Formation thermique de facettes sur les monocristaux de cuivre en relation avec l'anisotropie de la tension superficielle

Doctorat en Sciencesinfo:eu-repo/semantics/nonPublishe

Mesure de l'épaisseur de films minces métalliques à l'aide de franges d'interférence d'égal ordre chromatique

The authors have measured thicknesses of silver thin films by using fringes of equal chromatic order : these were of low order (n varying from 3 to 30) and the effect of phase shift has been examined for low n especially. Interpreting the results shows the global shift Φ = Φ(λ) appearing in the interferometer as a linear function of λ ; the accuracy of the measurement is discussed and the authors also describe a method for obtaining accurate measurements of thickness.Les auteurs ont mesuré des épaisseurs de lames minces d'argent en utilisant des franges d'égal ordre chromatique. Ils ont réalisé ces mesures à l'aide de franges d'ordre bas (n variant de 3 à 30) et ont étudié l'effet des déphasages qui se manifestent surtout pour n petit. De l'interprétation des résultats, il apparaît qu'en première approximation le déphasage global Φ = Φ(λ) se produisant dans l'interféromètre est une fonction linéaire de λ; la précision des mesures est discutée et ils décrivent une méthode pour obtenir des mesures dépaisseur précises

Incremental ring core by optical methods: preliminary results

The ring core method is a well-known technique for residual stress measuring. It consists of milling a circular ring around the point of interest and measuring the surface deformations of the core. The method is more sensitive than hole drilling, but its sensitivity decreases with depth to become null when ring depth is equal to one third of the diameter. To overcome this problem, in literature an incremental version of the technique has been proposed consisting of removing the core, re- installing the strain gauge rosette and re-performing the measurement. Although the idea is interesting, its practical implementation is quite difficult, in particular re-installing the rosette is almost impossible when depth becomes significant, thus the incremental measurement is never performed. In this work we propose to replace the strain gauge rosette with an optical technique. In this way the incremental approach becomes viable, even though, depending on the optical technique used, some practical problems have to be addressed