Abstract: A method for marking references on a flat article includes providing a model having at least a through-opening and exhibiting the same peripheral profile as a flat article to be marked; detecting the peripheral profile of the model and storing that profile in a memory; detecting a profile of the through-opening and the relative positioning with respect to a reference system; detecting a peripheral profile of the flat article; replicating the peripheral profile of the model so as to superpose it on the peripheral profile of the flat article; replicating also the profile of the through-opening of the detected model, taking account of the relative positioning with respect to the reference system and of the positioning of the peripheral profile of the model with respect to the peripheral profile of the flat article. Contactless marking of at least a reference on the flat article is made at the profile of the through-opening which has been replicated.

Abstract: A method for marking references on a flat article includes providing a model having at least a through-opening and exhibiting the same peripheral profile as a flat article to be marked; detecting the peripheral profile of the model and storing that profile in a memory; detecting a profile of the through-opening and the relative positioning with respect to a reference system; detecting a peripheral profile of the flat article; replicating the peripheral profile of the model so as to superpose it on the peripheral profile of the flat article; replicating also the profile of the through-opening of the detected model, taking account of the relative positioning with respect to the reference system and of the positioning of the peripheral profile of the model with respect to the peripheral profile of the flat article. Contactless marking of at least a reference on the flat article is made at the profile of the through-opening which has been replicated.

Abstract: A method for measuring the refractive index of a material with Bragg gratings includes the emission of a collimated radiation beam (9) from a radiation source (4) with a large spectrum and orientation thereof along a direction normal to the material (2) to be examined, the propagation of the collimated radiation beam (9) entering the material (2), then a Bragg diffraction grating (3) that is obliquely placed to the direction of the collimated radiation beam (9), and again the material (2), the subjection to spectral analysis of the collimated radiation beam exiting the material (2), the grating (3) producing a minimum in the spectrum subjected to the spectral analysis in accordance with Bragg's law, and the calculation of the refractive index of the material (2) from the measure of the wavelength corresponding to the minimum in thus spectrum. A relevant apparatus is described.

Abstract: A method for measuring the refractive index of a material with Bragg gratings includes the emission of a collimated radiation beam (9) from a radiation source (4) with a large spectrum and orientation thereof along a direction normal to the material (2) to be examined, the propagation of the collimated radiation beam (9) entering the material (2), then a Bragg diffraction grating (3) that is obliquely placed to the direction of the collimated radiation beam (9), and again the material (2), the subjection to spectral analysis of the collimated radiation beam exiting the material (2), the grating (3) producing a minimum in the spectrum subjected to the spectral analysis in accordance with Bragg's law, and the calculation of the refractive index of the material (2) from the measure of the wavelength corresponding to the minimum in thus spectrum. A relevant apparatus is described.