Procedures and standards that have been developed at the National Research Council of Canada for the accurate measurement of specular reflectance are discussed for both absolute and relative methods over the spectral range 250 to 2500 nm. There has been an increasing demand for these types of measurements, particularly for coated samples approaching the extremes of 0% reflectance and 100% reflectance. In some applications of these coatings, such as energy conservation and control, conventional methods of measuring specular reflectance give insufficient accuracies for the prediction of optical performance. Details of alignment procedures for both absolute and relative reflectance methods, the preparation and application of several candidate reflectance standards, and the compensation, attenuation, and verification procedures that have been developed to improve the precision and accuracy of specular reflectance measurements are described. Using these various techniques, one can routinely achieve accuracies of 0.3% reflectance at reflectance values as high as 97% and as low as 4%.

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Screen printable inks for Ta2O5 and TiO2 antireflection coatings have been applied to silicon wafers and characterized. On polished crystalline wafers, both coatings give near-zero minimum reflectance. The wavelength of the minimum can be easily tuned to match the solar spectrum by changing the screen mesh size. The average reflectance over the AM1 spectrum can be further reduced by texturizing the wafer surface prior to coating. Similar reflectance results are obtained for both crystalline and polycrystalline wafers, although the average reflectance is not quite as low in the latter case due to the difficulty of texturizing polycrystalline material.

Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n'arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. Questions?Contact the NRC Publications Archive team at PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information. NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. NRC Publications Record / Notice d'Archives des publications de CNRC:http://nparc.nrc-cnrc.gc.ca/eng/view/object/?id=b3ca3df4-59d0-401f-b2f4-b73579662b2d http://nparc.nrc-cnrc.gc.ca/fra/voir/objet/?id=b3ca3df4-59d0-401f-b2f4-b73579662b2dOptical properties of UV transmitting acrylics for use in a heavy water Cerenkov detector Joanne C. Zwinkels, W. F. Davidson, and C. X. DoddThe absorption, refraction, and scattering properties of several UV transmitting acrylics have been investigated over the wavelength range 300-700 nm using a combination of near-normal incidence regular transmittance and reflectance and diffuse-only reflectance measurements, followed by a Fresnel and a Kubelka-Munk analysis. The samples were evaluated in the as-cast and thermoformed forms, and both before and after an accelerated aging procedure. The results show significant differences in the optical behavior of the various acrylics in the UV region and stress the importance of carefully characterizing acrylic from different sources for each intended use. In our case, acrylic is the proposed material for a heavy water containment vessel for the detection of solar neutrinos. The significance of our findings to the overall performance of this Cerenkov detector, known as the Sudbury neutrino observatory detector, is discussed.

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