高重复频率CO_2激光重复频率大小对HgCdTe晶体温升及损伤特性影响分析

Analysis of Temperature and Damage Characteristics of HgCdTe Crystal on Repetition Frequency of CO_2 Laser

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 research damage mechanism of HgCdTe crystal irradiated by high repetition frequency CO2 laser. Temperature experiment of HgCdTe crystal irradiated by high repetition frequency CO2 laser is conducted, and temperature rising progress of HgCdTe crystal irradiated by different repetition frequency CO2 laser （1, 5, 10 kHz） are measured. Theoretical model of HgCdTe crystal irradiated by high repetition frequency CO2 laser is developed, and the impact of laser repetition frequency on temperature characteristic is analyzed. The impact of thermal stress on damage characteristic is analyzed basing on scanning electron microscope （SEM） damage morphology and the value of temperature rising and thermal stress calculated by ANSYS. The research results show that temperature of the crystal irradiated by high repetition frequency CO2 laser gradually rise with increasing of irradiation time, and thermal equilibrium should have been attained on the Hg0.826Cdo174Te crystal when irradiation time is 10 s. When repetition frequency is more than 1 kHz, the temperature mainly depends repetition frequency. The maximum thermal stress value of which is less than the ultimate stress. The high repetition frequency CO2 laser on laser average power density, and doesn＇ t depend on is 5× 10^7Pa when Hg0.826Cd0.174Te clszstal surface melts, the conclusions have a reference value for laser protection on