JPH06105821B2 - 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, a photoreaction process, excited ionization of an isotope atom, etc. A laser amplifier device in which laser devices that receive and operate are connected in multiple stages in series is used.

For example, a metal gas laser is used in this type of laser amplifier device, and excitation by pulse discharge is often used to obtain a 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 discharge excitation pulse power supply circuit 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 nsec (for example, hydrogen thyratron), but this ionization time is the cathode heater voltage of the thyratron. , Ambient temperature or external conditions such as the 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 nsec, but due to the fluctuation of the ionization time of this thyratron, the discharge time of the laser light that arrived from the previous stage and the laser device of the latter stage do not match, However, there is a problem that the laser output of the device 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) The present invention relates to a laser oscillator and a laser amplifier that are optically cascaded, a high-voltage pulse power supply for laser excitation that is individually provided in the laser oscillator and the laser amplifier, and these. A variable delay circuit that is placed before the trigger circuit of the high-voltage pulse power supply and has a controllable delay time, and an oscillator that repeatedly supplies a parf signal to each of these variable delay circuits,
Discharge light detecting means for detecting discharge light of each of the laser amplifiers, and a processor for inputting each detection signal of the discharge light detecting means and a repeating pulse signal of the oscillator and outputting a control signal to each of the variable delay circuits. Wherein the processor instructs each of the variable delay circuits to their delay time and corrects a fluctuation value when a time difference fluctuation between the detection signal of the excitation current detection means and the repetitive pulse signal of the oscillator is detected. It has a processing means for changing the corrected delay time and sequentially instructing the corresponding variable delay circuit.

(Function) The variable delay circuit of the laser amplifier uses the delay time of the variable delay circuit of the laser oscillator as a trigger for the propagation time of the laser light from the laser oscillator to the laser amplifier. If the processor pre-commands a delay time that is long by correcting the difference in the delay time until the excitation current is generated after receiving the signal, the laser amplifier is excited in accordance with the arrival time of the laser beam from the laser oscillator, and the laser is excited. The output efficiency of the amplifier is best kept.

Here, if the high voltage pulse power supply of the laser amplifier is
Even if there is a slight fluctuation in the delay time from the reception of the trigger signal to the generation of the excitation current, the processor immediately instructs the variable delay circuit of the laser amplifier to make a correction delay time that offsets this fluctuation and redirects the delay time. Therefore, 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 amplifier is continued in multiple stages and also for the laser oscillator located in the first stage, the same operation as described above occurs for each of them.

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

In the figure, for example, a fixed distance (for example, from a pulse excitation type laser oscillator 1 configured by a metal vapor laser)
3 m), a laser amplifier 1a that operates by receiving the laser light output of the laser oscillator 1 and a laser amplifier 1b that operates by receiving the laser light output of the laser amplifier 1a at a certain distance are respectively installed. The optical output of the laser amplifier 1b is commonly used for required purposes. A metal vapor laser is provided for both the laser amplifier 1a and the laser amplifier 1b, like the laser oscillator 1.

A high-voltage pulse power supply 2 for excitation is connected to the laser oscillator 1, and the main part thereof is composed of a thyratron 3 and a trigger circuit 4 connected to the grid of the thyratron 3.

Further, the laser oscillator 1 has a discharge light detector 5 as discharge light detection means for detecting discharge light generated when an excitation current flows. A high-voltage pulse power supply 2a and a high-voltage pulse power supply 2b are connected to the laser amplifier 1a and the laser amplifier 1b, respectively. Since the configuration of these main parts is the same as that of the high-voltage pulse power supply 2, a member code in the corresponding high-voltage pulse power supply 2 is represented by a or b,
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. The variable delay circuits 6 and the like can individually set their delay times by signals from the outside.

