光学元件污染对红外光学系统信噪比的影响分析

红外光学系统直接暴露在外界热环境中,光学元件表面微粒污染的存在将降低红外光学系统的探测性能,严重时还可能会缩短其工作寿命。合理判断光学元件的污染容限并采取适当的镜面清洗及维护措施有利于红外光学系统的良好运行。介绍了红外光学系统中信噪比的计算方法,利用ASAP软件建立了典型红外光学系统的三维仿真模型,研究了信噪比随系统反射镜表面污染程度的变化规律,据此讨论了该红外光学系统中光学元件的污染容限,并分析了元件光学特性对光学元件信噪比的影响。研究结果表明,随着红外光学系统中光学元件表面污染程度的加重,系统信噪比将明显减低;当元件光学特性变差时,为保证低信噪比微弱信号的有效探测,必须严格控制光学元件表面污染微粒的覆盖率,使其表面洁净程度保持在更高的水平。

Influence of the optical components contamination on the signal to noise ratio in infrared optical systems

The infrared optical systems are usually exposed to the external thermal environment.The particulate contamination of the optical components will degrade the detection performances of infrared optical systems and even shorten the working life in some severe cases.To ensure the well operation of infrared optical systems,the contaminative capacity of optical components should be reasonably estimated and proper mirror cleaning and maintenance measures should be taken.The methods of calculating the signal to noise ratio(SNR) were introduced.The three-dimensional simulation model of typical infrared optical system was built by using ASAP software.The variations of SNR with the level of contamination on mirror were studied.On the basis of that,the contaminative capacity of optical components in infrared optical systems has been discussed.Furthermore,the influence of the optical properties of the elements on the SNR of optical components was analyzed.Experimental results indicate that the SNR will be reduced obviously with the increasing of contamination level on optical components.When the optical properties of components become worse,to ensure the effective detection of the weak signal with low SNR,the factional area coverage of particles on optical components should be strictly controlled,keeping the optical components on a higher cleanliness level.