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Proceedings Paper

Astrobiological polarimeter
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Paper Abstract

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.

Paper Details

Date Published: 1 October 2007
PDF: 11 pages
Proc. SPIE 6694, Instruments, Methods, and Missions for Astrobiology X, 669419 (1 October 2007); doi: 10.1117/12.736045
Show Author Affiliations
Neeraj Kothari, Georgia Institute of Technology (United States)
Aliakbar Jafarpour, Georgia Institute of Technology (United States)
Tracey L. Thaler, Georgia Institute of Technology (United States)
Rick Trebino, Georgia Institute of Technology (United States)
Andreas S. Bommarius, Georgia Institute of Technology (United States)

Published in SPIE Proceedings Vol. 6694:
Instruments, Methods, and Missions for Astrobiology X
Richard B. Hoover; Gilbert V. Levin; Alexei Y. Rozanov; Paul C. W. Davies, Editor(s)

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