High-Sensitivity Optical-Resolution Photoacoustic Microscopy with an Optical-Acoustic Combiner Based on an Off-Axis Parabolic Acoustic Mirror

Optical-resolution photoacoustic microscopy (OR-PAM) is a promising noninvasive biomedical imaging technology with label-free optical absorption contrasts. Performance of OR-PAM is usually closely related to the optical-acoustic combiner. In this study, we propose an optical-acoustic combiner based on a flat acoustic reflector and an off-axis parabolic acoustic mirror with a conical bore. Quantitative simulation and experiments demonstrated that this combiner can provide better acoustic focusing performance and detection sensitivity. Moreover, OR-PAM is based on the combiner suffer low optical disorders, which guarantees the good resolution. In vivo experiments of the mouse brain and the iris were also conducted to show the practicability of the combiner in biomedicine. This proposed optical-acoustic combiner realizes a high-quality optical-acoustic confocal alignment with minimal optical disorders and acoustic insertion loss, strong acoustic focusing, and easy implementation. These characteristics might be useful for improving the performance of OR-PAM.