Time-domain Brillouin imaging of sound velocity and refractive index using automated angle scanning.

We present a picosecond optoacoustic technique for mapping both the longitudinal sound velocity and the refractive index in solids by automated measurement at multiple probe incidence angles in time-domain Brillouin scattering. Using a fused silica sample with a deposited titanium film as an optoacoustic transducer, we map and in the depth direction. Applications include the imaging of sound velocity and refractive index distributions in three dimensions in inhomogeneous samples such as biological cells.