Grüneisen-relaxation photoacoustic microscopy at 1.7 µm and its application in lipid imaging
Jiawei Shi, Can Li, Huade Mao, Yu‐Xuan Ren, Zhi‐Chao Luo, Amir Rosenthal, Kenneth K. Y. Wong
Abstract
We report the first, to the best of our knowledge, demonstration of Grüneisen relaxation photoacoustic microscopy (GR-PAM) of lipid-rich tissue imaging at the 1.7 µm band, implemented with a high-energy thulium-doped fiber laser and a fiber-based delay line. GR-PAM enhances the image contrast by intensifying the region of strong absorbers and suppressing out-of-focus signals. Using GR-PAM to image swine-adipose tissue at 1725 nm, an 8.26-fold contrast enhancement is achieved in comparison to conventional PAM. GR-PAM at the 1.7 µm band is expected to be a useful tool for label-free high-resolution imaging of lipid-rich tissue, such as atherosclerotic plaque and nerves.