of the waveform rising portion and occurrence of overshoot, and then perform laser power feedback control.

Here, the first delay circuit 36 has a set time (1 to 3 m5ec) of the first delay circuit 36 during voltage feedback control.
, it is about 25m5ec, and the second delay circuit 3
It is the same value as T2 of 7.

Also, regarding the steady state switching circuit 4o, if the magnitude of the laser output is controlled only by power feedback control,
The input of the steady-state switching circuit 4o may be the output of the voltage detection circuit 42.

In addition, if the lowest high frequency output and lowest laser power are used to reliably ignite the discharge tube, the input of the switching circuit 40 during steady state is the output of the power detection circuit 3o, and if there is no instantaneous fluctuation, laser power feedback control is performed. good. The combination of the type of output of the detection circuit that is input to the start switching circuit 38 and the type of output of the detection circuit that is input to the steady state switching circuit 40 has a similar effect as can be seen from the explanation of each of the two types above. ) combinations listed in the last part of ■～■
become.

Further, the voltage detection circuit 42 generally debites the discharge voltage with a capacitor and detects the debited discharge voltage and high frequency output.

Furthermore, the control device of the present invention, which is composed of the delay circuit, the start switching circuit, the steady state switching circuit, the state detection control circuit, the setting circuit, the error amplification circuit, and the detection circuit, needs to perform feedback control. When a certain factor occurs, a detection circuit for that factor can be provided based on the same concept, and applications can be developed.

Effects of the Invention According to the present invention as described above, the ignition of the discharge tube is ensured at the time of start, and the occurrence of overshoot and damping at the rising portion of the waveform can be prevented. In addition, the arc of the discharge tube does not occur even in a steady state after starting, it is possible to compensate for instantaneous fluctuations, and no ripples occur in the peak value of the laser output.

[Brief explanation of the drawing]

Figure 1 is a control block diagram of the RF excitation CO2 gas laser control device of the present invention, Figure 2 is a signal waveform diagram of the main parts of Figure 1, Figure 3 is a perspective view of a general RF excitation oscillator, and Figure 4 is a control block diagram of the RF excitation CO2 gas laser control device of the present invention. A configuration diagram of a conventional RF-excited CO2 gas laser device, and FIG. 5 is a control block diagram thereof. 36...First delay circuit, 37...Second delay circuit, 38...Start switching circuit,
39...discharge state detection control circuit, 40...
... Steady state switching circuit, 41... Discharge voltage, power setting circuit.

Claims (11)

