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强激光辐照红外热像系统时,可造成系统的干扰和破坏,激光的波长不同,对系统的破坏效果也不同.为了保护红外系统窗口以及提高窗口的透过率,红外窗口广泛沉淀类金刚石(DLC)薄膜.当入射的激光波长位于红外系统响应波段外时,激光对系统的破坏首先是激光对DLC薄膜的破坏.以波长为1·06μm的激光为例,研究了脉冲激光对DLC薄膜的损伤机理,建立了DLC薄膜的热冲击效应模型,并通过求解热传导和应力平衡方程,得出了薄膜的温度场和应力场分布.理论分析表明,热应力破坏在脉冲强激光对DLC膜的损伤机理中占主导地位.当辐照能量密度为E0=100mJ·cm-2时,在薄膜表面距光斑中心约40μm区域内的压应力明显超出其断裂强度,将造成膜层的剥离、脱落.理论分析与实验结果基本相符,表明建立热冲击效应模型的正确性.
Strong laser radiation infrared thermal imaging system, can cause interference and destruction of the system, the laser wavelength is different, the destruction of the system is also different.In order to protect the infrared window and improve the transmittance of the window, the extensive precipitation of infrared window diamond (DLC) film.When the incident laser wavelength is outside the infrared system response band, the laser damage to the system is firstly caused by the laser damage to the DLC film.With the laser wavelength of 1.06μm as an example, the effect of pulsed laser on the DLC film , The thermal shock effect model of DLC film was established, and the temperature field and stress field distribution of the film were obtained by solving the heat conduction and stress balance equation. The theoretical analysis shows that the thermal stress is destroyed when the laser pulse impinges on the DLC film The damage mechanism is dominant.When the irradiation energy density is E0 = 100mJ · cm-2, the compressive stress in the area of about 40μm from the center of the film obviously exceeds the rupture strength, which will cause the peel and peel off of the film. The theoretical analysis is in good agreement with the experimental results, indicating the correctness of establishing the thermal shock effect model.