title: Exploring a photo-acousto-optic effect for noncontacting photoacoustic sensing.
abstract: To avoid the use of ultrasound transducers and coupling gel in photoacoustic microscopy (PAM), we propose photo-acousto-optic tomography (PAOT) for noncontact photoacoustic (PA) sensing. The process consists of two parts. The first portion is the same as typical PAM, which employs a pulsed laser to induce acoustic waves. The difference from typical methods lies in the second part of the process, which applies a DC beam, rather than a conventional transducer, to sense the PA signal. A two-beam optical microscope system was designed to verify the PAOT effect, whereby an AC spot acted as the source to induce a PA signal, while a DC beam is applied to induce the acousto-optic effect for detection of the acoustic wave. We demonstrated the preliminary result that 5-100 Hz AC radiation could derive PA waves in a water-like medium along with detection sensitivity as high as 4.9%-10.0%; besides, the signal waveform could be detected by a DC spot 10-100 μm away for noncontact sensing with detection sensitivity of about 3.7%-10.4%. Without the need for a transducer or coupling gel, PAOT has the potential to modify conventional PAM into a pure optical system, which could make PA imaging more promising in practical applications.
authors.forename: Bor-Wen
authors.initials: BW
authors.lastname: Yang
authors.forename: Hong-You
authors.initials: HY
authors.lastname: Chen
authors.forename: Yu-Siang
authors.initials: YS
authors.lastname: Huang
authors.forename: Hong-Wei
authors.initials: HW
authors.lastname: Chen
authors.forename: Hing-Yang
authors.initials: HY
authors.lastname: Yu
authors.forename: D C
authors.initials: DC
authors.lastname: Yeh