Study On Repetition Electrooptical Q-switching Nd:YAG Lasers

Recent years, laser medicine in vascular disease and dermopathy have enormousdevelopment, and researchs indicated that repetition Q-switch Nd:YAG laser hasextensive prospect. The double-pulsing Q-switch Nd:YAG laser (1064nm or 532nm)can cure dermopathy, and the repetition Q-switch Nd:YAG laser can cure vasculardisease. According to developing of laser technology and laser medicine, we presentthe technical scheme of how to increase the energy and peak power and shorten pulsewidth of the double-pulse laser and series-pulse laser. We designed new electroopticQ-switch circuit. By applying KD*P, KTP and Xe-lamp, We develop double-pulsingfrequency Q-switch Nd:YAG laser and repetition Q-switch Nd:YAG laser. Both lasershave great use value. The main research works of this paper are as follows:1,Theoretical analyzing the relation of main parameter with periodic inrepetition laser, and analyzing the stability of repetition laser system.2,Design a Q-switch circuit with transistor and tube. The principle is using thefast breakover of avalanche transistor drive the electron tube. The full time of 4200Vvoltage is about 20ns. The circuit can normally work under 100kHz frequencies.Design an extra fast Q-switch circuit by series arrangement of avalanche transistor.The full time of 4200V voltage is about 5ns. The circuit and the transistor are work oncritical state, so the circuit only can work under 1kHz frequencies. Design a Q-switchcircuit by method of multipath trigger of series arrangement of avalanche transistor.Present a new design method that design different Q-switch circuit according to theleak current of transistor. The circuit can work normally under 50kHz frequencies.And the full time of 4200V voltage is about 10ns. This paper also design severalsupport circuits of Q-switch circuit including current foldback circuit, interface circuit,drive circuit, and negative feedback stabilivolt circuit.3,Realized normal operating of double-pulsing frequency Q-switch Nd:YAGlaser. By experiment generalize the optimum double-pulsing space is about 120μs.Obtain high outputting laser energy greater than 700mJ. Realized normal operating ofreprtition Q-switch Nd:YAG laser. And obtain the outputting laser of 50～300μs pulseperiodic time.