Abstract

The Johns Hopkins University (JHU) is continuing its development of an Adaptive Optics Coronagraph (AOC) to include a wavefront curvature sensor (WCS) of the type described by Roddier¹ and a membrane mirror for full correction of the distorted wavefront. Initially constructed with an image motion compensation system for the removal of wavefront tilt effects,² the fully-adaptive AOC will retain the high speed tip/tilt mirror of the earlier instrument to complement the membrane mirror in the feedback loop. The complete system is shown schematically in Figure 1. The 91 element membrane mirror (M1) is placed in the recollimated telescope beam at the location of the telescope exit pupil, and corrects for all wavefront aberrations other than tilt. The tip/tilt mirror (M2) removes image motion due to wavefront tilt, and the light is then refocussed by lens L2 onto the occulting mask (M3). This mask, consisting of a small aluminum spot deposited on a clear window, reflects the light of the bright star into the WCS leg of the instrument, while the circumstellar environment is imaged, aberration free, in the coronagraph leg.

© 1992 Optical Society of America