Design of the life signature detection polarimeter LSDpol

Christoph U. Keller, Frans Snik, C. H.Lucas Patty, Dora Klindzic, Mariya Krasteva, David S. Doelman, Thomas Wijnen, Vidhya Pallichadath, Daphne M. Stam, More Authors

Research output: Chapter in Book/Conference proceedings/Edited volumeConference contributionScientificpeer-review

5 Citations (Scopus)
25 Downloads (Pure)


Many biologically produced chiral molecules such as amino acids and sugars show a preference for left or right handedness (homochirality). Light reflected by biological materials such as algae and leaves therefore exhibits a small amount of circular polarization that strongly depends on wavelength. Our Life Signature Detection polarimeter (LSDpol) is optimized to measure these signatures of life. LSDpol is a compact spectropolarimeter concept with no moving parts that instantaneously measures linear and circular polarization averaged over the field of view with a sensitivity of better than 10-4. We expect to launch the instrument into orbit after validating its performance on the ground and from aircraft. LSDpol is based on a spatially varying quarter-wave retarder that is implemented with a patterned liquid-crystal. It is the first optical element to maximize the polarimetric sensitivity. Since this pattern as well as the entrance slit of the spectrograph have to be imaged onto the detector, the slit serves as the aperture, and an internal field stop limits the field of view. The retarder's fast axis angle varies linearly along one spatial dimension. A fixed quarter-wave retarder combined with a polarization grating act as the disperser and the polarizing beam-splitter. Circular and linear polarization are thereby encoded at incompatible modulation frequencies across the spectrum, which minimizes the potential cross-talk from linear into circular polarization.

Original languageEnglish
Title of host publicationSpace Telescopes and Instrumentation 2020
Subtitle of host publicationOptical, Infrared, and Millimeter Wave
EditorsMakenzie Lystrup, Marshall D. Perrin
ISBN (Electronic)9781510636736
Publication statusPublished - 2020
EventSpace Telescopes and Instrumentation 2020: Optical, Infrared, and Millimeter Wave - Virtual, Online, United States
Duration: 14 Dec 202022 Dec 2020

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceSpace Telescopes and Instrumentation 2020: Optical, Infrared, and Millimeter Wave
Country/TerritoryUnited States
CityVirtual, Online


  • Biosignatures
  • Circular polarization
  • Earth
  • Exoplanets
  • Homochirality
  • Polarimetry
  • Spectropolarimetry


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