High-speed label-free ultraviolet photoacoustic microscopy for histology-like imaging of unprocessed biological tissues.

Ultraviolet photoacoustic microscopy (UV-PAM) has recently been demonstrated as a potential imaging tool for surgical margin analysis (SMA). UV-PAM does not require staining or micrometer-thick slicing, which is inevitable in conventional histological imaging. To promote UV-PAM as a practical intraoperative diagnostic tool, the imaging speed should be improved while preserving the high-resolution imaging capability and simplistic system design. In this Letter, we developed a galvanometer mirror-based UV-PAM (GM-UV-PAM) system for high-speed histology-like imaging. By using a UV laser with a high repetition rate (55 kHz) and a one-dimensional galvanometer mirror, our GM-UV-PAM system can generate subcellular images in less than 15 min for a typical brain biopsy (5mm×5mm), with a lateral resolution of ∼1.0µm. The images of mouse brain slices obtained by our GM-UV-PAM system show that it can provide histological information for SMA.