Micro-Brillouin spectroscopy mapping of the residual density field   induced by Vickers indentation in a soda-lime silicate glass
  High-resolution Brillouin scattering is used to achieve 3-dimensional maps of the longitudinal acoustic mode frequency shift in soda-lime silicate glasses subject to Vickers indentations. Assuming that residual stress-induced effects are simply proportional to density changes, residual densification fields are obtained. The density gradient is nearly isotropic, confirming earlier optical observations made on a similar glass. The results show that Brillouin micro-spectroscopy opens the way to a fully quantitative comparison of experimental data with predictions of mechanical models for the identification of a constitutive law. 
H. Tran, S. Cl\'ement, R. Vialla, D. Vandembroucq, and B. Ruffl\'e
cond-mat.mtrl-sci cond-mat.dis-nn