A Caltech Library Service

Focusing on moving targets through scattering samples

Zhou, Edward Haojiang and Ruan, Haowen and Yang, Changhuei and Judkewitz, Benjamin (2014) Focusing on moving targets through scattering samples. Optica, 1 (4). pp. 227-232. ISSN 2334-2536. PMCID PMC4301445. doi:10.1364/OPTICA.1.000227.

[img] PDF - Published Version
See Usage Policy.

[img] Video (QuickTime) - Supplemental Material
See Usage Policy.

[img] PDF - Supplemental Material
See Usage Policy.


Use this Persistent URL to link to this item:


Focusing light through scattering media has been a longstanding goal of biomedical optics. While wavefront shaping and optical time-reversal techniques can in principle be used to focus light across scattering media, achieving this within a scattering medium with a noninvasive and efficient reference beacon, or guide star, remains an important challenge. Here, we show optical time-reversal focusing using a new technique termed Time Reversal by Analysis of Changing wavefronts from Kinetic targets (TRACK). By taking the difference between time-varying scattering fields caused by a moving object and applying optical time reversal, light can be focused back to the location previously occupied by the object. We demonstrate this approach with discretely moved objects as well as with particles in an aqueous flow, and obtain a focal peak-to-background strength of 204 in our demonstration experiments. We further demonstrate that the generated focus can be used to noninvasively count particles in a flow-cytometry configuration—even when the particles are hidden behind a strong diffuser. By achieving optical time reversal and focusing noninvasively without any external guide stars, using just the intrinsic characteristics of the sample, this work paves the way to a range of scattering media imaging applications, including underwater and atmospheric focusing as well as noninvasive in vivo flow cytometry.

Item Type:Article
Related URLs:
URLURL TypeDescription CentralArticle
Zhou, Edward Haojiang0000-0001-7020-9502
Ruan, Haowen0000-0002-4917-4509
Yang, Changhuei0000-0001-8791-0354
Judkewitz, Benjamin0000-0002-8570-3869
Additional Information:© 2014 Optical Society of America. Received 21 July 2014; revised 12 August 2014; accepted 23 August 2014 (Doc. ID 217492); published 1 October 2014. Funding: GIST-Caltech (CG2012); NIH (1DP2OD007307-01); Wellcome Trust (WT092197). We thank Roarke Horstmeyer and Chen Xu for carefully reading our manuscript and providing helpful advice. B. J. was supported by a Sir Henry Wellcome postdoctoral fellowship.
Funding AgencyGrant Number
GIST-Caltech Research CollaborationCG2012
Wellcome TrustWT092197
Issue or Number:4
PubMed Central ID:PMC4301445
Record Number:CaltechAUTHORS:20150427-132705735
Persistent URL:
Official Citation:E. Zhou, H. Ruan, C. Yang, and B. Judkewitz, "Focusing on moving targets through scattering samples," Optica 1, 227-232 (2014)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:57018
Deposited By: Tony Diaz
Deposited On:27 Apr 2015 21:02
Last Modified:10 Nov 2021 21:06

Repository Staff Only: item control page