arXiv subjects

Cheng Ma

Publications and source records attributed to Cheng Ma.

39 records · Page 3Linked to original sources

arXiv2015

Fast binarized time-reversed adapted-perturbation (b-TRAP) optical focusing inside scattering media

Light scattering inhibits high-resolution optical imaging, manipulation and therapy deep inside biological tissue by preventing focusing. To form deep foci, wavefront-shaping and time-reversal techniques that break the optical diffusion limit have been developed. For in vivo applications, such focusing must provide high gain, high speed, and a large number of spatial modes. However, none of the previous techniques meet these requirements simultaneously. Here, we overcome this challenge by rapidly measuring the perturbed optical field within a single camera exposure followed by adaptively time-reversing the phase-binarized perturbation. Consequently, a phase-conjugated wavefront is synthesized within a millisecond, two orders of magnitude shorter than the digitally achieved record. We demonstrated real-time focusing in dynamic scattering media, and extended laser speckle contrast imaging to new depths. The unprecedented combination of fast response, high gain, and large mode count makes this work a major stride toward in vivo deep tissue optical imaging, manipulation, and therapy.

physics.optics↗

arXiv2015

Novel solid-state glycine-nitrate combustion for controllable synthesis of hierarchically porous Ni monolith

We demonstrate a novel solid-state glycine-nitrate route for not only the scalable combustion synthesis of hierarchically porous Ni monolith, but also control over impurities, microstructure topography and size. The as-synthesized porous Ni monolith may find instant applications as electrode current collectors, catalyst and catalyst substrates or sensors.

cond-mat.mtrl-sci↗

arXiv2014

Tracking and imaging of dynamic objects in scattering media by time-reversed adapted-perturbation (TRAP) optical focusing

The ability to steer light propagation inside scattering media has long been sought-after due to its potential widespread applications. To form optical foci inside scattering media, the only feasible strategy is to guide photons by using either implanted or virtual guide stars. However, all of these guide stars must be introduced extrinsically, either invasively or by physical contact, limiting the scope of their application. Here, we focus light inside scattering media by employing intrinsic dynamics as guide stars. By time-reversing the perturbed component of the scattered light adaptively, we concentrate light to the origin of the perturbation, where the permittivity varied spontaneously. We demonstrate dynamic light focusing onto moving targets and imaging of a time-variant object obscured by highly scattering media, without invasiveness and physical contact. Anticipated applications include all-weather optical communication with airplanes or satellites, tracking vehicles in thick fogs, and imaging and photoablation of angiogenic vessels in tumors.

physics.optics↗