红外光学系统中靠近探测器的光学元件通常处于低温环境中, 低温环境会使得光学元件表面薄膜的透射光谱发生漂移, 进而严重影响红外光学系统的成像质量。研究发现光谱漂移是由于系统中红外光学薄膜的折射率发生了改变。论文针对红外光学薄膜材料折射率温度特性开展了研究, 在光学薄膜理论基础上, 通过分析几种波长色散模型的特点, 提出了一种红外光学薄膜材料折射率温度特性的研究方法。该方法基于不同温度测得的透射率光谱, 通过光谱反演得到不同温度条件下光学薄膜材料的折射率, 并在Cauchy色散模型的基础上, 通过数据拟合分析, 能够得到红外光学薄膜材料的折射率温度/波长色散公式。采用该方法对PbTe、Ge两种典型红外光学薄膜材料折射率温度特性进行了分析研究, 验证了该方法的可行性。

Optical elements closed to photodetector always work in low temperature in infrared optical system, and the transmitted spectrum of the system would be shifted by the low temperature condition. This shift can affect the image quality of the system seriously. Some study have found that the reasons of the spectral shift are the change of the refractive index of the infrared thin-films in the system. In the paper, temperature characteristics of the infrared thin-films were studied. Based on the theory of optical thin film and analysis of several kinds of wavelength dispersion model, a new research on the temperature characteristic method of infrared thin film was put forward. With the method, the refractive index of infrared thin film at different temperature can be measured by spectral inversion according to the transmission spectra, and then, a formula for calculating refractive index of infrared thin film can be deduced based on the Cauchy dispersion model through data fitting analysis. The temperature characteristics of two kinds of infrared typical film materials(PbTe and Ge) were studied with the method, and the results verify the validity of the method.