Abstract:
Earth is the only known habitable planet and it serves as a testbed to benchmark the
observations of temperate and more Earth-like exoplanets. It is required to observe the diskintegrated signatures of Earth for a large range of phase angles, resembling the observations
of an exoplanet. In this work, an acousto-optic tunable filter (AOTF)-based experiment is
designed to observe the spectro-polarimetric signatures of Earth. The results of spectroscopic
and polarimetric laboratory calibration are presented here along with a brief overview of a
possible instrument configuration. Based on the results of the spectro-polarimetric calibration,
simulations are carried out to optimize the instrument design for the expected signal levels for
various observing conditions. The usefulness of an AOTF-based spectro-polarimeter is established from this study, and it is found that, in the present configuration, the instrument can
achieve a polarimetric accuracy of <0.3% for linear polarization for an integration time of
100 ms or larger. The design configuration of the instrument and the planning of conducting
such observations from Lunar orbit are discussed. © 2022 Society of Photo-Optical Instrumentation
Engineers (SPIE) [DOI: 10.1117/1.JATIS.8.4.044007]
