Synergy of light and sound for deep-tissue optical imaging and focusing

Abstract

Light and sound are the two most dominant mechanisms with which we naturally perceive this world. Both have their significant impacts yet with inherent limitations. For example, sound is insensitive to soft tissue functional changes, and light is strongly scattered in tissue, resulting in a trade-off between penetration depth and resolution. Here, we present our most recent research efforts of exploiting the synergy of light and sound to overcome this limitation. Specifically, photoacoustics converts diffusive photon into non-scattering ultrasonic waves, enabling a high-contrast sensing of optical absorption with ultrasonic resolution in deep tissue, overcoming the optical diffusion limit from the signal detection perspective. The generation of photoacoustic signals, however, is still throttled by the attenuation of photon flux due to the strong diffusion effect of light in tissue. Therefore, wavefront shaping is introduced, so that multiply scattered light could be manipulated so as to retain optical focusing or sufficient photon flux even at depths in tissue. We will present the recent development of photoacoustic imaging and optical wavefront shaping in our lab. Potential applications, existing challenges, and further improvement are also discussed.Light and sound are the two most dominant mechanisms with which we naturally perceive this world. Both have their significant impacts yet with inherent limitations. For example, sound is insensitive to soft tissue functional changes, and light is strongly scattered in tissue, resulting in a trade-off between penetration depth and resolution. Here, we present our most recent research efforts of exploiting the synergy of light and sound to overcome this limitation. Specifically, photoacoustics converts diffusive photon into non-scattering ultrasonic waves, enabling a high-contrast sensing of optical absorption with ultrasonic resolution in deep tissue, overcoming the optical diffusion limit from the signal detection perspective. The generation of photoacoustic signals, however, is still throttled by the attenuation of photon flux due to the strong diffusion effect of light in tissue. Therefore, wavefront shaping is introduced, so that multiply scattered light could be manipulated so as to retain optical foc...