Optical full-field holographic detection system for non-contact photoacoustic tomography

We introduce an innovative detection approach for photoacoustic tomography. The pressure induced surface displacement is obtained in 2D by Electronic Speckle Pattern Interferometry (ESPI) in a repetitive measurement with a variable time delay between excitation- and detection pulses. The detection approach works without any physical contact to the object surface and is very versatile in terms of an adjustable object surface area and an adjustable temporal sampling rate. Furthermore, the approach is potentially very fast by the use of a high speed camera and a high repetition laser excitation and detection. In a proof of concept measurement, transparent silicone cubes with black silicone sphere absorbers are measured. In order to validate the acquired displacement data, the pressure is measured using a lipstick needle hydrophone and correlated to the measured displacement.