Study On Experimental Technology Of Medical Long-pulse Nd:YAG Laser

Recently, clinical experiments indicate that the pulse used in laser hair removal treatment has better not less than 50ms and can be adjusted according to patients' conditions to get high efficiency. Medical researches and clinical experiments also indicates that 1064nm Nd:YAG laser has the character of deep penetrability in skin, so it is widely used for skin disease therapy. And it can't be absorbed easily in large quantity by melanin so as to protect skin effectively. Except that laser energy density should be enough in treatment. So we chose long-pulsed Nd:YAG laser as our research object, and we studied long-pulsed Nd:YAG laser according to the datum of laser treatment presently. Some important results were achieved in this thesis as followings:1. In this paper we describe the laser's function to the biology and summarize the status of research of laser treatment in skin disease currently. Except that we also analyze and introduce the application and developing tendency of long-pulsed Nd:YAG laser in skin treatment.2. We expound the therapy and characters of flash lamp pumping of Nd:YAG laser and design strong pulses simmer circuit and small direct current high-voltage simmer circuit to lower the work voltage of main power and the loss of simmer circuit. Based on that the Nd:YAG laser outputted periodic long-pulses and the laser width could be adjusted between 2~200ms.3. We designed a system including all-trigger series arrangement of avalanche transistor high-speed Q-switching circuit, high-voltage stabilizing circuit and signal delaying circuit. This system is used on KD*P, the fall time of 3.8kV Vλ/4 is 8ns, highest work repetitive frequency is 20kHz; and fall time of 3kV voltage is about 8ns,it has steady operation at 50kHz high repetitive frequency.4. We did pumping experiments using series arrangement of double Xe lamps, series arrangement of double Kr lamps, single Xe lamp and single Kr lamp successively. Finaly using single Kr lamp to pump,when main power voltage is 300V,the laser is 20J. And Analyzing the problem of laser pulses which lowered slowly in experiments and providing methods to solve it.