Parallelism error analysis and its effect on modulation depth based on a rotating parallel mirror Fourier spectrometer.

The stability of the moving mirror of a Michelson Fourier transform spectrometer (M-FTS) has a non-negligible influence on its spectral quality, which limits its application. We proposed a spectrometer scheme with a pair of rotating parallel mirrors (RPM-FTS), which has advantages of fast response and high stability. The influence of the parallelism error of parallel mirrors on interference was analyzed by establishing a rotation vector model between the parallelism error, rotation angle, and optical path. The modulation depth of the RPM-FTS is more insensitive with the same installation error of the M-FTS; thus, more spectral details can be displayed easily.