Further, a processor 8 is provided for controlling the delay time of the variable delay circuit 6 and the like, and the processor 8 is provided with the clock signal of the clock signal generator 7 and the discharge photodetectors 5, 5a, 5b.
Each detection signal is input and the variable delay circuit 6,6
They are connected to a and 6b so as to output control signals of delay time. The processor 8 includes variable delay circuits 6, 6a, 6b.
The delay time set at the beginning of each of the above (set so that the maximum value of the laser output is obtained at the start of operation) is stored, and the delay time set value is set in the variable delay circuit 6 etc. based on this value. The processing means for instructing is provided. After the operation of the laser amplifier device starts, when the elapsed time from the clock signal to the detection signal of the discharge photodetector 5 changes from the value at the start of operation, the difference is calculated and the delay time is calculated. The variable delay circuit 6 that corrects the command value
It is possible to perform the process of sending to. Note that the variable delay circuits 6a and 6b can perform the same processing.

Next, the operation will be described.

When the clock signal generator 7 is started, the clock signal is delayed by passing through the variable delay circuit 6 and 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 thus generated is repeatedly applied to the laser amplifier 1a. 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 at 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 by 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.
The generated laser light output is repeatedly applied to the laser amplifier 1b.

The relationship of the operation of the laser amplifier 1b with respect to the laser amplifier 1a is the same as that of the laser amplifier 1a with respect to the laser oscillator 1, and therefore the description thereof is omitted.

Although the delay time set in the variable delay circuit 6a has been schematically described above, this 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 the same as the delay time set in the variable delay circuit 6 as described above. 1 and laser amplifier
It is a value that includes the propagation time between 1a. However, there are generally individual differences in the ionization times of the thyratron 3 and the thyratron 3a. 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 condition of the laser amplifier device is kept constant, and
In order to obtain the maximum output of 1b, the processor 8 can be operated by an external means (not shown) to adjust the delay time of the variable delay circuit 6a and thereafter.

In this way, each laser amplifier 1a etc. is excited in accordance with the input of the pulsed laser light from the previous stage, and after the laser amplifier device starts operation, external operation of the thyratron 3a etc. Even if the ionization time of the thyratron 3a or the like changes due to the condition, that is, the change of the voltage applied to the cathode heater, or the change of the ambient temperature, the reservoir voltage, or the like, the processor 8 causes the delay time of the corresponding variable delay circuit 6a or the like to change. It is set and valued to compensate for the change. 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 cycle of the ionization time described above 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 is the clock signal generator 7
For each clock signal of, for example, based on the detection signal from the discharge photodetector 5a, the generation time of the excitation pulse applied to the laser amplifier 1a at that time is monitored, until the next clock signal when the fastest. The delay time of the variable delay circuit 6a can be reset. Therefore, the delay time setting of the variable delay circuit 6a or the like can track and correct the ionization time fluctuation of the perfect thyratron 3a or the like.

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 from the preceding stage of the subsequent laser amplifier 1a etc. Since the input timing and the variation between the excitation pulses are 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 ……
Discharge light detector, 6, 6a, 6b ... Variable delay circuit, 7 ... Clock signal generator, 8 ... Processor.

Claims (1)

[Claims] 1. A laser oscillator and a laser amplifier that are optically cascaded, a high-voltage pulse power source for laser excitation that is individually provided in the laser oscillator and the laser amplifier, and a trigger circuit of these high-voltage pulse power sources, respectively. A variable delay circuit which is placed in front and whose delay time is controllable, an oscillator which repeatedly supplies a pulse signal to each of these variable delay circuits, discharge light detection means for detecting the discharge light of each laser amplifier, and these discharge light Each detection signal of the detection means and the repeating pulse signal of the oscillator are input, and a processor that outputs a control signal to each of the variable delay circuits,
The processor commands the respective delay times to the respective variable delay circuits, and when a time difference fluctuation between the detection signal of the excitation current detecting means and the repetitive pulse signal of the oscillator is detected, the correction delay is corrected to correct the fluctuation value. An excitation control device for a laser amplifier device, comprising processing means for changing the time and sequentially instructing the corresponding variable delay circuit.