Simulations Comparing the Sensitivity of the nlCWFS with the SHWFS

Abstract: We are developing a highly sensitive non-linear Curvature Wavefront Sensor (nlCWFS) which will make it possible to detect objects as dim as mv 14. In this paper we present a WFS sensitivity comparison between the nlCWFS and the SHWFS based on the ability of each WFS to reconstruct a Fourier mode, given a set signal to noise ratio. Theoretical calculations [1] [2] show that the nlCWFS increases the contrast between a host star and an orbiting planet by two orders of magnitudes. We present simulations that substantiate the theory and show that the nlCWFS can detect an object that is at least two visible magnitudes dimmer than is currently possible with the SHWFS. Since the nlCWFS operates in the photon noise limit it does not require the use of a laser guide star (LGS). We have identified two potential optical designs for the nlCWFS. Over the next year a single design will be selected to integrate the nlCWFS with the AFRL/RDS Optics Division 1.5m telescope. 1