Low uncertainty measurements of bidirectional reflectance factor on the NPOESS/VIIRS solar diffuser

Kristen Lessel, Stephen McClain

Research output: Chapter in Book/Report/Conference proceedingConference contribution

13 Scopus citations


An illuminated Solar Diffuser is the calibration source for the VIS/NIR bands on the NPOESS/VIIRS sensor. We completed a set of BRF measurements to fully characterize the distribution of scattered light from the solar diffuser. NPOESS/VIIRS has an overall VIS/NIR radiometric calibration uncertainty requirement of 2%(1 sigma), of which 1.32% was allocated to the characterization of the BRF. In order to meet this requirement, we modified the existing goniometer and measurement procedure used on MODIS. Modifications include sample yoke redesign, periodic measurements of the lamp polarization coupled with stability measurements, modifications to source optics, and stray light reduction. We measured BRF in 6 spectral wavebands for 9 out-of-plane illumination angles and 2 view angles. We achieved NIST traceable measurements with an uncertainty ranging from 1.09% to 1.32%. Our measurements of a smaller Spectralon™ sample match NIST measurements of the same sample to better than 0.5%. These requirements are nominally the same as achieved on MODIS. As a result of instrument upgrades, we currently meet this overall uncertainty while having included additional uncertainty terms.

Original languageEnglish (US)
Title of host publicationEarth Observing Systems XII
StatePublished - 2007
Externally publishedYes
EventEarth Observing Systems XII - San Diego, CA, United States
Duration: Aug 26 2007Aug 28 2007

Publication series

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


OtherEarth Observing Systems XII
Country/TerritoryUnited States
CitySan Diego, CA

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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