Design of Far-Infrared Interferometer at 10.6μm

The design and system performance of an far-infrared interferometer is presented. A CO2 laser is used as a light source operating at a 10.6 mum wavelength. A He-Ne laser is introduced into the interferometer to solve problems concerning with alignment. The instrument is capable of testing rough aspheric surfaces. It can be used to evaluate the refractive index deviation in the infrared materials too. The measuring error (RMS) of the interferometer is less than lambda/200 (lambda = 10.6 mum).