JPH0628244B2 - Excitation control device for laser amplifier device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a pump control device for a laser amplifier device in which a plurality of discharge pump pulse lasers are cascaded.

(Prior Art) For example, as a method of increasing the output of a laser used for laser processing, photoreaction process, excited ionization of isotope atoms, etc. A laser amplifier device in which laser devices that receive and operate are connected in multiple stages in series is used.

There is, for example, a metal gas laser used in this type of laser amplifier device, and excitation by pulse discharge is often used to obtain high output. In this case, it is necessary to discharge the laser device in the latter stage in synchronism with the arrival time of the laser light delayed by the propagation time of the laser light between the preceding and following stages from the discharge time of the former laser device. The delay circuit is used for the signal circuit for the.

(Problems to be Solved by the Invention) In the laser amplifier device as described above, a thyratron is often used as a switch of a pulse power supply circuit for discharge excitation of each laser device constituting the laser amplifier device. However, in this thyratron, the delay time from when the trigger signal for starting is given to the grid until the discharge is completed, that is, the ionization time is about 20 to 100 n sec (for example, hydrogen thyratron), but this ionization time is the cathode heater of the thyratron. It depends on external conditions such as voltage, ambient temperature or reservoir voltage of the circuit in which the thyratron is used.
Therefore, the pulse width of the laser light handled by the laser amplifier device is, for example, about 30 n sec, but due to the fluctuation of the ionization time of the thyratron, the discharge time of the laser light that has arrived from the preceding stage and the laser device of the latter stage do not match,
There has been a problem that the laser output to the subsequent stage is reduced and the effect of the laser amplifier device is diminished.

It is an object of the present invention to provide an excitation control device for a laser amplifier device, which can correct the fluctuation value of the ionization time of a thyratron for a discharge pumping circuit and suppress the fluctuation fluctuation of the laser output.

[Structure of Invention]

(Means for Solving the Problems) In the present invention, an optically connected laser oscillator and laser amplifier, a high-voltage pulse power supply for laser excitation provided in each of the laser oscillator and the laser amplifier, and these Variable delay circuits that are respectively placed in front of the trigger circuits of the high-voltage pulse power supplies, oscillators that commonly supply repetitive pulse signals to these variable delay circuits, and excitation current detection means that are provided in each of the high-voltage pulse power supplies, Each of the detection signals of the excitation current detection means and the repeating pulse signal of the oscillator are provided as inputs, and a processor that outputs a control signal to each of the variable delay circuits is provided. The time difference variation between the detection signal of the excitation current detecting means and the repetitive pulse signal of the oscillator is commanded while delay time is commanded. When it is detected, it is equipped with a processing means for changing the variable value to a corrected delay time corrected and for sequentially instructing the corresponding variable delay circuit.

(Operation) The variable delay circuit of the laser amplifier uses the delay time of the variable delay circuit of the laser oscillator to determine the propagation time of the laser light from the laser oscillator to the laser amplifier between the high-voltage pulse power supplies of the laser oscillator and the laser amplifier. If a processor issues a delay time that is long by correcting the difference in delay time until the excitation current is generated after receiving the trigger signal, the laser amplifier is excited in accordance with the laser light arrival time from the laser oscillator, The output efficiency of the laser amplifier is best kept.

Here, even if the high-voltage pulse power supply of the laser amplifier causes a gradual change in the delay time from the reception of the trigger signal to the generation of the excitation current, the processor immediately cancels this change and the modified delay time of the laser amplifier is set to the variable delay. Since the circuit is instructed to change the delay time, the application time of the high-voltage pulse for excitation follows the arrival time of the laser beam, and the output reduction of the laser amplifier can be avoided. When the laser amplifiers are cascaded in multiple stages, and also for the laser oscillators located in the first stage, the same operation as described above occurs in each of them.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

In the figure, a laser amplifier 1a that operates by receiving the laser light output of the laser oscillator 1 at a certain distance (for example, 3 m) from the pulse excitation type laser oscillator 1 configured by a metal gas laser, and a further certain distance. A laser amplifier 1b that operates even when receiving the laser light output of the laser amplifier 1a is installed, and the light output of the laser amplifier 1b is used for a required purpose. Both the laser amplifier 1a and the laser amplifier 1b are metal gas lasers like the laser oscillator 1.