[Claims] (1) A waveform setting circuit that sets a pulse mode or CW mode waveform in a CO_2 gas laser control device that injects high frequency power into a discharge tube and generates laser light from gas excited by the high frequency discharge; a first delay circuit, a voltage detection circuit that detects the discharge tube discharge voltage, a power detection circuit that detects the magnitude of high-frequency power, and a first delay circuit that switches the outputs of the voltage detection circuit and the power detection circuit at the time of start 1, a discharge voltage and power setting circuit for setting the discharge voltage of the discharge tube and the magnitude of the laser power, and an error amplification circuit for feedback control; input to a first delay circuit, input the output of the first delay circuit to the first start switching circuit and the discharge voltage and power setting circuit, and input the output of the voltage detection circuit and the power detection circuit. The output of the circuit is input to the first start switching circuit, the output of the first start switching circuit and the output of the discharge voltage and power setting circuit are input to the error amplifier circuit, and the voltage at the start is input to the error amplifier circuit. A CO_2 gas laser control device characterized by switching from feedback control to power feedback control. (2) The CO_2 gas laser control device according to claim 1, characterized in that a discharge detection circuit for detecting ignition and discharge of the discharge tube is used in place of the first delay circuit. (3) The output of the first delay circuit is input to the second start switching circuit, and the output of the power detection circuit and the output of the laser power detection circuit that detects the magnitude of laser power are input to the second start time switching circuit. The output of the second start switching circuit and the output of the power setting circuit that sets the magnitude of the laser power are input to the error amplifier circuit, and at the start, power feedback control is performed. The CO_2 gas laser control device according to claim 1, characterized in that the control device switches to laser power feedback control. (4) Claim 1 characterized in that the output of the power detection circuit and the output of the laser power detection circuit are configured to have the same value at a high frequency output of a certain set magnitude. Or the CO_2 gas laser control device according to item 3. (5) Third start switching for switching outputs of the voltage detection circuit, the power detection circuit, the laser power detection circuit, the voltage detection circuit, the power detection circuit, and the laser power detection circuit. circuit, the first delay circuit, the second delay circuit, the discharge voltage and power setting circuit, and the error amplification circuit, and the output of the voltage detection circuit and the output of the power detection circuit. and the output of the laser power detection circuit are input to the third start switching circuit, and the output of the first delay circuit is input to the second delay circuit, the third start switching circuit, and the discharge. The output of the second delay circuit is input to the third start switching circuit, and the output of the third start switching circuit and the discharge voltage and power setting circuit are input to the voltage and power setting circuit. The output of
C according to any one of claims 1 to 4, characterized in that power feedback control is switched to laser power feedback control.
O_2 gas laser control device. (6) a discharge voltage state detection control circuit that compares the output of the voltage detection circuit with a reference value and outputs a voltage feedback switching signal; the power detection circuit; and the voltage detection circuit; The output of the discharge voltage state detection control circuit includes a first steady state switching circuit that switches the outputs of the power detection circuit and the power detection circuit, the discharge voltage and power setting circuit, and the error amplification circuit. and inputting the output of the power detection circuit and the output of the voltage detection circuit to the first steady state switching circuit, and inputting the output of the first steady state switching circuit and the discharge voltage and power setting circuit. The output of the discharge voltage state detection control circuit is inputted to the error amplification circuit, and the power feedback control and the voltage feedback control are switched in accordance with the state of the output of the discharge voltage state detection control circuit during steady state. The CO_2 gas laser control device according to any one of items 1 to 5. (7) a power injection state detection control circuit that compares the output of the power detection circuit with a reference value and outputs a power feedback signal; the laser power detection circuit; the power detection circuit; a second steady-state switching circuit that switches outputs of the laser power detection circuit and the power detection circuit, the power setting circuit, and the error amplification circuit, the output of the power injection state detection control circuit; The output of the laser power detection circuit and the output of the power detection circuit are input to the second steady state switching circuit, and the output of the second steady state switching circuit and the output of the power setting circuit are input to the second steady state switching circuit. Claims 1 to 3 are characterized in that the laser power feedback control and the power feedback control are switched according to the state of the output of the steady state power injection state detection control circuit which is input to the error amplification circuit. The CO_2 gas laser control device according to any one of Item 6. (8) a discharge state detection control circuit incorporating the discharge voltage state detection control circuit and the power injection state detection control circuit; the laser power detection circuit; and the power detection circuit;
the voltage detection circuit; a third steady state switching circuit that switches between the output of the laser power detection circuit, the output of the power detection circuit, and the output of the voltage detection circuit during steady state after starting; and the discharge voltage; comprising a power setting circuit and the error amplification circuit, the output of the discharge state detection circuit, the output of the laser power detection circuit, and the output of the power detection circuit;
inputting the output of the voltage detection circuit to the third steady state switching circuit; inputting the output of the third steady state switching circuit and the output of the discharge voltage and power setting circuit to the error amplifier; Claims 1 to 7 are characterized in that during steady state, laser power feedback control, power feedback control, and voltage feedback control are switched according to the state of the output of the discharge state detection control circuit.
CO_2 gas laser control device according to any one of paragraphs. (9) At the start, the voltage feedback control is switched to the power feedback control after the time set by the first delay circuit, and in the subsequent steady state, the power feedback control and the voltage feedback control are switched to the power feedback control by the discharge voltage state detection control circuit. The CO_2 gas laser control device according to any one of claims 1 to 8, characterized in that the control device is configured to switch depending on the state of the output. (10) At the start, power feedback control is switched to laser power feedback control after the time set by the first delay circuit, and then during steady state, laser power feedback control and power feedback control are switched to the power injection state detection control. The CO_2 gas laser control device according to any one of claims 1 to 9, characterized in that the switching is performed according to the state of the output of the circuit. (11) At the start, switch from voltage feedback control to power feedback control after the time set by the first delay circuit, and then from power feedback control to laser power feedback control after the time set by the second delay circuit. After switching, during a steady state thereafter, laser power feedback control, power feedback control, and voltage feedback control are switched according to the state of the output of the discharge state detection control circuit. The CO_2 gas laser control device according to any one of items 1 to 10.