Résumé
The need to characterize the mechanical properties of cells led biologists to promote spectroscopy based on Brillouin scattering. This rapidly required a balance between two important criteria: on the one hand, the acquisition time for individual spectra, and on the other, sufficient contrast to observe low-intensity signals. Spectrometers based on VIPA (Virtually imaged phased array) give the possibility of obtaining the full spectrum in just a few hundred milliseconds, with contrasts that make it possible to study biological samples. The addition of a Lyot mask therefore makes it possible, at low cost, to suppress part of the background of the recorded signal, using the geometry of the pattern formed by the two Rayleigh peak suppression slits. This addition, if optimally placed, enables effective transmission to be maintained for Brillouin shift measurement, while gaining 25 dB in contrast. Thus, the configuration presented here, combining a trick for reducing specular reflection at the sample/substrate interface and a device for obtaining measurements under good conditions, makes it possible to envisage combining this spectroscope with other spectroscopy.