Design And Research For Q-Switched Nd:YAG Laser Control System

With the development of laser medicine, Q-switched Nd:YAG laser system has been widely used in several fields of medicine, and the laser technology of Q-switched Nd:YAG in medicine has also achieved great development. The Q-switched Nd:YAG laser system used electro-optical Q-switched technology which made laser energy immediately release, the laser energy was absorbed through corresponding skin pigments and penetrated through epidermis effectively. Pigment organization absorbed the laser energy and became small particles which could be taken away by macrophages, these pigments smeared out and disappeared, achieved the pigment-wiping out effect.The following conclusions have been drawn from clinical trials: 1064nm wavelength Nd:YAG laser was used for removal of black or blue pigmentation such as nevus of Ota, coffee spots, freckles, tattoos and eyebrow tattoos[1, 2]; 532nm wavelength Nd:YAG laser was used for removal of red or brown pigmentation such as PWS and shallow coffee-color flecks[3]; The long-pulse 1064nm wavelength Nd:YAG laser was used for treatment for capillary expansion or varicose veins[4].In this thesis, the laser-tissue interaction and development of medical lasers have been introduced, the design plan of Q-switched Nd:YAG laser control system has been expounded and the key problems for the design and research have been analyzed first, then corresponding solutions and Q-switched Nd:YAG laser system control system has been presented. Accordingly the resolutions to the problems said above have been brought forward, which were demonstrated as follows:(1) Q-switched and Non Q-switched mode laser have been achieved by controlling Q Switch.(2) 532nm and 1064nm wavelength laser have been achieved by controlling Wavelength Change.(3) Double MCUs has been used in control system: the primary MCU was responsible for communication with interface and control of the secondary MCU. The secondary MCU was responsible for controlling laser system and state feedback.(4) TFT LCD display with touch screen has been used to operate easily.(5) The anti-jamming on the control unit circuit and final test for the laser control system have been analyzed.(6) The control system has been successfully applied in actual products.