This project belongs to the field of laser technology, which involves the major of crystal and optoelectronic devices. In order to meet the demands for high temperature stability of laser system applied for some significant national projects such as manned spaceflight, lunar exploration and the Beidou navigation, and the demands for sophisticated laser system applied for national defense security, a series of work concerning the problem of high temperature stability of electro-optical Q-switched laser system were carried out in our project. This project confirmed, theoretically andempirically, that the root reason for the weakness of temperature stability of LN Q-switches is the stress in the crystal, and proposed that the key to develop high temperature stability of electro-optical Q-switch is to reduce the internal and external stress, thus showed clearly the direction issue of the research. This project proposed that through annealling the crystal blank with long-time low temperature in lithium rich atmosphere, crystal stress could be substantially decreased. Hence, higher crystal extinction ratio can be reached, so the problem of crystal coloring and solid solution shed were also solved. Moreover, the "flexible assembly" technology is developed, which means the device of electro-optical Q-switch could work without debugging the stress any more. That technology can solve the problem of the uneven force of the crystal assembly thoroughly, and at the same time increases the temperature stability and the quality of laser output spot after the Q-switch assembly considerably.

Based on the technology of high performance electro-optic Q switch, a series of laser system products possessing high temperature stability were developed independently, which can be used in such some complex conditions as aviation, aerospace, naval vessel and national defense etc. Furthermore, it achieved the mass production and the success rate of single test under high and low temperature was over 90%. From 2009 to 2011, the output value and the profit of the laser products from this project have achieved 141.216 million yuan and 87.786 million yuan respectively. The equipment based onthe product of this project were extensively applied to the telemetry control of launch vehicle, the air vehicle's collision avoidance and others measurement, which played an important role in implementation of major national projects such as manned spaceflight, lunar exploration project and Beidou satellite navigation etc. Meanwhile, batch application in the field of national defense has made great contributions to the national defense security.