We have previously shown that macroscopic roughness spectra measured with light scattering at visible wavelengths were perfectly extrapolated at high spatial frequencies by microscopic roughness spectra measured with atomic force microscopy [Europhys. Lett. 22, 717 (1993); Proc. SPIE 2253, 614 (1994)]. These results have been confirmed by numerous experiments [Proc. SPIE 2253, 614 (1994)] and allow us today to characterize thin films microstructure from a macroscopic to a microscopic scale. In the first step the comparison of light scattering and atomic force microscopy is completed by optical measurements at UV wavelengths that allow us to superimpose (and no longer extrapolate) the spectra measured by the two techniques. In the second step we extract multiscale parameters that describe the action of thin-film coatings on substrate roughness in all bandwidths. The results obviously depend on materials and substrates and deposition techniques. Electron-beam evaporation, ion-assisted deposition, and ion plating are compared, and the conclusions are discussed in regard to the deposition parameters. Finally, special attention is given to the limits and performances of the two characterization techniques (light scattering and atomic force microscopy) that may be sensitive to different phenomena.
We show how we can measure with accuracy the distribution law of thicknesses deposited inside a vacuum chamber. These measurement techniques are applied to the simultaneous production of high rejection narrowband multiple halfwave Fabry-Perot filters. To prevent any alteration of the filters' optical properties, we must control the variations vs time of the evaporant distribution.
Pour réaliser des multi-démultiplexeurs de hautes performances, on est conduit à employer des filtres Fabry-Pérot multicavités. On montre comment les problèmes de réalisations de ces filtres ont été résolus. C'est en particulier grâce à un contrôle optique direct de la formation de l'empilement que l'on peut garantir un bon accord entre les propriétés optiques attendues et celles effectivement obtenues
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