Photoacoustic eigen-spectrum from light-absorbing microspheres and its application in noncontact elasticity evaluation Available to Purchase

Noncontact evaluation of elastic properties of a microstructure is still a challenge in turbid media. In this Letter, we present the observation of a phenomenon—the photoacoustic eigen-spectrum from light-absorbing objects. Analysis and experiments demonstrate that the eigen-vibration information of a microstructure is imprinted in its photoacoustic coda waves after it is exposed to a laser pulse illumination. The spectral lines in the time-frequency map of photoacoustic coda waves correspond to the eigen-frequencies of the light-absorber. This phenomenon provides a physical basis for noncontact evaluation of elastic properties of a microstructure in turbid media. Elastic parameters can be accurately inversed from the measured photoacoustic eigen-spectrum.