Abstract
Principles and experimentation of Brillouin scattering spectroscopy for the study of biological samples.Among the many properties of biological samples, the mechanical characteristics were not extensively studied. For several decades, Brillouin spectroscopy based on Fabry-Perot cavity tandems has helped to measure these biomechanical properties, based on the interaction between light and acoustic phonons. Thanks to their high contrast, these set-ups still offer major advantages today, particularly for mineralized, highly absorbing or scattering materials. The appearance of a solid standard, the VIPA (virtually imaged phased array), has given rise to a multitude of experimental set-ups enabling rapid measurement of Brillouin spectra, but with lower contrast performance.Using two VIPAs in series, combined with a mask based on Lyot coronography, it was possible to achieve 80 dB with a spectrograph that was highly stable over time. This was coupled with a confocal microscope. By using a MgF2 substrate with an optical index close to that of water, specular reflection at the aqueous medium/substrate interface was greatly reduced, enabling individual cells to be mapped with optical resolution, in a timeframe compatible with sample preservation. In parallel, the mapping of highly mineralized samples, such as the dental organ, requires instruments with higher contrast, such as Sandercock-type mounts based on Fabry-Perot tandems, albeit with very long acquisition times.These results encourage us to pursue both experiments in line with biologists' expectations, and improvements in versatile measuring instruments, with times compatible with sample preservation.