Chirality is an excellent indicator of life, but naturally occurring terrestrial and extra-terrestrial
samples nearly always exhibit massive depolarizing light scattering (DLS). This problem bears a
striking resemblance to that of developing a chirality-based non-invasive glucose monitor for diabetics.
Both applications require a lightweight, compact, efficient, and robust polarimeter that can operate
despite significant DLS. So for astrobiological applications, we developed a polarimeter that was
inspired from a polarimetry technique previously investigated for non-invasive in-vivo glucose-sensing.
Our polarimeter involves continuously rotating the plane of linear polarization of a laser beam to probe
a sample with DLS, and analyzing its transmission with a fixed analyzer to obtain a sinusoidal voltage
signal. We lock-in detect this signal using a reference signal from an analogous set up without any
sample. With milk as a scatterer, we find that this polarimeter detects chirality in the presence of three
orders of magnitude more DLS than conventional polarimeters. It can accurately measure 0.1° of
polarization rotation in the presence of 15% milk.