title: Optical focusing inside scattering media with time-reversed ultrasound microbubble encoded light.
abstract: Focusing light inside scattering media in a freely addressable fashion is challenging, as the wavefront of the scattered light is highly disordered. Recently developed ultrasound-guided wavefront shaping methods are addressing this challenge, albeit with relatively low modulation efficiency and resolution limitations. In this paper, we present a new technique, time-reversed ultrasound microbubble encoded (TRUME) optical focusing, which can focus light with improved efficiency and sub-ultrasound wavelength resolution. This method ultrasonically destroys microbubbles, and measures the wavefront change to compute and render a suitable time-reversed wavefront solution for focusing. We demonstrate that the TRUME technique can create an optical focus at the site of bubble destruction with a size of ∼2 μm. We further demonstrate a twofold enhancement in addressable focus resolution in a microbubble aggregate target by exploiting the nonlinear pressure-to-destruction response of the microbubbles. The reported technique provides a deep tissue-focusing solution with high efficiency, resolution, and specificity.
authors.affiliation: Department of Electrical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, USA.
authors.forename: Haowen
authors.initials: H
authors.lastname: Ruan
authors.affiliation: Department of Electrical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, USA.
authors.forename: Mooseok
authors.initials: M
authors.lastname: Jang
authors.affiliation: Department of Electrical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, USA.
authors.forename: Changhuei
authors.initials: C
authors.lastname: Yang
mesh_terms: D003287:Contrast Media; D008027:Light; D045423:Microbubbles; D012542:Scattering, Radiation; D014463:Ultrasonography
chemical_list: D003287:Contrast Media