On Stokes polarimeters for high precision CMB measurements and mm Astronomy measurements

摘要

Several on-going and future experiments use a Stokes polarimeter (i.e. arotating wave plate followed by a steady polarizer and by an unpolarizeddetector) to measure the small polarized component of the Cosmic MicrowaveBackground. The expected signal is typically evaluated using the Muellerformalism. In this work we carry-out the signal evaluation taking into accountthe temperatures of the different optical devices present in the instrument,their non- idealities, multiple internal reflections, and reflections betweendifferent optical components. This analysis, which exploits a new descriptionof the radiation transmitted by a half wave plate, can be used to optimize theexperimental setup as well as each of its optical components. We conclude withan example of application of our analysis, studying a cryogenic polarizationmodulator developed for detecting the interstellar dust polarization.