Polarization analysis of Fizeau-type Y-4 prototype

Optical synthesis aperture telescope technology can be used to get more rich astronomical information. Interference fringe scanning method is commonly used to eliminate optical path difference between different optical delayed lines, but due to the polarization difference between the interference arms will lead to interference fringe contrast degradation especially in interference type instrument. Especially when observing faint, more distant targets, it is more necessary to consider the polarization effects caused by the instrument itself. In this paper, the Fizeau-type Y-4 prototype developing by Shanghai Astronomical Observatory, Chinese Academy of Sciences is introduced first of all. Based on the principle of the vector-wave superposition, this paper focuses on fringe contrast degradation caused by polarization effects and the changes of polarization states caused by coating of different material. The simulation results show that the interference fringe contrast is sensitive to the polarization effects. Similarly, the changes of polarization state of the beam caused by the coating needs to be considered when designing the optical interferometer. Finally, a polarization compensator is proposed to compensate the polarization difference.