Suchergebnisse

Proceedings of SPIE 9398; San Francisco, California, United States | February 8-9, 2015 ; The goniospectrophotometer GEFE, designed and developed at IO¿CSIC (Instituto de ¿ Optica, Agencia Estatal Consejo Superior de Investigaciones Cient¿¿ficas), was conceived to measure the spectral Bidirectional Reflectance Distribution Function (BRDF) at any pair of irradiation and detection directions. Although the potential of this instrument has largely been proved, it still required to be upgraded to deal with some important scattering features for the assessment of the appearance. Since it was not provided with a detector with spatial resolution, it simply could not measure spectrophotometric quantites to characterize texture through the Bidirectional Texture Function (BTF) or translucency through the more complex Bidirectional Scattering¿Surface Reflectance Distribution Function (BSSRDF). Another requirement in the GEFE upgrading was to provide it with the capability of measuring fluorescence at different geometries, since some of the new pigments used in industry are fluorescent, which can have a non¿negligible impact in the color of the product. Then, spectral resolution at irradiation and detection had to be available in GEFE. This paper describes the upgrading of the goniospectrophotometer GEFE, and its new capabilities through the presentation of sparkle and goniofluorescence measurements. In addition, the potential of the instrument to evaluate translucency by the measurement of the BSSRDF is briefly discussed. ; Authors are grateful to EMRP for funding the project "Multidimensional reflectometry for industry". The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union. Authors are also grateful to Comunidad de Madrid for funding the project SINFOTON-CM: S2013/MIT-2790. ; Peer Reviewed

4 pags., 2 figs. -- Jeju Island of Korea from 16th to 20th of October, 2017 ; In the textile industry, grey scales for colour change are used in fastness tests. These scales consist of nine pairs of neutral grey chips representing a visual colour difference corresponding to fastness ratings from 5 (no contrast) to 1 (highest contrast). The dependence of colour differences on the illumination and viewing directions for two widely-used grey scales ("Grey Scale for Assessing Change in Colour" (SDCE), and "Gray Scale for Evaluating Change in Color" (AATCC)) was evaluated. The spectral bidirectional reflectance distribution function (BRDF) was measured at a set of geometries well distributed in the observation domain, using the goniospectrophotometer GEFE developed at CSIC. It was found that large incidence and viewing angles must be specially avoided using these scales, as providing colour difference values considerably different than those established in ISO 105-A02 and ASTM D2616-96. ; This work was supported by Ministerio de Economía y Competitividad del Gobierno de España, Research Projects FIS2013-40661-P and FIS2016-80983-P, with support from European Regional Development Fund (ERDF), by Comunidad de Madrid (project SINFOTON-CM: S2013/MIT-2790), and by the EMRP IND52 Project "Multidimensional reflectometry for industry" (xD-Reflect). The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union ; Peer Reviewed

10 pags., 8 figs., 3 tabs.-- Open Access funded by Creative Commons Atribution Licence 3.0 ; The assumption that the reflectance of white diffuse reflectance standards is identical to that of the perfect reflecting diffuser (PRD) allows these standards to be used to characterize reflectance or radiance factors of any surface at any irradiation/collection geometry simply by comparison. However, this assumption is only true within certain limits, and, for some applications, requirements may be out of those limits. PTB and IO-CSIC have studied the variation of the reflectance with respect to the bidirectional geometry for the four most typical white diffuse materials (barium sulfate, opal glass, ceramic and Spectralon), at in- A nd out-of plane geometries and at spectral range from 380 nm to 1700 nm. We have defined descriptors in order to more clearly quantify the spectral reflectance variation with the bidirectional geometries. The values obtained for these descriptors have been separately presented for the visible and near-infrared spectral ranges. In both spectral ranges, deviations of white diffuse reflectance standards with respect to the PRD were found, regarding both Lambertian behaviour and spectral constancy. The observed deviation from the BRDF is in general very large for high incidence and collection angles (reaching in many cases 20%). Therefore, it is not possible to assume Lambertianity in standards at those geometries when calibrating measuring systems. ; This article was written within the EMRP IND52 Project xDReflect 'Multidimensional reflectometry for industry'. The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union. Part of the authors (Instituto de Óptica 'Daza de Valdés', CSIC) are also grateful to Comunidad de Madrid for funding the project SINFOTON-CM: S2013/MIT-2790.

8 págs.; 7 figs. ; The spectral bidirectional reflectance distribution function (BRDF) is the key quantity to specify the spectral reflectance of materials for any condition of irradiation and detection, and its characterization is quite important for surfaces with a high dependence on these conditions, such as iridescent coatings. In order to evaluate the calibration and measurement capabilities (CMC) of National Metrology Institutes with the ability to measure the spectral BRDF, a case study interlaboratory comparison is in progress. Spectral BRDF has both spectral and geometric dependence, and this multidimensionality must be treated in the comparison to provide useful information to the participants about their CMCs. A data analysis method for the comparison is presented in this work, which was tested by simulations for different scenarios. The proposed method assesses whether the experimental data from each participant are consistent with those from the others. Finally, one-dimensional and multidimensional degrees of equivalence are defined, which should allow systematic deviations of spectral and geometric nature to be identified. ; This report was compiled within the EMRP IND52 Project xD-Reflect 'Multidimensional reflectometry for industry'. The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union. Part of the authors (Instituto de Óptica 'Daza de Valdés', Agencia Estatal CSIC) are also grateful to Comunidad de Madrid for funding the project SINFOTON-CM: S2013/MIT-2790. ; Peer Reviewed

28th Session, Manchester/UK, June 28 - July 4, 2015; http://session2015.cie.co.at/ ; Fluorescent materials absorb light at a certain wavelength interval and then reemit it at other longer wavelengths, after about 10-8 seconds. Their colour appearance depends upon the combined effect of the fluorescent and reflected radiation. This work is focused in the measurement of the fluorescence of photolumiscent materials as a function of the irradiation and detection directions, which may be called as ¿goniofluorescence¿. It was measured the spectral bidirectional luminiscence distribution function (BLDF) of five fluorescent samples at different combinations of irradiation and detection directions. The measurements were performed with the goniospectrophotometer GEFE, using monochromatic irradiation and a spectrorradiometer as detector. A general behaviour was observed for the five samples and the studied excitation wavelengths: the dependence of the excitation spectrum on the detection direction ¿s is almost symmetrical with respect to ¿s = 0o, decreasing towards high angles. ; This report was compiled within the EMRP IND52 Project xD-Reflect "Multidimensional reflectometry for industry". The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union. Part of the authors (Instituto de Óptica "Daza de Valdés" (IO-CSIC), Agencia Estatal CSIC) are also grateful to the Comunidad de Madrid for funding the project SINFOTON-CM: S2013/MIT-2790. ; Peer Reviewed