Suppression of DWS-based angular errors via refined Gaussian interferometric models in space gravitational wave detection

Differential Wavefront Sensing (DWS) is sensitive to laser intensity inhomogeneity, leading to measurement errors and parasitic tilting. Therefore, a high-precision numerical model has been developed to elucidate the mechanisms of comprehensive error sources for DWS. Simulation results identify lateral offset as the dominant error source. To mitigate this effect, we implement post-processing subtraction to elevate the angular accuracy to 98.4%. Subsequently, an enhanced analytical model explicitly linking lateral offset to DWS with two Gaussian beams interference is derived for the first time. Based on error sources contributions, our designed heterodyne interferometer error margins below 6.3 μrad within the angular range of ±500 μrad. Experimental results demonstrate that accuracy levels of 98% and 89% are attained by the improved numerical model and enhanced analytical model, respectively. Compared to previous Gaussian-Gaussian interference approaches, our refined models offer superior precision, especially for extended measurement ranges. The results clearly confirm the effectiveness and practicality of the proposed methods. Those approaches provide valuable insights for DWS measurement systems and space gravitational wave detection.