Photoacoustic tomography has been developed for in vivo functional, metabolic, molecular, and histologic imaging by physically combining optical and ultrasonic waves. Conventional high-resolution optical imaging of scattering tissue is limited to depths within the optical diffusion. Taking advantage of the fact that ultrasonic scattering is orders of magnitude weaker than optical scattering per unit path length, photoacoustic tomography beats this limit and provides deep penetration at high ultrasonic resolution and high optical contrast.

Wavefront engineering overcomes the optical diffusion limit by actively controlling the wavefront of the incident light to optimize the light intensity at a target position inside tissue. Time-reversed ultrasonically encoded (TRUE) optical focusing can noninvasively deliver light to a dynamically defined focus deep in a scattering medium. First, diffused coherent light is encoded by a focused ultrasonic wave to provide a virtual internal “guide star”; then, only the encoded light is time-reversed and transmitted back to the ultrasonic focus.

Compressed ultrafast photography (CUP) can image in 2D non-repetitive time-evolving events at up to 100 billion frames per second. CUP has a prominent advantage of measuring an x, y, t scene with a single camera snapshot, thereby allowing observation of transient events occurring on a time scale down to tens of picoseconds. Further, akin to traditional photography, CUP is receive-only—avoiding specialized active illumination required by other single-shot ultrafast imagers.

 

 Lihong Wang earned his Ph.D. degree at Rice University, Houston, Texas. His book entitled “Biomedical Optics: Principles and Imaging,” won the 2010 Joseph W. Goodman Book Writing Award. He has published 450 peer-reviewed articles in journals and delivered 440 keynote, plenary, or invited talks. His Google Scholar h-index and citations have reached 108 and 46,000, respectively.

He is the Editor-in-Chief of the Journal of Biomedical Optics. He received the NIH’s FIRST, NSF’s CAREER, NIH Director’s Pioneer, and NIH Director’s Transformative Research awards. He also received the OSA C.E.K. Mees Medal, IEEE Technical Achievement Award, IEEE Biomedical Engineering Award and SPIE Britton Chance Biomedical Optics Award.