Daytime optical observation has always been an important application in spatial situational awareness. Research has found that interference detection techniques can effectively suppress the influence of the skylight background and improve the detection capability of dim targets. However, it is intuitively believed that the interference detection system only has a small field of view, which is inconsistent with the experimental results (at least a field of view of 20 °). This article will study the reason why the shearing interference detection system can achieve imaging with a large field of view, provide the theoretical analysis conclusions and the simulation results, and then point out that the field of view of the interference detection system can be greater than 20 °, 97° field of view can form image plane interference.