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Proceedings Paper

Polarizing interference coatings made with anisotropic thin films
Author(s): Francois Flory; Celine Defay
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Paper Abstract

It is now well known that the microstructure of materials in thin film form can be slightly different from that of corresponding bulk materials. Conventional evaporation using a heated crucible or an electron beam gun generally leads to a lacunar structure in columns. Some consequences of this microstructure on the optical properties of the films are well-known. The refractive indices are slightly smaller than that of the bulk material; water adsorption-desorption in the voids leads to variations of the spectral reflection and transmission of the coatings. But apart from these disadvantages, the columnar structure can present advantages because it also induces anisotropy of refractive index. When deposited with an ion beam assistance the microstructure of the material is modify and so is its anisotropy. The anisotropy can then be controlled through the ion energy, making it possible to construct multilayer filters combining both isotropic films and anisotropic films. This opens the way for the making of components acting on the polarization state of light. Results of calculation for different components are presented. Planar non absorbing monochromatic polarizers or polarization rotators can be made in this way. The difficulty in controlling the deposition comes from the fact that the anisotropic layers must be deposited on non rotating substrates. This problem is discussed and examples of measured optical properties of multilayer filters will be given.

Paper Details

Date Published: 2 July 1998
PDF: 8 pages
Proc. SPIE 3405, ROMOPTO '97: Fifth Conference on Optics, (2 July 1998); doi: 10.1117/12.312722
Show Author Affiliations
Francois Flory, Ecole Nationale Superieure de Physiqe de Marseille (France)
Celine Defay, Ecole Nationale Superieure de Physiqe de Marseille (France)

Published in SPIE Proceedings Vol. 3405:
ROMOPTO '97: Fifth Conference on Optics
Valentin I. Vlad; Dan C. Dumitras, Editor(s)

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