JPS6331118B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laser oscillator, and particularly to a laser oscillator that performs Q-switch laser oscillation using a Q-switch element.

Generally, oscillation by a laser, especially a fixed laser, is a collection of irregular pulses, but by using a Q switch it is possible to oscillate it as a single pulse with a large repeat value. In this case, the Q switch lowers the Q of the optical resonator until the energy stored in the laser element reaches the maximum, and then improves the Q value when the stored energy reaches the maximum to obtain the maximum laser output. It is well known that when operating as a variable Q switch element, the peak value and pulse width of the resulting output laser pulse are proportional to the value of Q and the switching speed of the Q switch.

Conventionally, in a laser oscillator that performs this type of Q-switch laser oscillation, the laser element is excited by light emitted by discharge of an excitation discharge tube, that is, optical pumping. This continues even after the energy stored in the laser element reaches its maximum and the Q switch causes laser oscillation.

Therefore, the excitation energy corresponding to the emission waveform after laser oscillation becomes a loss, which reduces the excitation efficiency and promotes heating of the laser element.Furthermore, when this loss of energy is large enough, the energy for excitation corresponding to the emission waveform after the first laser oscillation is lost. This method has the disadvantage of causing unnecessary laser oscillation and inhibiting so-called single giant pulse laser oscillation, which is the original form of Q-switch laser oscillation.

An object of the present invention is to provide a laser oscillator capable of stably performing Q-switch laser oscillation by eliminating the above drawbacks by providing a circuit that intermittents the supply of excitation energy when supplying excitation energy to a laser element. There is a particular thing.

The oscillator of the present invention includes a laser element, a Q-switch circuit that causes the laser element to perform Q-switch laser oscillation, an excitation power storage circuit that stores excitation energy, and a Q-switch circuit that receives excitation energy from the excitation power storage circuit. an excitation circuit that excites the laser element in synchronization with the operation of the switch circuit; and an excitation power that stops the supply of excitation energy from the excitation power storage circuit to the excitation circuit at the same time as the laser oscillation starts due to the operation of the Q switch circuit. and a supply control circuit.

Next, details of the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a block diagram of a conventional general laser oscillator of this type. Laser element 1, laser output side reflector 2, laser total reflection mirror 3, polarizer 41 of Q switch circuit 4, and Q switch element 42
An optical resonator is formed. In addition to the polarizer 41 and Q-switch element 42 described above, the Q-switch circuit 4 includes a Q-switch element driver 43 that generates a drive voltage to drive the Q-switch element 42, and the energy stored in the laser element 1. When the maximum value is reached, laser oscillation is performed to generate a giant pulse 201.

The excitation circuit 5 provides the necessary energy to the laser element 1, and the excitation discharge tube trigger generator 52 outputs the output under the control of the operation control circuit 7, which has a built-in control circuit that controls the operation of each circuit. Then, a trigger pulse with the same repetition frequency as the laser pulse oscillation frequency is applied to the excitation discharge tube 51 via the trigger wire 53 to cause it to emit light at the repetition frequency of the trigger pulse, and this light energy is given to the laser element to store energy. Performs optical pumping for

The check coil CH ₁ is a check coil for suppressing the peak discharge current flowing through the excitation discharge tube 51.

The excitation power storage circuit 6 has a capacitor C _{1 and a DC power supply 61 for charging the capacitor C 1} , charges the capacitor C ₁ under the control of the operation control circuit 7 , and transmits this voltage through the choke coil CH _{1 .} The voltage is applied to the excitation discharge tube 61 of the excitation circuit 6.

FIG. 2 is an operation waveform diagram for explaining the operation of the laser oscillator in the conventional example shown in FIG.

The excitation discharge tube discharge light emission waveform becomes A with time t.
As shown in the figure, the waveform of the discharge current changes similar to the waveform of the discharge current, and the laser element 1 receives light energy from the discharge tube through light emission, and at the time to when this accumulated energy reaches its maximum, the Q switch circuit 4 oscillates the laser. Do this. The waveform of energy stored in the laser element 1 is shown in Figure B. The laser thus obtained is output as a giant pulse at to as shown in diagram C.

