Imaging of live 3T3 cells with phonons.
(a) Optical image of the scanned area. (b) Brillouin shift measured from (a) sampling every 1 μm, taking ~1.5 s per point and a total of 38 minutes total acquisition time. (c) Section obtained at d = 1 μm. (d) Section obtained at d = ~1.8 μm. As sound propagates, thin filopodia (marked by white circle, square) are resolved axially as the section moves deeper into the cell.