JPH02209780A - Q switch laser output device - Google Patents

Abstract

PURPOSE:To suppress the peak value of an initial pulse laser light even if the output energy of a pulse laser light is large by delaying by one pulse a modulation signal, ending it at the end timing of the signal to be supplied to a first driver, and driving a Q switch not driven by the first driver upon reception of the delayed modulation signal. CONSTITUTION:A modulation signal generator 42 has a function of passing a modulation signal during a period when a Q switch control outer signal becomes a low level to a first driver 43 and a delay circuit 44. The driver 43 receives the modulation signal to drive to open or close a Q switch 26. The modulation signal and a high frequency signal from a high frequency oscillator 46 are input to a pulse modulator 45. The modulator 45 passes the high frequency signal during a period when the modulation signal is a high level. Thus, the switch 26 is driven by the driver 43 upon reception of the modulation signal, the signal is delayed by one pulse by the delay circuit 44, ended at the same timing as the ending timing of the pulse modulation signal to be supplied to the driver 43, fed to a second driver 52, and a Q switch 27 is driven by the driver 51.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a Q-switched laser output device that obtains high-output pulsed laser light.

(Prior art) As a Q-switch laser output device, for example, the
There is a technique disclosed in Japanese Patent No. 17236. FIG. 5 is a configuration diagram of a Q-Sui Nochi laser output device of this technology. An excitation light source 2 is arranged in parallel to the solid-state laser medium 1, and a condenser 3 is arranged around the solid-state laser medium 1 and the excitation light source 2. Furthermore, reflecting mirrors 4.5 are arranged coaxially with respect to the longitudinal direction of the solid-state laser medium 1, respectively. An acousto-optic light modulator (hereinafter referred to as Q-sui-sochi) is provided between the solid-state laser medium 1 and the reflecting mirror 5.
6 is placed. This Q switch 6 forms an ultrasonic phase diffraction grating 8 in the ultrasonic self, and each reflecting mirror 4, 5
It generates and stops the optical resonance effect between the ultrasonic self and the electroacoustic transducer 9.

On the other hand, 10 is a high frequency driver. A Q-switch control external signal as shown in FIG. 6 is input to this high-frequency driver 10 and sent to a modulation signal generation circuit 11. When this modulation signal generation circuit 11 receives a Q-switch control external signal, it sends a modulation signal whose pulse width W changes sequentially as shown in FIG. 6 to the pulse modulation circuit 12 during the low level period of this Q-switch control external signal. do. In this state, a high frequency signal is input from the oscillator 13 to the pulse modulation circuit 12, so the pulse modulation circuit 12 transmits the high frequency signal to the electroacoustic transducer 9 through the high frequency amplifier circuit 14 during the period when the modulation signal is at a high level. supply

When a high frequency signal is supplied to the electroacoustic transducer 9 and an ultrasonic phase diffraction grating is formed within the ultrasonic self, optical resonance does not occur between the reflecting mirrors 4 and 5, and the solid-state laser Energy is stored in medium 1. and,
During the period when no high frequency signal is supplied to the electroacoustic transducer 9,
When the ultrasonic phase diffraction grating is no longer formed in the ultrasonic self, the Q switch 6 is opened and optical resonance occurs between the reflecting mirrors 4 and 5. As a result, Q-switched pulsed laser light P is output.

By the way, as shown in FIG. 6, the pulse width W of the modulation signal is gradually expanded and is finally controlled to a pulse width W''. Therefore, the peak value of the Q-switched pulsed laser beam P is suppressed in the initial stage. The reason for this is that when outputting Q-switched pulsed laser light at intervals shorter than the fluorescence lifetime of the laser medium, the period until the first Q-switched pulsed laser light is output is long; The stored energy is larger than that after that. Therefore, if the Q switch 6 is opened with a wide pulse width W' in this state, the peak value of the first pulsed laser beam P will become large. .

Therefore, in Kawamei, the peak value of the Q-switched pulsed laser beam P is reduced by narrowing the pulse width W.

However, when trying to obtain a Q-switched pulsed laser beam with a large output using the above device, even if an ultrasonic self-diffraction grating is generated in the Q-switch 6, it is not possible to completely stop the optical resonance effect, and the action as a Q-switch cannot be completely stopped. become unable to do so.

(Problems to be Solved by the Invention) As described above, when the output energy of the pulsed laser light becomes large, the Q-switch operation becomes impossible and CW laser light is output.

SUMMARY OF THE INVENTION An object of the present invention is to provide a Q-switch laser output device that can suppress the peak value of the first pulsed laser beam even if the output energy of the pulsed laser beam is large.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a structure in which: At least two Q switches arranged respectively, a modulation signal generation circuit that generates a modulation signal for on/off control of these Q switches, and a modulation signal generating circuit that receives the modulation signal from the modulation signal generation circuit to control one of the Q switches. a first drive circuit that drives either one; a delay circuit that delays the modulation signal from the ☆ tone signal generation circuit by one pulse and ends it at the same timing as the end timing of the modulation signal supplied to the first drive circuit; Q that is not driven by the first drive circuit after receiving the modulated signal delayed by the delay circuit
This is a Q-switch laser output device that attempts to achieve the above objective 1'' by including a second drive circuit that drives the switch.