However, in this case, as is clear from Fig. 2, only part a of Fig. A of the luminous energy due to the discharge of the excitation discharge tube is utilized by the laser element.
Part b is not used and results in energy loss.
In other words, the energy stored in the laser element 1 continues to be B even after laser oscillation is performed at time to.
This results in energy being supplied as shown in part c in the figure, which leads to a decrease in excitation efficiency and unnecessary heating of the laser element.Furthermore, if the energy in part c is large enough, the laser oscillation is repeated after the first laser oscillation. This results in laser oscillation of a single giant pulse laser, which is the original form of a Q-switch laser.

FIG. 3 is a block diagram showing one embodiment of the present invention. Laser element 1', laser output side reflecting mirror 2',
A total reflection mirror 3' for laser, a Q switch circuit 4' consisting of a polarizer 41', a Q switch element 42', and a Q switch element driver 43' for performing Q switch operation, and a laser element 1' are operated by optical pumping. An excitation discharge tube 51' for excitation, a trigger wire 53' for triggering the excitation discharge tube 51', and an excitation discharge tube trigger generation for triggering the excitation discharge tube 51' via the trigger wire 53'. an excitation circuit 5' consisting of a pump 52', a choke coil _CH1 ' for suppressing the peak current flowing through the excitation discharge tube 51', a capacitor _C1 ' for storing excitation energy, and a DC power supply for charging this capacitor. 61', an excitation power supply control circuit that turns on and off the supply of excitation energy to the excitation discharge tube 51', which is made up of an excitation power storage circuit 6' including a gate turn-off thyristor 81, and a thyristor driver 82 for gating this thyristor. 8, a Q switch circuit 4', and an operation control circuit 7' that controls the operation of each of the above circuits.
The basic difference from the conventional example shown in FIG. 1 is that an excitation power supply control circuit 8 is added.

The excitation circuit 6' applies a trigger pulse voltage having the same repetition frequency as the desired laser oscillation frequency to the excitation discharge tube 51' from the excitation discharge tube trigger generator 52' via the trigger wire 53' to generate a discharge. Make it emit light. The choke coil CH ₁ ' is for suppressing the peak discharge current flowing through the discharge tube 51'.

The excitation discharge tube 51' of the excitation circuit 5' receives the necessary DC high voltage power from the excitation power storage circuit 6' via an excitation power supply control circuit 8 and a choke coil CH ₁ ', which will be described later. The excitation power storage circuit 6' consists of a capacitor _C1 ' and a DC power supply 61' for charging this capacitor.
The necessary excitation energy is supplied from C ₁ ' to the excitation discharge tube 51'.

The excitation power supply control circuit 8 includes a gate turn-off thyristor 81 and a thyristor driver 82 that supplies gate power to operate the thyristor.
is turned on when a positive current is applied to its gate, and turned off when a negative current is applied to its gate, and the turn-off operation can be performed in a short time of about a few μs. In the excitation power supply control operation, the excitation discharge tube trigger generator 52' of the excitation circuit 5' sends a high voltage trigger pulse to the excitation discharge tube 51 via the trigger wire 53' under the control of the operation control circuit 7'. At the same time, a gate voltage is sent from the thyristor driver 82 so as to turn on the gate turn-off thyristor 81 of the excitation power supply control circuit 8, causing the excitation discharge tube 51' to discharge light and excite the laser element 1'. When the energy stored in the laser element 1' is at its maximum, the Q-switch element driver 43' of the Q-switch element 42' of the Q-switch circuit 4' drives the laser element 1' to cause Q-switch laser oscillation. This is done by turning off the gate turn-off thyristor 81 and turning off the supply of excitation energy from the excitation power storage circuit 6'.

