Abstract:Monocrystalline silicon is widely used in the field of photoelectric systems, and it is easy to cause its thermal damage and change of performance under the action of laser. For the urgent needs of high-precision laser weapons and laser fine processing industry, the thermal damage of monocrystalline silicon irradiated by pulse train of millisecond laser andthe relationship among the laser energy density, number of pulses and other important parameters of thermal damage were analyzed, and the damage law and mechanism were explored. Thermal damage of monocrystalline silicon by pulse train of millisecond laser was studied from both simulation and experimental aspects. Based on the heat conduction equation, a thermal damage model of monocrystalline silicon irradiated by pulse train of millisecond laserwas established, finite element and finite difference methods were used to solve temperature field of monocrystalline silicon treated by pulse train of millisecond laser. The equivalent specific heat capacity was introduced into the model to deal with the phase change after melting and vaporization, and the temperature rise of the model was corrected. The temperature measurement system of millisecond pulse laser damage monocrystalline silicon was constructed, and the high-precision spot temperature meter was used to measure the laser irradiation center point temperature in real time. Research indicated that when a pulsed laser is applied to monocrystalline silicon target, the center point of the laser irradiation and the radial and axial positions have a temperature accumulation effect, and the radial temperature rise range is much larger than the axial direction; With the increase of laser energy density, the temperature accumulation effect is significant; As the number of pulses increases, the melting time of monocrystalline silicon and the time from the melting point to the normal temperature are lengthened; when the number of laser pulses is increased to 90;The thermal damage threshold of monocrystalline silicon decreases to 73.8% of the single pulse damage threshold; When the number of pulses increases, the damage area of monocrystalline silicon increases. Comparing the experimental and simulation results, it can be seen that the laws of the two aspects are basically the same. The simulation model can reasonably describe the process of millisecond pulse laser damage to monocrystalline silicon.