Abstract

Photoacoustic remote sensing microscopy is a recently developed optical non-contact imaging method that provides optical absorption contrast in reflection mode. Previously, this was performed by co-scanning of tightly co-focused excitation and interrogation beams. We have demonstrated the proof of principle that superficial optical absorption information can be measured from a scattering sample by a camera in reflection mode using a pulsed excitation and interrogation beams. This allows wide field-of-view absorption imaging in scattering samples in real-time. Using a wire-bonding wire embedded in a phantom, the photoacoustic effect is first induced by a 532-nm pulsed excitation beam which alters the optical property of the wire that is illuminated with a 1064-nm pulsed interrogation beam with 80 ns delay. The scattering of the interrogation beam with and without the excitation beam is captured by the camera and the difference is calculated. Increasing contrast in difference images can be observed as the fluence rate of the excitation beam is set to 5.28 mJ/cm², 12.8 mJ/cm², 19.5 mJ/cm² and 26.0 mJ/cm². The mean relative difference is increased from 0.92 %, 2.10 %, 2.64 % and 3.27%, respectively.

© 2019 SPIE/OSA