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Proceedings Paper

A spectroscopic polarimeter for detecting chiral signatures in astrobiological samples
Author(s): Baoliang Wang; William B. Sparks; Thomas A. Germer; Andrew Leadbetter
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Paper Abstract

We have developed a polarimeter for accurately measuring both the circular and linear polarization components of a light beam from 400 nm to 800 nm. This polarimeter is designed to work at low light levels that are typical in astronomical applications. It is optimized to detect the circular polarization signal that is orders of magnitude weaker than the linear polarization signal. Two photoelastic modulators (PEMs) are the key polarization components employed in this polarimeter to afford the high sensitivity required for the application. Using this instrument, we have quantified the circular polarization signal produced by astrobiologically relevant microorganisms and compared the results to macroscopic vegetation (such as leaves) and abiotic minerals. Our aim is to understand whether circular polarization offers a viable technique for remote detection of chiral signatures and hence will be useful as an element of telescopic searches for life elsewhere in the Universe. We see unambiguous circular polarization from photosynthetic microbes. The circular polarization of reflected light is related to the circular dichroism of photosynthetic molecules. Therefore, circular polarization spectroscopy offers the prospect of remotely sensing life's unique chiral signature.

Paper Details

Date Published: 3 September 2009
PDF: 11 pages
Proc. SPIE 7441, Instruments and Methods for Astrobiology and Planetary Missions XII, 744108 (3 September 2009); doi: 10.1117/12.826378
Show Author Affiliations
Baoliang Wang, Hinds Instruments, Inc. (United States)
William B. Sparks, Space Telescope Science Institute (United States)
Thomas A. Germer, National Institute of Standards and Technology (United States)
Andrew Leadbetter, Hinds Instruments, Inc. (United States)

Published in SPIE Proceedings Vol. 7441:
Instruments and Methods for Astrobiology and Planetary Missions XII
Kurt D. Retherford; Richard B. Hoover; Gilbert V. Levin; Alexei Yu. Rozanov, Editor(s)

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