Polarization Calibration of the Advanced Technology Solar Telescope

摘要

The Advanced Technology Solar Telescope (ATST) will be the World's largest solar polarimeter with a number of polarimetric instruments simultaneously sharing the ATST light beam. Polarization calibration requires determination of the polarization properties of the telescope optics that are shared by all instruments and the polarization response of each instrument. Hundreds of parameters are required to fully specify the telescope optics but by grouping successive optical elements separated at the Gregorian focus, the elevation rotation, and the Coudé - azimuth rotation and performing calibrations over the course of a day, it is possible to infer the polarization properties of each of the groups, and the instruments themselves with many fewer parameters.