(Function) By providing such means, the first drive circuit receives the modulation signal from the modulation signal generation circuit and selects a predetermined Q switch of at least two Q switches arranged between the laser medium and each mirror. Drive the Q switch. On the other hand, the delay circuit receives the modulation signal from the modulation signal generation circuit, delays it by one pulse, and converts it into a modulation signal that ends at the same timing as the end timing of the modulation signal supplied to the first drive circuit.
Send to drive circuit. However, this second drive circuit receives the modulation signal delayed by the delay circuit and drives the Q switches that were not driven by the first drive circuit among the Q switches. As a result, the first pulsed laser beam is output by turning off a predetermined Q switch among the Q switches,
Its peak value will be suppressed.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a Q-switched laser output device. In the figure, 20 is a solid-state laser medium, and two excitation light sources 21 and 22 are arranged in parallel in this solid-state laser medium. These solid-state laser medium 21 and each excitation light source, 21.
22 is surrounded by a condenser 23. In addition, an optical resonator (;3
A high reflection mirror 24 and an output mirror 25 are respectively arranged.

Q-switches 26 and 27 are arranged between the solid-state laser medium 20 and the high-reflection mirror 24 and between the solid-state laser medium 20 and the output mirror 25, respectively. These Q-switches 26, 27 each consist of an ultrasound cell 28, 29 and an electroacoustic transducer 30, 31. In addition,
32 and 33 are ultrasonic phase gratings formed by supplying high frequency signals.

On the other hand, 40 is a driver circuit, and this driver circuit 40 is supplied with a Q-switch control external signal and a pulse signal from a pulse signal generation circuit 41 as shown in FIG. These Q-switch control external signals and pulse signals are sent to a modulation signal generation circuit 42, and this modulation signal generation circuit 42 passes the modulation signal during the period when the Q-switch control external signal is at a low level. Drive circuit 4
3 and a delay circuit 44. The first drive circuit 43 receives a modulation signal and drives the Q switch 26 to open and close. Specifically, a pulse modulation circuit 45 is provided, and the pulse modulation circuit 45 receives a modulation signal and a high frequency signal from a high frequency oscillator 46. is now entered. This pulse modulation circuit 45 is configured to pass a high frequency signal during a period when the modulation signal is at a high level. Then, this high frequency signal is amplified by the high frequency amplification circuit 47 and transmitted to the electroacoustic transducer 3 of the Q switch 26.
0.

On the other hand, the delay circuit 44 has the function of delaying the modulation signal by one pulse and modulating it (ending the word) at the same timing as the end timing of the modulation signal supplied to the first drive circuit 43. The configuration is as shown in Figure 3. That is, a 1-bit shift register 48 is provided, and a Q-switch control external signal is input to this 1-bit shift register 48, and a pulse signal is input to the clock input terminal ek. An OR gate 50 is connected to the output terminal of this 1-bit shift register 48 via one input terminal of an OR gate 49.A Q-switch control external signal is input to the other input terminal of the OR gate 50. A pulse modulation signal is input to the other input terminal of the OR gate 50, and the output of the OR gate 50 becomes the delayed output of the delay circuit 44 and is sent to the second drive circuit 51. The Q switch 27 is driven to open and close in response to the modulated signal. Specifically, a pulse modulation circuit 52 is provided, and the delayed modulation signal and the high frequency signal from the high frequency oscillator 53 are transmitted to the pulse modulation circuit 52. This pulse variation circuit 52 is configured to pass a high frequency signal during the period when the modulation signal is at a high level.Then, this high frequency signal is subjected to high frequency amplification. The signal is amplified by a circuit 54 and supplied to the electroacoustic transducer 31.

Next, the operation of the apparatus configured as described above will be explained.

When the Q-switch control external signal changes to low level while the pulse signal is output from the pulse signal generating circuit 41 and is sent to the modulating signal generating circuit 42, the modulating signal generating circuit 42 changes the Q-switch controlling external signal to low level. The pulse signal is passed during the period during which it is sent as a modulation signal to the pulse modulation circuit 45 and the delay circuit 44. here,
The pulse modulation circuit 45 passes the high frequency signal from the high frequency oscillator 46 during the period when the modulation signal is at a high level. This high frequency signal is then amplified by a high frequency amplification circuit 47 and supplied to the electroacoustic transducer 30 of the Q switch 26. Thereby, an ultrasonic phase diffraction grating 32 is formed in the ultrasonic cell 28 when a high frequency signal is supplied.

