Space-time coherence of fixed delay michelson interferometer

The resolution of middle resolution spectrometer can be improved several times by fixed delay Michelson interferometer. So it is on a good place to survey radial velocity. But this kind of interferometer needs some analysis about its space-time coherence, because of some restricting factors, i.e. large field angle and wide wave band. Its field compensation and space-time coherence were analyzed by deriving its OPD formula, comparing it with traditional Michelson interferometer and modeling it. The results indicate that fixed delay Michelson interferometer has an excellent performance on space-time coherence under the condition of fully compensating the field difference and connecting to spectrometer.