The study of the influence of the changes of laser parameters on the temperature field distribution of PbS detector irradiated under 2.79μm mid-infrared laser has important reference value. In this paper, the theoretical simulation of a typical PbS detector irradiated by a 2.79μm mid-infrared laser is carried out by using the Finite Element Analysis method (FEA). The maximum temperature of PbS detector irradiated by 2.79μm mid-infrared laser with different laser parameters is investigated. The maximum temperature on the photosensitive surface of the PbS detector under different conditions is obtained by adjusting the spot radius, pulse width, and repetition frequency of the simulated pulsed laser. The effects of the changes of spot size, repetition frequency and pulse width on the maximum temperature of the photosensitive surface are investigated. The simulation results show that under the same energy density irradiation condition, the maximum temperature of the photosensitive surface decreases with the increase of the spot radius and pulse width. Under the condition of the same spot radius and pulse width, the higher repetition frequency can make the maximum temperature of photosensitive surface reach a higher temperature. This work gives the law of the temperature changes of the photosensitive surface caused by changing the laser parameters, which is helpful to improve the damage resistance of PbS detector to high power 2.79μm mid-infrared laser step by step.
The deep ultraviolet optical thin films play an important role in excimer lasers, deep ultraviolet lithography machine and other laser systems. In this paper, the experiment on damage in HfO2/ SiO2 high reflective film irradiated by 248nm ultraviolet excimer laser was carried out. And the high reflection film is coated with a layer of SiO2 as a protective film. The damage morphology and depth of the samples were observed and analyzed by means of DIC microscope and surface profiler system. In this experiment, the laser-induced damage threshold of HfO2/ SiO2 high reflective film coated with SiO2 protective film was calculated by zero damage probability. Based on the surface characteristics of the damage points, we established the model to analyze the damage mechanism of the high reflectance film by using Finite Element Method(FEM). The experimental results show that the damage threshold of 248nm excimer laser to the highly reflective film is 3.086J/cm2. When the incident laser energy is 3.33J/cm2, stress damage appears on the surface of the highly reflective film. With the increase of laser energy, the high reflective film will appear melting damage and corrugated damage.
In this paper, the damage characteristics of MgF2 window material were investigated by building a 193 nm UV excimer laser damage experimental system under different laser fluences of 193 nm excimer laser. The damage morphology was also observed by differential phase contrast microscopy (DIC). The damage mechanism of 193 nm excimer laser irradiated MgF2 window material was investigated. Finite element simulation experiments were also conducted for the defective MgF2 window material. The distribution of temperature and stress fields in the 193 nm UV laser irradiated MgF2 window material was numerically analyzed using the finite element method. The results show that when the laser irradiates the MgF2 window material, the damage threshold of the rear surface of the window material is 2.523 J/cm2 and the damage threshold of the incident surface is 9.74 J/cm2, that is, the rear surface is damaged before the incident surface. At the same time, the rear surface damage profile increased catastrophically with the growth of irradiated laser energy, while the incident surface damage profile increased linearly with the growth of irradiated laser energy. The main factor causing the damage to the window material is the damage caused by the defects contained in it, which causes stress damage to the window material during laser irradiation.
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