使用红外干涉仪测量红外材料折射率

Measurements of Infrared Materials Refractive-index Using Infrared Interferometer

使用自行研制的泰曼型红外干涉仪测量红外材料的折射率.在干涉仪的测试臂中加一个旋转台,将被测件放在旋转台上旋转,在旋转过程中经过被测件的光程发生改变,导致干涉条纹发生移动,通过测量条纹的移动数和被测件的旋转角度来计算出被测件的折射率.测量结果显示,25°C时在10.6μm波段处锗单晶的折射率为4.003,硫系玻璃锗砷硒(GeAsSe)的折射率为2.494.折射率测量的误差在10-3量级,增加被测件的厚度会进一步提高折射率的测量准确度,待测红外材料的折射率越低,测量准确度越高.

The refractive index of infrared material is measured using the infrared Twyman-Green interferometer. By adding a rotation stage in the test arm,the OPD of the test piece placed on the stage is changed with the rotation and the interference fringe is shifted. The refractive index of the test piece can be calculated by the recorded values of rotating angle and shifting fringe. The result shows that the refractive index of germanium crystal is 4. 003 and the refractive index of GeAsSe is 2. 494 when the temperature is 25 ℃and the wavelength is 10.6 μm. The measurement error of the method is 10^-3 ,which indicates that the precision can be improved if the test piece is thicker or its refractive index is lower.