Performance of segmented mirror coarse phasing with a dispersed fringe sensor: modeling and simulations

Dispersed Fringe Sensing (DFS) is an efficient and robust method for coarse phasing of a segmented primary mirror such as the James Webb Space Telescope (JWST). Results from testbed experiments and modeling have shown that among the many factors that affect the performance of DFS, the diffraction from segment aperture and the interference between the segment wavefronts have the most intrinsic influence on the DFS performance. In this paper, modeling and simulations based on diffraction are used to study the formation of DFS fringe and fringe properties such as visibility. We examine the DFS piston detection process and explore the limitation of DFS wavefront piston detection accuracy and the DFS dynamic range under different segment aperture geometries, aperture orientations, and image samplings.