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The Project 1640 instrument on the 200-inch Hale telescope at PalomarObservatory is a coronagraphic instrument with an integral field spectrographat the back end, designed to find young, self-luminous planets around nearbystars. To reach the necessary contrast for this, the PALM-3000 adaptive opticssystem corrects for fast atmospheric speckles, while CAL, a phase-shiftinginterferometer in a Mach-Zehnder configuration, measures the quasistaticcomponents of the complex electric field in the pupil plane following thecoronagraphic stop. Two additional sensors measure and control low-order modes.These field measurements may then be combined with a system model and datataken separately using a white-light source internal to the AO system tocorrect for both phase and amplitude aberrations. Here, we discuss anddemonstrate the procedure to maintain a half-plane dark hole in the image planewhile the spectrograph is taking data, including initial on-sky performance.

Electric Field Conjugation with the Project 1640 coronagraph