Scanning mirror-based photoacoustic microscopy with synthetic aperture focusing technique

In photoacoustic microscopy (PAM), the lateral resolution degrades significantly in out-of-focus region of a focused transducer. Synthetic aperture focusing technique (SAFT) combined with coherence factor is an effective method to improve the lateral resolution in out-of-focus region. In this work, we proposed and demonstrated mirror scanning instead of commonly employed linear scanning using a translation stage to obtain cross-sectional image. The scanning mirror reflects the photoacoustic signal, which is then detected by a stationary transducer. A large aperture for SAFT can be synthesized by summing properly delayed photoacoustic signals reflected by the mirror scanned at different angles. Hair-thread phantoms were used to validate the feasibility of the proposed method for simple and fast data acquisition in PAM with SAFT.