Phasing detection method for the optical multiple-aperture system based on the pyramidal signal

A phasing method for the optical multiple-aperture system can be realized using the overlapping pupils when the light beam is focused onto a pyramid, like a pyramid wavefront sensor. The physical idea of this method is to combine beams from different sub-apertures of the multiple-aperture system to form interference based on focal plane filter of the pyramid. When there is a co-phasing piston error between the sub-apertures, the shape of the interference pattern will change significantly, so that the piston error information can be obtained through this change. Theory analysis and simulation results show that this detection method has good accuracy and linearity. The laboratory experiment based on this method was carried out and the results show that the measurement accuracy of the method is within 10nm. Closed-loop correction of large piston error is also realized by using dual-wavelength technique to resolve the phase ambiguity and the dynamic range can reach several micrometers.