Multi-scale photoacoustic microscopy by integrating optical-resolution photoacoustic microscopy and acoustic-resolution photoacoustic microscopy using multi-dimension optical fiber

Abstract

Photoacoustic imaging is a promising technique that combines optical contrast with ultrasonic detection to map the distribution of the absorbing pigments in biological tissues. It has been widely used in biological researches, such as structural imaging of vasculature, brain structural and functional imaging, and tumor detection. Photoacoustic microscopy (PAM) is an important branch of Photoacoustic imaging that can achieve spatial from the micron to submicron level. However, Common photoacoustic microscopy can only be fixed on a single scale (single resolution) for imaging, which makes it difficult to obtain rich information of biological tissue, and cannot adapt to different imaging needs. Here, we developed multi-scale photoacoustic microscopy by integrating optical-resolution photoacoustic microscopy and the acoustic-resolution photoacoustic microscopy using multi-dimension optical fiber. This method mainly uses a single mode fiber and a multimode fiber with same length to split a single laser pulse into two sub-pulses. Finally, the two laser pulses are focused on the sample by the objective lens, which can generate a focal spot covering a few microns to tens of microns near the focal plane. The size of the focal spot is determined by the core diameter of the fiber, and the different size of the spot leads to different lateral resolution, Therefore, the system can achieved both optical resolution (4 μm) and acoustic resolution (40 μm). The multi-scale imaging performance of the system is verified by imaging the blood vessels of mouse and cerebral vascular. The multiscale imaging capability of our system may fulfill different requirements in biomedical researches and facilitate multiscale interpretation in system biology.