Control of amplitude errors in the Project 1640 cronagraph

Eric Cady (JPL)

The Project 1640 instrument at the Hale Telescope at Palomar
Observatory is one of the first of a new generation of planet-finding
coronagraphs coupled to high-order wavefront control systems.  In
addition to the 3388-actuator PALM-3000 system, the coronagraph also
uses an interferometric calibrator to measure the complex field and
correct slowly-varying phase errors during an observation.  One of the
remaining factors to limit performance is the presence of amplitude
errors, which are uncorrected by phase conjugation techniques; I will
discuss our progress toward implementation of simultaneous phase and
amplitude correction on the instrument, and our plans to improve
performance for the future.