The Thermal Damage Research Of Optical Materials Under Millisecond-pulsed Laser Irradiations

The thermal damage of high energy laser has important application in metal and semiconductor materials of modern time industry and military, such as laser incision, laser jointing, laser stiletto. The technique of using laser thermal damage to melt or boil away port of materials and then cooling fuse is called laser jointing. High-speed assistant airflow blows the melted or boiled materials in order to form incision or aperture, which is defined laser incision or laser stiletto. Laser has incomparable power in weapon manipulative system, high power laser weapon can destroy airplane or tank in a millisecond, and can demolish the exploring portion of the missile being accurately controlled and guided.At the present time, many domestic and overseas researchers have investigated laser thermal damage under nanosecond-pulsed, but there has been few report of laser thermal damage under millisecond-pulsed laser irradiations. The thermal damage" about melt and vapor under millisecond-pulsed laser irradiate to some semiconductor materials and metal materials has been investigated in this thesis in details. Workout a c program which based on the sutra Fourier thermal conduct equation, different limit condition, utilize the finite difference method and obvious thermal capacity under one dimensional .The temperature of some semiconductor materials and metal materials has been described. The main results have been summarized as follows:1 .The factors that affect the damage conformation and damage threshold have been studied, and damage mechanism has been analyzed in the thesis. This thesis also extreme a currency mathematic model which descriptive materials melt and vapor process.2. We developed the obvious thermal capacity which only used to descriptive melting process to vapor process. For the first time utilize it to study vapor process.3. Workout a simple and high effect numerical program which utilize the finite difference method and obvious thermal capacity under one dimensional.4. The temperature of semiconductor materials (such as Silicon and Germanium) and optic materials (such as Aluminum Silver Copper and Titanium) have been calculated, and the thermal damage threshold of one-dimensional space has been gained.5. Particular analyze the parameter of the laser reflect time, the laser power density, thermal absorption coefficient, thermal conductivity affect the distributing of temperature field and the thermal threshold of melt and vapor.The data of temperature and thermal damage threshold for metal and semiconductor materials, which have been calculated in this thesis, will offer essential academic reference.