A high-voltage pulse power supply 2 for excitation is connected to the laser oscillator 1, the main part of which is a thyratron 3, a trigger circuit 4 connected to the grid of the thyratron 3, and a current transformer for detecting current, which is also provided in the cathode conductor. It is constituted by the container 5. The laser amplifier 1a and the laser amplifier 1b also have a high-voltage pulse power supply 2a and a high-voltage pulse power supply 2b, respectively.
Are connected. Since the configuration of these main parts is the same as that of the high-voltage pulse power supply 2, the corresponding member reference numerals in the high-voltage pulse power supply 2 are denoted by a or b, and the individual description is omitted.

A clock signal generator 7 is provided as a common trigger signal generation source for the trigger circuits 4, 4a and 4b. This repetition frequency is selected to be about 5 kHz, for example. The output signal of the clock signal generator 7 is connected to the trigger circuits 4, 4a, 4b via the variable delay circuits 6, 6a, 6b, respectively. Each of the variable delay circuits 6 and the like can individually set its delay time by a signal from the outside.

A processor 8 is provided for controlling the delay time of the variable delay circuit 6 and the like. The processor 8 is supplied with the clock signal of the clock signal generator 7 and the detection signals of the current transformers 5, 5a and 5b. , Variable delay circuits 6, 6a, 6b
Are connected so as to output control signals of delay time. The processor 8 stores the delay time set at the beginning of each of the variable delay circuits 6, 6a, 6b (set so that the maximum value of the laser output is obtained at the start of operation), and based on this value Thus, the delay time setting value of the variable delay circuit 6 and the like is commanded. After starting the operation of the laser amplifier device, for example, the current transformer 5 is changed from the clock signal.
When the elapsed time up to the detection signal of fluctuates from the value at the start of operation, the difference is calculated, the delay time command value is corrected by this difference, and the process of sending it to the variable delay circuit 6 can be performed. It has become. The variable delay circuit 6a,
Similar processing can be performed for 6b.

Next, the operation of this will be described.

When the clock signal generator 7 is started, the clock signal passes through the variable delay circuit 6 and is delayed, then becomes a trigger pulse by the trigger circuit 4 and is applied to the grid of the thyratron 3. The thyratron 3 discharges after the ionization time has elapsed, generates high-voltage pulses, and repeatedly excites the laser oscillator 1 with pulses. The pulsed laser light output of the laser oscillator 1 generated by this is the repetitive laser amplifier 1a.
Given to. The pulsed laser light reaching the laser amplifier 1a is delayed from the generation time of the laser oscillator 1 by the propagation time of the distance between the laser oscillator 1 and the laser amplifier 1a. The laser amplifier 1a is pulse-excited so as to coincide with the arrival time of the pulsed laser light that has arrived with this delay.
That is, the clock signal of the clock signal generator 7 is delayed by the variable delay circuit 6a and given to the high voltage pulse power supply 2a. The delay time set in the variable delay circuit 6a is roughly a value obtained by adding the propagation time of the pulsed laser light described above to the delay time set in the variable delay circuit 6. Further details will be described later. Then, the laser amplifier 1a is excited by the high-voltage pulse generated by the high-voltage pulse power supply 2a after undergoing the same progress action as for the laser oscillator 1 described above, and repeatedly gives the generated laser light output to the laser amplifier 1b.

The relationship of the operation of the laser amplifier 1b with respect to the laser amplifier 1a is similar to that of the laser amplifier 1a with respect to the laser oscillator 1 and can be easily inferred from the above description, and therefore the description thereof is omitted.

Although the delay time set in the variable delay circuit 6a has been schematically described above, it will be described in detail. When the ionization times of the thyratron 3 and the thyratron 3a are equal, the delay time set in the variable delay circuit 6a is as described above.
It is a value obtained by adding the propagation time between the laser oscillator 1 and the laser amplifier 1a of the pulsed laser light to the delay time set in the variable delay circuit 6. However, the ionization times of the thyratron 3 and the thyratron 3a generally have individual differences. Therefore, for example, when the ionization time of the thyratron 3a is longer than that of the thyratron 3, the delay time of the variable delay circuit 6a is set shorter by the difference.