By performing such excitation power supply control operation, the capacitor of the excitation power storage circuit 6'
Excitation energy that becomes unnecessary after Q-switch laser oscillation can be stored in C ₁ ', and this excitation energy can be used for the next laser oscillation, resulting in stable single giant pulse oscillation. It will be useful in getting people to do this.

FIG. 4 is an operational waveform diagram for explaining the operation of the present invention. FIG. 4D shows the discharge light emission waveform of the excitation discharge tube 61', E shows the energy characteristics stored in the laser element 1', and F shows the laser output waveform. ,B
and corresponds to C. The discharge light emission waveform D shows that, as described above, the excitation discharge tube 51' receives a high-voltage trigger pulse from the excitation discharge tube trigger generator 52', and at the same time the gate turn-off thyristor 81 is turned on and the discharge tube emits light. The excitation of the laser element 1' is started, and at the time when the energy stored in the laser element 1' is at its maximum, the Q switch element 4 is turned on.
2' operates to perform Q-switch laser oscillation, and at this time, the gate turn-off thyristor 81 is turned off and the excitation discharge tube 51' also stops emitting light. Therefore, the energy for discharging and emitting light from the part d corresponding to the part b in the conventional example of _FIG . becomes possible.

FIG. 4E is a waveform diagram showing the state of energy stored in the laser element 1', that is, the excited state of the laser element 1', corresponding to the discharge light emission waveform D of the excitation discharge tube 51'. As is clear from the figure, due to the operation of the excitation power supply control circuit 8, there is no undesirable accumulation of energy after the period of Q-switch laser oscillation, and therefore the laser output is stable and high compared to the laser output in Figure 2C. A single giant pulse of F
is obtained.

Although the basic embodiment has been described above as one embodiment of the present invention, it is clear that the present invention can be applied to other modified examples as well. For example, instead of the gate turn-off thyristor 81, another bidirectional three-terminal thyristor may be used to turn on the gate.
The excitation discharge tube 51' may also be turned off.
By replacing the laser element 1' with a discharge tube containing gas as a laser medium and omitting the laser element 1', the present invention can be easily applied to a gas laser device that is excited by discharge pulses without detracting from the spirit of the present invention.

As explained above, the present invention eliminates loss of excitation energy and improves excitation efficiency by providing a simple circuit that intermittents the supply of excitation energy in correspondence with laser oscillation when supplying excitation energy to a laser element. However, there is an effect that unnecessary heating of the laser element can be suppressed and stable, high-output single giant pulse laser oscillation can be performed.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional laser oscillator, Fig. 2 is an operation waveform diagram showing the operation of a conventional laser oscillator, Fig. 3 is a block diagram showing an embodiment of the present invention, and Fig. 4 is a block diagram of a conventional laser oscillator. FIG. 3 is an operation waveform diagram showing the operation of the laser oscillator. In FIGS. 1 and 3, 1, 1'...
Laser element, 2, 2'... Laser output side reflecting mirror,
3, 3'... Laser total reflection mirror, 4, 4'... Q switch circuit, 5, 5'... Excitation circuit, 6, 6'...
Excitation power storage circuit, 7, 7'...operation control circuit,
8...Excitation power supply control circuit, 41, 41'...
Polarizer, 42, 42'...Q switch element, 43,
43'...Q switch element driver, 51,5
1'... Excitation discharge tube, 52, 52'... Excitation discharge tube trigger generator, 61, 61'... DC power supply,
81...Gate turn-off thyristor, 82...
thyristor driver.

Claims (1)

[Claims] 1 A laser element, a Q-switch circuit that causes this element to perform Q-switch laser oscillation, an excitation power storage circuit that stores excitation energy, and a system that receives excitation energy from this excitation power storage circuit and synchronizes with the operation of the Q-switch circuit. an excitation circuit that excites the laser element, and an excitation power supply control circuit that stops supplying excitation energy from the excitation power storage circuit to the excitation circuit simultaneously with the start of laser oscillation by the operation of the Q switch circuit. A laser oscillator characterized by comprising: