Research on Closure Phase Measurement Method of Temporal Domain Interferometric Signal Based on Precise Optical Path Difference Modulation

Closure phase method is one of the important techniques to realize high resolution imaging of long baseline stellar optical interferometry, and obtaining accurate closure phase information is a prerequisite for interferometric image reconstruction. A closure phase measurement method for the temporal domain interferometric signals based on the precise optical path difference modulation is proposed in this paper. The non-redundant precise optical path modulation is carried out on the three-way interferometer arm. With multiple interferometric measurements and data fitting, the sinusoidal error in optical path difference modulation is eliminated, and the optical path modulation accuracy is within 20nm. A high-speed detector is introduced to raise the sampling frequency of the temporal domain interferometric signal, and the temporal domain interferometric signal obtained on the detector is subjected to Fourier transform to obtain the accurate closure phase information of the three-way interferometer arm. The results of laboratory experiments show that the accuracy of the closure phase calculation of the temporal domain signal based on the precise optical path modulation can be improved up to 1/50 wavelength.