The initial setting of the delay time of the variable delay circuit 6 including the correction of the individual difference of the ionization time of the thyratron 3 etc.
For example, at the start of operation of the laser amplifier device, in other words, the external conditions of the laser amplifier device are kept constant, the processor 8 is operated by an external means (not shown) so that the maximum output of the laser amplifier 1b is obtained, and a variable delay is provided. This can be done by adjusting the delay time of the circuit 6a or less.

In this way, each laser amplifier 1a etc. is once excited to coincide with the input of the pulsed laser light from the previous stage, and after the laser amplifier device has started operation, it is external to the thyratron 3a etc. Conditions, that is, even if the ionization time of the thyratron 3a or the like changes due to a change in the voltage applied to the cathode heater, or a change in the ambient temperature, the reservoir voltage, etc.
The processor 8 resets the delay time of the relevant one of the variable delay circuits 6a and the like so as to correct this variation. As a result, the pumping of the laser amplifier 1a or the like always coincides with the input timing of the pulsed laser light from the previous stage and does not deviate significantly, so the laser light output of the laser amplifier 1b can maintain the maximum value at the start of operation. it can.

That is, the fluctuation period of the above-mentioned ionization time is much longer than the repetition frequency of the excitation pulse of the laser amplifier 1a or the like determined by the clock signal generator 7, for example, the cycle of 5 kHz. On the other hand, the processor 8 monitors the generation time of the excitation pulse applied to the laser amplifier 1a at that time based on the detection signal from the current transformer 5a for each clock signal of the clock signal generator 7, If it is fast, the delay time of the variable delay circuit 6a can be reset before the next clock signal. Therefore, the delay time setting of the variable delay circuit 6a can completely track and correct the ionization time fluctuation of the thyratron 3a and the like.

Note that the ionization time fluctuation of the thyratron 3 of the laser oscillator 1 does not affect the laser light output of the laser oscillator 1 itself, but if it fluctuates, the pulsed laser light input from the preceding stage of the subsequent laser amplifier 1a etc. When
Since the variation between the excitation pulses is induced, the variable delay circuit 6 acts in the same manner as the variable delay circuit 6a and the like described above to prevent this.

〔The invention's effect〕

According to the present invention, the fluctuation of the generation time of the excitation pulse of each laser device that constitutes the laser amplifier device is prevented, and it is possible to always match the pulse laser light input time from the preceding stage. The output can be kept constant.

[Brief description of drawings]

 FIG. 1 is a block connection diagram showing an embodiment of the present invention. 1 ... Laser oscillator, 1a, 1b ... Laser amplifier 2, 2a, 2b ... High-voltage pulse power supply 4 ... Trigger circuit, 5, 5a, 5b ... Current transformer 6, 6a, 6b ... Variable delay circuit 7 ...... Clock signal generator 8 …… Processor

Claims (2)

[Claims] 1. A laser oscillator and a laser amplifier which are optically connected to each other, and a high-voltage pulse power supply for laser excitation provided in the laser oscillator and the laser amplifier, respectively.
Variable delay circuits which are respectively placed in front of the trigger circuits of these high-voltage pulse power supplies, oscillators which commonly supply repetitive pulse signals to these variable delay circuits, and excitation current detection means which are provided in each of the high-voltage pulse power supplies. And a processor for inputting each detection signal of these excitation current detecting means and the repetitive pulse signal of the oscillator and outputting a control signal to each of the variable delay circuits, the processor including each of the variable delay circuits. When a time difference variation between the detection signal of the excitation current detection means and the repetitive pulse signal of the oscillator is detected, the delay time is commanded, and the variation value is changed to a corrected delay time corrected to sequentially correspond to the delay time. An excitation control device for a laser amplifier device, comprising processing means for instructing a variable delay circuit. 2. An excitation control device for a laser amplifier device according to claim 1, wherein said excitation current detecting means is a current transformer.