Design considerations of rotary interference spectral imager(ROSI)

The rotary interference spectral imager (ROSI) is based on the Sagnac lateral shifted interferometer. The optical path pifference (OPD) is obtained by rotating one of the two mirrors of the Sagnac interferometer. It is an instrument with the merits of high sensitivity, high stability and staring imaging, etc. Some calculation aspects including the principle parameters of the system, the relation between the OPD and the structure parameters of the interferometer, the relation between the OPD and the rotary angle of the mirror, the rotating speed and sampling frequency of ROSI are presented. The mismatch problem between the rotating speed and detector sampling frequency is discussed and solved by oversampling method.