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Please use this identifier to cite or link to this item: http://hdl.handle.net/2014/41082

Title: Use of photoelastic modulators for high-accuracy spectropolarimetric imaging of aerosols
Authors: Diner, David J.
Davis, Ab
Cunningham, Tom
Gutt, Gary
Hancock, Bruce
Raouf, Nasrat
Wang, Yu
Zan, Jason
Chipman, Russell
Beaudry, Neil
Hirschy, Linda
Keywords: Multi-angle Imaging SpectroRadiometer (MISR)
photoelastics
aerosols
Issue Date: 26-Jun-2006
Publisher: Pasadena, CA : Jet Propulsion Laboratory, National Aeronautics and Space Administration, 2006.
Citation: 2006 Earth Science Technology Conference (ESTC-06), College Park, MD, June 26, 2006.
Abstract: Passive multiangular, multispectral, and polarimetric sensing approaches each have unique strengths for the measurement of tropospheric aerosol column abundances and microphysical properties. Current spaceborne multispectral and multiangular aerosols sensors operate at ~1 km resolution. Under NASA’s Instrument Incubator Program, we are developing an electro-optic imaging approach that will enable adding high-accuracy polarimetry to such observations. To achieve a degree of linear polarization (DOLP) uncertainty of 0.5%, our approach temporally modulates the linear-polarization component of incoming light at a rapid rate, enabling each detector within a focal-plane array, combined with polarization analyzers, to measure the relative proportions of the linear Stokes components Q or U to the total intensity. Our system uses tandem photoelastic modulators (PEMs) within a high-reflectance, low diattenuation camera design. The two PEMs vibrate at slightly different resonant frequencies, leading to modulation of the polarized light at a heterodyne frequency of ~25 Hz. High-speed (1 kHz) readout of the detector arrays samples the output waveforms from which Q/I and U/I are derived. We report on experimental and theoretical analyses of PEM and optical system performance, along with plans for developing ruggedized PEMs capable of withstanding launch and on-orbit stresses.
URI: http://hdl.handle.net/2014/41082
Appears in Collections:JPL TRS 1992+

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