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Proceedings Paper

Investigation of photoluminescent effect in opal glasses used as diffuse reflectance standards
Author(s): Joanne C. Zwinkels; Francois Gauthier
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Paper Abstract

Lack of photoluminescence is an essential requirement of a reference standard that is used to calibrate color-measuring instruments. This effect is being studied for several white reflecting materials commonly used as diffuse reflectance standards. This paper reports on the findings for two types of Russian opal (MS20 and MS14) and Japanese opal (Everwhite) glasses. Russian opal glass is under consideration by ASTM Committee E12.12 on Appearance of Metallics and Pearlescents as a transfer standard for the calibration of goniospectrocolorimeters and Japanese opal has been used for many years as a transfer standard in paper colorimetry. The accurate characterization of photoluminescence in these opal glasses is important in determining their suitability for these applications. These measurements were performed on the NRC Reference Spectrofluorimeter over the wavelength range 250-800 nm. It was found that the photoluminescent effect was weakest in the Russian opal glass MS14 and strongest in the Japanese opal. Both types of Russian opal glass exhibit a single broad emission band from 320-450 nm (max=370nm) which is excited by UV radiation from <250-320 nm (max=280 nm), excited by UV radiation in the ranges <250-280 nm (max<250 nm) and 250-340 nm (max=310 nm), respectively. The former emission band is responsible for a bright-blue fluorescent color when the sample is irradiated with short-wave UV (254 nm). The impact of this photoluminescent effect was quantified by calculation of the resultant colorimetric errors in the CIE chromaticity coordinates, luminance value, and CIE whiteness for two common illumination conditions: filtered xenon which approximates CIE Illumination D65 and unfiltered xenon which approximates an equi-energy source. For the former case, the colorimetric errors were negligible for both types of Russian opal glass and only significant for the Japanese opal for the whiteness value (0.12% error). For the equi-energy source, the errors in chromaticities ranged from 0.0003 to 0.0007, in luminance value from 0.07 to 0.16, and in CIE Whiteness value from 0.80 to 2.0. Recommendations are given regarding the use of these opal glasses as transfer standards for reflection colorimetry.

Paper Details

Date Published: 8 August 2003
PDF: 9 pages
Proc. SPIE 4826, Fourth Oxford Conference on Spectroscopy, (8 August 2003); doi: 10.1117/12.514521
Show Author Affiliations
Joanne C. Zwinkels, National Research Council (Canada)
Francois Gauthier, National Research Council (Canada)

Published in SPIE Proceedings Vol. 4826:
Fourth Oxford Conference on Spectroscopy
Art Springsteen; Michael Pointer, Editor(s)

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