Label-free in vivo fiber-based optical-resolution photoacoustic microscopy.

In this Letter, the capability of label-free fiber-based optical-resolution photoacoustic microscopy is demonstrated. This real-time imaging system takes advantage of image-guide fibers and a unique fiber laser. The 800 μm image-guide consists of 30,000 individual single-mode fibers in a bundle and the diode-pumped, pulsed Ytterbium fiber laser is utilized to perform up to 600 kHz repetition rate. Phantom studies indicate 7 μm resolution. The proposed setup keeps many of the powerful properties of previous tabletop OR-PAM systems, but also offers a submillimeter probe footprint and high flexibility due to the nature of the image-guide. This system could have significant clinical impact for endoscopic applications where the thin fiber can be inserted into the body.