Research on the new detection method of suppressing the skylight background based on the shearing interference and...

In order to effectively suppress the effect of the skylight background on the detection performance of the optical telescope and make it have the advantages of the all-time operation and the high star-magnitude detection, a new detection method based on the shearing interference and the phase modulation is proposed in this paper. This method utilizes the discrepancy of the spatial coherence between the target (smaller size) and the skylight background (larger size). By adjusting the shearing amount reasonably, the target light can form the interference fringes, while the skylight background cannot. Then, the phase modulation technique is used to form the moving interference fringes over the detector. Afterward, the periodical electrical signal is formed by the photoelectrical conversion of the detector. Finally, the weak signal detection equipment can be used to extract the target signal from the skylight background noise. This paper introduces the scheme design and the theoretical analysis of the new detection method and also presents the detection performance simulation of this new method.