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Absolute reflectance factor calibration for goniospectrophotometry
Author(s) -
Fairchild Mark D.,
Daoust Denis J. O.,
Peterson Jason,
Berns Roy S.
Publication year - 1990
Publication title -
color research and application
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.393
H-Index - 62
eISSN - 1520-6378
pISSN - 0361-2317
DOI - 10.1002/col.5080150605
Subject(s) - optics , reflectivity , calibration , metrology , diffuse reflectance infrared fourier transform , diffuse reflection , primary standard , materials science , radiation , physics , mathematics , chemistry , statistics , biochemistry , photocatalysis , catalysis
Currently, spectrophotometric standard reference materials are calibrated only using the CIE recommended illumination and viewing geometries. A need exists for standards that have been calibrated at many other combinations of illumination and viewing angles. The common practice has been to assume that a primary transfer standard such as BaSO 4 is Lambertian even though its non‐Lambertian behavior is well documented. This study was undertaken to develop a practical standard for this type of metrology. Two diffuse materials, BaSO 4 and PTFE, were characterized goniospectrophotometrically. Bidirectional absolute spectral reflectance factors were determined for 60 combinations of illumination and view angles in a single plane. Neither material was found to be Lambertian and both failed to completely depolarize reflected radiation. The results were modeled using principal components analysis. The resulting model allows the determination of bidirectional spectral reflectances factors with a minimum effort. PTFE powder can be prepared repeatably with no significant effect on the measured reflectance properties, thus indicating that it would be a suitable primary transfer standard for goniospectrophotometry.