A first order wavefront estimation algorithm for P1640 calibrator

摘要

P1640 calibrator is a wavefront sensor working with the P1640 coronagraph and the Palomar 3000 actuatoradaptive optics system (P3K) at the Palomar 200 inch Hale telescope. It measures the wavefront by interferingpost-coronagraph light with a reference beam formed by low-pass filtering the blocked light from the coronagraphfocal plane mask. The P1640 instrument has a similar architecture to the Gemini Planet Imager (GPI) and itsperformance is currently limited by the quasi-static speckles due to non-common path wavefront errors, whichcomes from the non-common path for the light to arrive at the AO wavefront sensor and the coronagraph mask.By measuring the wavefront after the coronagraph mask, the non-common path wavefront error can be estimatedand corrected by feeding back the error signal to the deformable mirror (DM) of the P3K AO system. Here, wepresent a first order wavefront estimation algorithm and an instrument calibration scheme used in experimentsdone recently at Palomar observatory. We calibrate the P1640 calibrator by measuring its responses to pokingDM actuators with a sparse checkerboard pattern at different amplitudes. The calibration yields a complexnormalization factor for wavefront estimation and establishes the registration of the DM actuators at the pupilcamera of the P1640 calibrator, necessary for wavefront correction. Improvement of imaging quality after feedingback the wavefront correction to the AO system demonstrated the efficacy of the algorithm.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.