Meanwhile, at the same time, the modulation signal from the modulation signal generation circuit 42 is sent to the delay circuit 44 and delayed by one pulse. That is, the 1-bit shift register 4 of the delay circuit 44
Reference numeral 8 outputs the Q-switch control external signal after being delayed by one pulse of the pulse signal, that is, the modulation signal, as shown in FIG. Then, by sending this register output and the Q switch control external signal to the OR gate 49, the four OR gates send a signal that is at a low level during the tl-12 period to the OR gate 50. However, this ORGATE 5
Since a modulation signal is input to the other input terminal of 0, the OR gate 50 outputs a modulation signal that is delayed by one pulse and has the same end timing as the pulse modulation signal.

As a result, the pulse modulation circuit 51 generates the high frequency oscillator 52 during the period when the modulation signal from the delay circuit 44 is at a high level.
Pass high frequency signals from. Then, this high frequency signal is amplified by the high frequency amplifier circuit 54 and the Q switch 2
It is supplied to the electroacoustic transducer 31 of No. 7. Thereby, an ultrasonic phase diffraction grating 33 is formed in the ultrasonic cell 29 when a high frequency signal is supplied.

However, the timing at which each of the Q switches 26 and 27 opens is as shown in FIG.
Next, both Q-switches 26 and 27 open synchronously. Here, since the solid-state laser medium 20 is excited by the two excitation light sources 21 and 22, the energy accumulated in the solid-state laser medium 20 is large. In other words, when only the Q switch 26 is open, the other Q switch 27 alone cannot keep the light closed, and light continues to leak through the Q switch 27. As a result, optical resonance occurs between the high reflection mirror 24 and the output mirror 25, and as a result, pulsed laser light is output when the Q switch 26 is in the r3n position.

However, at this time, the Q switch 27 is not completely open and a loss occurs, so the peak value of the pulsed laser beam is suppressed. From the next timing, both Q-switches 26 and 27 will synchronize and open at predetermined intervals.
The peak value of the pulsed laser beam remains constant.

In the embodiment described above, the Q switch 26 is driven by the first drive circuit 43 in response to the modulation signal, and the current signal is delayed by one pulse by the delay circuit 44, and the first drive circuit The pulse change supplied to the Q switch 43 is terminated at the end timing of the four signals and the t4-timing, and is sent to the second drive circuit 51.
7, the peak value of the brightest pulsed laser beam can be suppressed even when a high-output pulsed laser beam is output using a Q switch. However,
By adjusting the period of the modulation signal, etc., the peak values of all pulsed laser beams can be made the same.

Therefore, high output pulsed laser light can be obtained using the Q switch.

It should be noted that the present invention is not limited to the one embodiment described above, and may be modified without departing from the spirit thereof. For example, Q
The switches 26 and 27 may be placed together between the high-reflection mirror 24 and the solid-state laser medium 20, or between the output mirror 25 and the solid-state laser medium 20. Furthermore, the number of Q-switches is not limited to two, and the number of Q-switches may be arranged in accordance with the peak value of the pulsed laser beam.

[Effects of the Invention] As detailed above, according to the present invention, 1. It is possible to provide a Q-switch laser output device that can suppress the peak value of the first pulsed laser beam even if the output energy of the pulsed laser beam is large.

[Brief explanation of the drawing]

1 to 4 are diagrams for explaining an embodiment of a Q-switched laser output device according to the present invention, in which FIG. 1 is a configuration diagram, FIG. 2 is an operation timing diagram, and FIG. FIG. 4 is a basic configuration diagram of the delay circuit, FIG. 4 is an operation timing diagram of the delay circuit, FIG. 5 is a configuration diagram of a conventional device, and FIG. 6 is an operation timing diagram of the same device. 20...Solid laser medium, 21.22...Excitation light source, 23...Concentrator, 24...High reflection mirror, 25...
Output mirror, 26.27...Q switch, 28.29...
・Ultrasonic cell, 30.31... Electroacoustic transducer, 40
... Driver circuit, 41 ... Pulse signal generator, 4
2... Modulation signal generation circuit, 43... First drive circuit,
44...Delay circuit, 45...Pulse modulation circuit, 46
... High frequency oscillator, 47 ... High frequency amplifier circuit, 48
... 1-bit shift register, 49.50 ... OR gate, 51 ... second drive circuit, 53 ... high frequency oscillator, 54 ... high frequency amplifier circuit.

Claims (1)

[Claims] at least two Q switches disposed respectively between one end face of the laser medium and one of the resonator mirrors and between the other end face of the laser medium and the other resonator mirror, and turning on these Q switches. - A modulation signal generation circuit that generates a modulation signal for performing off control, a first drive circuit that receives a modulation signal from the modulation signal generation circuit and drives one of the Q switches, and the modulation signal. a delay circuit that delays the modulation signal from the generation circuit by one pulse and ends the modulation signal at the same timing as the end timing of the modulation signal supplied to the first drive circuit; A Q-switch laser output device comprising: a second drive circuit that drives a Q-switch that is not driven by the first drive circuit.