Focus-tunable fiber-laser ultrasound sensor for high-resolution linear-scanning photoacoustic computed tomography

In this study, we presented a high-resolution linear-scanning photoacoustic computed tomography (PACT) system with a focus-tunable fiber-laser ultrasound sensor. By bending the fiber laser into a curvature radius of 25 mm, an 85 μm × 150 μm in-plane resolution and a 300 μm elevational resolution were achieved. The elevational resolution was ∼3 times better than the previously reported value. Hair phantoms at multiple depths from 2 cm to 6 cm were clearly observed by tuning the bending curvature. Additionally, the fiber-laser-based PACT system showed its capability for high-resolution imaging of small animals based on the images of abdominal subcutaneous vasculatures from a rat. With the excitation light delivered by a fiber bundle and the ultrasound detected by a fiber laser, this all-fiber linear-scanning PACT system holds great potential for photoacoustic imaging in preclinical and clinical applications.