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jasonSWIR Calibration of Spectralon Reflectance FactorSatellite instruments operating in the reflective solar wavelength region require accurate and precise determination of the Bidirectional Reflectance Factor (BRF) of laboratory-based diffusers used in their pre-flight and on-orbit radiometric calibrations. BRF measurements are required throughout the reflected-solar spectrum from the ultraviolet through the shortwave infrared. Spectralon diffusers are commonly used as a reflectance standard for bidirectional and hemispherical geometries. The Diffuser Calibration Laboratory (DCaL) at NASA's Goddard Space Flight Center is a secondary calibration facility with reflectance measurements traceable to those made by the Spectral Tri-function Automated Reference Reflectometer (STARR) facility at the National Institute of Standards and Technology (NIST). For more than two decades, the DCaL has provided numerous NASA projects with BRF data in the ultraviolet (UV), visible (VIS) and the Near infraRed (NIR) spectral regions. Presented in this paper are measurements of BRF from 1475nm to 1625nm obtained using an indium gallium arsenide detector and a tunable coherent light source. The sample was a 2 inch diameter, 99% white Spectralon target. The BRF results are discussed and compared to empirically generated data from a model based on NIST certified values of 6deg directional/hemispherical spectral reflectance factors from 900nm to 2500nm. Employing a new NIST capability for measuring bidirectional reflectance using a cooled, extended InGaAs detector, BRF calibration measurements of the same sample were also made using NIST's STARR from 1475nm to 1625nm at an incident angle of 0deg and at viewing angles of 40deg, 45deg, and 50deg. The total combined uncertainty for BRF in this ShortWave Infrared (SWIR) range is less than 1%. This measurement capability will evolve into a BRF calibration service in SWIR region in support of NASA remote sensing missions. Keywords: BRF, BRDF, Calibration, Spectralon, Reflectance, Remote Sensing.
Document ID
20110020822
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Georgiev, Georgi T. (Sigma Space, Inc. Lanham, MD, United States)
Butler, James J. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Cooksey, Cahterine (National Inst. of Standards and Technology Gaithersburg, MD, United States)
Ding, Leibo (Sigma Space, Inc. Lanham, MD, United States)
Thome, Kurtis J. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 25, 2013
Publication Date
September 19, 2011
Subject Category
Optics
Report/Patent Number
GSFC.ABS.5292.2011
Meeting Information
Meeting: SPIE Remote Sensing 2011
Location: Prague
Country: Czech Republic
Start Date: September 19, 2011
End Date: October 2, 2011
Sponsors: International Society for Optical Engineering
Distribution Limits
Public
Copyright
Public Use Permitted.

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