Infrared interferometric systems

Infrared interferometric systems using a CO2 laser operating at a wavelength of 10.6 micrometers were investigated. Specific systems developed were the infrared laser unequal path interferometer (IRLUP), the IRLUPI with infrared computer generated hologram, the infrared common path interferometers such as the infrared point diffraction interferometer, and the infrared scatterplate interferometer. The above interferometers produce interferograms of equal optical path difference (OPD). Other types of common interferometers which provide interferometers of differential OPD were also developed. They are infrared lateral shearing interferometers, a germanium plane parallel plate, the Ronchi ruling, and the double grating lateral shearing interferometer. A pyroelectric vidicon was employed as an ac infrared detector with proper intensity modulation techniques. Chopping, panning, and phase variation of the interferogram modulated the interference pattern effectively for various types of interferometers. Germanium and zinc selenide optics were used for lenses and beamsplitters. A He-Ne gas laser was installed parallel to the CO2 beam for the ease of initial aligment. Test interferograms are shown using each interferometer.