Novel moving cat's-eye-pair interferometer

A novel type of cat's-eye interferometer, the novel moving cat's-eye-pair interferometer, is presented. It has neither tilt nor shearing problems. It consists of one moving cat's-eye-pair (MCEP), i.e. two identical cat's-eye retro-reflectors fixed together back to back in a rigid structure as a single moving element, four fixed plane mirrors and one beam-splitter. The optical path difference (OPD) is created by the straight reciprocating motion of the MCEP, and the OPD value is eight times the displacement of the MCEP. The new interferometer is suitable for very-high resolution Fourier transform spectrometers for any wave-number region from the far infrared down to the visible if the cat's-eye retro-reflector comprises a parabolic primary and a spherical secondary.