Boundary diffraction wave integrals for diffraction modeling of external occulters

摘要

An occulter is a large diffracting screen which may be flown in conjunctionwith a telescope to image extrasolar planets. The edge is shaped to minimizethe diffracted light in a region beyond the occulter, and a telescope may beplaced in this dark shadow to view an extrasolar system with the starlightremoved. Errors in position, orientation, and shape of the occulter willdiffract additional light into this region, and a challenge of modeling anocculter system is to accurately and quickly model these effects. We present afast method for the calculation of electric fields following an occulter, basedon the concept of the boundary diffraction wave: the 2D structure of theocculter is reduced to a 1D edge integral which directly incorporates theocculter shape, and which can be easily adjusted to include changes in occulterposition and shape, as well as the effects of sources---such asexoplanets---which arrive off-axis to the occulter. The structure of a typicalimplementation of the algorithm is included.