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为深入分析高重复频率CO2激光对HgCdTe晶体的损伤机理,开展了高重复频率CO2激光对HgCdTe晶体的温升实验,测得了不同激光重复频率(1、5、10kHz)下HgCdTe晶体的温升过程,建立了高重复频率CO2激光辐照HgCdTe晶体的理论模型,分析了激光重复频率对晶体温升特性的影响;利用ANSYS有限元软件计算了热损伤时HgCdTe晶体的温升值和热应力大小,并结合损伤形貌分析了激光热应力对HgCdTe晶体损伤的影响。研究结果表明,高重复频率CO2激光长时间辐照下,晶体表面温度随着辐照时间的增加而升高,辐照10s时,Hg0.826Cd0.174Te晶体基本达到热平衡,热平衡温度为77℃;重复频率大于1kHz时,激光重复频率的大小对HgCdTe晶体温升特性的影响较小,晶体表面温度主要由激光平均功率密度来决定;激光热应力对HgCdTe晶体的损伤特性影响较小,Hg0.826Cd0.174Te晶体熔化时的最大热应力为5×107Pa,该值远小于晶体的极限应力。该研究将对高重复频率CO2激光在激光防护等方面具有一定的参考价值。
In order to further analyze the mechanism of HgCdTe crystal damage caused by high repetition rate CO2 laser, the temperature rising experiment of HgCdTe crystal with high repetition rate CO2 laser was carried out. The temperature rising process of HgCdTe crystal with different laser repetition frequency (1, 5 and 10 kHz) , The theoretical model of HgCdTe crystal irradiated by high repetition rate CO2 laser was established and the influence of laser repetition frequency on the temperature rise characteristics was analyzed. The temperature rise value and thermal stress of HgCdTe crystal were calculated by ANSYS finite element software Combined with the damage morphology, the influence of laser thermal stress on the damage of HgCdTe crystal was analyzed. The results show that under the condition of high repetition rate CO2 laser irradiation for a long time, the crystal surface temperature increases with the increase of irradiation time. At 10 s irradiation, the crystal of Hg0.826Cd0.174Te reaches the thermal equilibrium basically, and the thermal equilibrium temperature is 77 ℃. When the repetition frequency is greater than 1 kHz, the laser repetition frequency has little effect on the temperature rise characteristics of HgCdTe crystals. The temperature of the crystal surface is mainly determined by the laser average power density. Laser thermal stress has little effect on the damage properties of HgCdTe crystals. Hg0.826Cd0 .174Te crystal melting maximum thermal stress of 5 × 107Pa, the value is far less than the ultimate stress crystal. This research will be of certain reference value to the high repetition rate CO2 laser in laser protection and so on.