Demodulation method of orthogonal interferometer based on 1/8 wave plate

摘要

The orthogonal interferometer based on 1/8 wave plate generates orthogonal signals by optical configuration. It is widely applied to interference system because of simple optical path and passive demodulation scheme for easy operation. But in the process of demodulation, the DC component of the signal needs to be eliminated. Because of the instability of light source and optical structure, the DC component of the signal may change over time. Therefore the circuit subtracting a constant can not thoroughly eliminate the DC component, causing the demodulation results are inaccurate. A improved demodulation algorithm is proposed in this paper. Theoretical analysis and experimental results show that, the demodulation method is almost not affected by the size of the DC component. When small deviation in DC component occurs, the demodulation results keep stable and accurate.