Acoustic pressure wave trajectory tracking using structured light

Photo-acoustic imaging is a burgeoning field of research, that can be a powerful tool for imaging in liquids, materials and biological samples. Effective methods for high-speed and spatial resolved opto-acoustic sensing could help transform the field of photo-acoustic imaging. We propose a novel measurement strategy leveraging the optical beams that carry Orbital Angular Momentum (OAM) to create a high-speed, spatially sensitive acoustic field detector. We measure the relative power difference between selected modes from the output of a passive optical OAM mode-sorter, to monitor trajectory of acoustic pulses in room temperature water. Our investigation revealed that relative power between odd-valued OAM superpositions are effective for measuring acoustic wave trajectory, where increased OAM value provided an increased measurement sensitivity. We will present theoretical results that showcase the extension of this technique for complex spatial profiling and will discuss a road map for the utilization of this technique for photo-acoustic imaging.