基于洛伦兹模型的红外薄膜材料光学常数拟合及应用

在中长波红外区域,通常使用的镀膜材料都存在相当大的色散和一定的吸收。就目前的测试技术来说,确定这些材料的色散和吸收相当困难。试验基于洛伦兹谐振子模型对热蒸发制备的锗、硫化锌以及稀土氟化物薄膜的红外透射光谱进行拟合,得出这些材料在中长波红外区的光学常数。使用锗、硫化锌和稀土氟化物分别作为高折射率层(H)、中间折射率层(M)和低折射率层(L),设计并制备了从6.8μm~15μm的锗窗口宽带增透膜系,测量结果完全可以满足光机系统的要求。

The fitting and application of optical constants of infrared coating materials based on Lorentz oscillator model

The common evaporation coating materials have great dispersion and certain absorption in middle and long wave infrared region.It is rather difficult to determine the optical constants of these materials by the common measurement.The optical constants of evaporated films,such as germanium,zinc sulphide,rare earth fluoride,etc,had been obtained by fitting the transmission spectrum based on Lorenz oscillator model.Germanium,zinc sulphide and rare earth fluoride films were used as the high refractive index layer(H),middle refractive index layer(M) and low refractive layer(L) respectively.Broad band antireflective coating for germanium window from 6.8μm to 15μm had been designed and fabricated.The measured transmission result could satisfy the requirement of optical mechanical system.