Optical modeling activities for the James Webb Space Telescope (JWST) project: II. Determining image motion and wavefront error over an extended field of view with a segmented optical system

Abstract

This is the second of a series on the optical modeling activities for the JWST government systems engineering integrated modeling team. Starting with the linear optical model discussed in the first installment, we develop centroid and wavefront error sensitivities for the special case of a segmented optical system such as JWST, where the primary mirror consists of 18 individual segments. Our approach extends standard sensitivity matrix methods used for systems consisting of monolithic optics, where the image motion is approximated by averaging ray coordinates at the image and residual wavefront error is determined with global tip/tilt removed. We develop an exact formulation using the linear optical model, and extend it to cover multiple field points for performance prediction at each instrument aboard JWST. This optical model is then driven by thermal and dynamic structural perturbations in an integrated modeling environment. Results are presented.