A survey of infrared polarization in the outdoors

Shaw, Joseph A.

doi:10.1117/12.741897

Cited by 9 publications

(5 citation statements)

References 17 publications

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“…Glints are partially polarized by reflection and become 100% polarized when the reflection angle is very near the Brewster angle (approximately 53°). [12][13][14] This is indicated in the plots of Fig. 7 that show the s-and p-polarized reflectivity on the left and the corresponding degree of polarization 15 on the right for red light reflected from water.…”

Section: Glint Polarization and Blue Glintsmentioning

confidence: 84%

Blue sun reflected from water: optical lessons from observations of nature

Shaw

Vollmer

2017

14th Conference on Education and Training in Optics and Photonics: ETOP 2017

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Specular reflections of the sun from a wind-rippled water surface combine to form a glitter pattern. These reflections are expected to not alter the perceived color of the sun (or other light source), but when the light is reflected near the Brewster angle, the highly polarized glints can appear blue when observed through a polarizer or polarizing sun glasses. This blue appearance is a result of blue light leakage through a standard film polarizer oriented orthogonal to the plane of polarization of the reflected light. Measurements are shown of crossed-polarizer transmission spectra exhibiting blue and near infrared light leakage for photographic polarizing filters and polarized sunglasses. A variety of photographs are shown to confirm blue light leakage as the source of the blue glint color.

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Section: Glint Polarization and Blue Glintsmentioning

confidence: 84%

Blue sun reflected from water: optical lessons from observations of nature

Shaw

Vollmer

2017

14th Conference on Education and Training in Optics and Photonics: ETOP 2017

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“…In long-wave infrared (LWIR) polarimetry the observed polarization signature arises as the net difference between the nominally p-polarized emission and s-polarized reflection of the background [6][7][8][9]. The resulting polarization signature depends on the background in a simpler manner than at shorter wavelengths because the background radiance can be assumed to be unpolarized and to vary primarily with atmospheric water vapor and cloud content [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

“…The resulting polarization signature depends on the background in a simpler manner than at shorter wavelengths because the background radiance can be assumed to be unpolarized and to vary primarily with atmospheric water vapor and cloud content [6][7][8]. The influence of atmospheric radiance on polarization signatures is most significant and variable at visible and near-infrared (Vis-NIR) wavelengths because scattered light (especially Rayleigh scattered light) is quite often partially polarized.…”

Section: Introductionmentioning

confidence: 99%

“…In applications requiring outdoor measurements, it becomes necessary to consider the background radiance generated by atmospheric scattering or emission [6][7][8][9]. The fundamental impact of the atmospheric background on polarimetric imaging of ground-based objects is a change in the polarization signature caused by reflection of the atmospheric radiance.…”

Section: Introductionmentioning

confidence: 99%

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Concurrent polarimetric measurements of painted metal and illuminating skylight compared with a microfacet model

Pust

Shaw

Dahlberg

2009

Polarization Science and Remote Sensing IV

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Previous visible-band laboratory measurements have shown that polarization data can be used to determine optical properties of materials such as the index of refraction with controlled illumination sources. For outdoor measurements, the complex illumination formed by the polarized sky for visible wavelengths makes this process considerably more difficult. This paper reports polarization measurements for horizontal painted-metal and PVC plates and the background atmosphere from a quickly changeable dual-field imaging polarimeter which provides polarization of ground-based objects nearly concurrently with full-sky polarization. A microfacet model has been developed which accounts for the polarized sky illumination and solar-reflecting and flat-reflecting microfacets. Data from this model have been used to explain the primary features of the polarization observed when viewing painted metal and PVC plates outdoors with clear skies. Future work will attempt to use this model with polarimeter data to retrieve the index of refraction of the observed plates.

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“…Aerosols and cloud particles, which are comparable to or larger than the optical wavelength, alter the pure Rayleigh background through scattering processes that do not follow the simple Rayleigh law. Consequently, predicting the polarization pattern observed in the real atmosphere, under conditions other than those leading to pristine Rayleigh scattering, requires careful treatment of the scattering of light by aerosols and cloud particles (Pust and Shaw 2006, 2007, 2009Pust et al , 2009aPust et al , 2009bShaw 2007;Shaw et al 2010). Furthermore, light reflected from the ground mixes with the polarized skylight, generally reducing the net degree of polarization (DoP) observed in the atmosphere .…”

Section: Introductionmentioning

confidence: 99%

Atmospheric Polarization Imaging with Variable Aerosols, Clouds, and Surface Albedo

Shaw¹

2013

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY) 7-15-2013 REPORT TYPE Final Technical Report DATES COVERED (From -To)April 2010 -April 2013 TITLE AND SUBTITLEAtmospheric polarization imaging with variable aerosols, 5a. CONTRACT NUMBER Clouds, and surface albedo. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)Montana State University AND ADDRESS(ES) PERFORMING ORGANIZATION REPORT NUMBEROffice of Sponsored Programs 307 Montana Hall Bozeman, MT 59717-0001 SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S)Air Force Office of Scientific Research 875 N. Randolph St., Rm. 3112 SPONSOR/MONITOR'S REPORTArlington, VA 22203 NUMBER(S) DISTRIBUTION / AVAILABILITY STATEMENT SUPPLEMENTARY NOTES ABSTRACTAn all-sky polarization spectral imager developed under prior support was deployed along with an atmospheric lidar, a sun-tracking multi-channel solar radiometer, and a variety of groundbased aerosol sensors to study the effect of variable aerosols, clouds, and surface reflectance on skylight polarization in the 450 -780 nm spectral region. The entire sensor suite operated continuously from 2009-2012 except for brief periods of maintenance. This study produced a computer model for predicting clear-sky polarization as a function of aerosol properties and surface reflectance, which was validated with measurements and then used to predict clear-sky polarization spectra for various locations around the world. A surface reflectance with a strong wavelength dependence results in lower skylight degree of polarization at wavelengths with higher surface reflectance. Similarly, changing aerosol types and concentrations lead to spatially and temporally variable skylight polarization. SUBJECT TERMS Executive SummaryEffective prediction and exploitation of polarization signatures in optical remote sensing requires improved understanding of the underlying physical mechanisms and phenomenology. To this end we have developed and deployed an all-sky polarization imager, along with a wide range of atmospheric sensors, to study the influence of aerosols and clouds on skylight polarization in the visible and near-infrared spectral band...

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A survey of infrared polarization in the outdoors

Cited by 9 publications

References 17 publications

Blue sun reflected from water: optical lessons from observations of nature

Blue sun reflected from water: optical lessons from observations of nature

Concurrent polarimetric measurements of painted metal and illuminating skylight compared with a microfacet model

Atmospheric Polarization Imaging with Variable Aerosols, Clouds, and Surface Albedo

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