Performance comparison of high-speed photoacoustic microscopy: opto-ultrasound combiner versus ring-shaped ultrasound transducer.

Photoacoustic microscopy (PAM) embedded with a 532 nm pulse laser is widely used to visualize the microvascular structures in both small animals and humans in vivo. An opto-ultrasound combiner (OUC) is often utilized in high-speed PAM to confocally align the optical and acoustic beams to improve the system's sensitivity. However, acoustic impedance mismatch in the OUC results in little improvement in the sensitivity.

Characterization of a 40-MHz focused transducer with a fiber grating laser hydrophone.

A novel fiber-optic hydrophone based on a dual-polarization, short-cavity fiber grating laser as the sensing element is described. Wet chemical etching was used to fabricate a thinned fiber sensor to extend its frequency response as well as spatial resolution. The lateral beam profile at the focal plane of a 40-MHz lens-focused lithium niobate (LiNbO) transducer was measured with the fiber sensor, and a tomographic technique was used to compute the transducer profile, which is compared with that obtained by a PVDF hydrophone.