Time-reversed adapted-perturbation (TRAP) optical focusing onto dynamic objects inside scattering media


The ability to steer and focus light inside scattering media has long been sought for a multitude of applications. At present, the only feasible strategy to form optical foci inside scattering media is to guide photons by using either implanted1 or virtual2,3,4 guide stars, which can be inconvenient and limits the potential applications. Here we report a scheme for focusing light inside scattering media by employing intrinsic dynamics as guide stars. By adaptively time-reversing the perturbed component of the scattered light, we show that it is possible to focus light to the origin of the perturbation. Using this approach, we demonstrate non-invasive dynamic light focusing onto moving targets and imaging of a time-variant object obscured by highly scattering media. Anticipated applications include imaging and photoablation of angiogenic vessels in tumours, as well as other biomedical uses.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Principle and schematic of TRAP focusing.
Figure 2: Dynamic light focusing onto a moving target hidden inside a scattering medium.
Figure 3: Focusing light onto flowing targets inside biological tissue.
Figure 4: Imaging a hidden time-variant object.


  1. 1

    Vellekoop, I. M., van Putten, E. G., Lagendijk, A. & Mosk, A. P. Demixing light paths inside disordered metamaterials. Opt. Express 16, 67–80 (2008).

    ADS  Article  Google Scholar 

  2. 2

    Xu, X., Liu, H. & Wang, L. V. Time-reversed ultrasonically encoded optical focusing into scattering media. Nature Photon. 5, 154–157 (2011).

    ADS  Article  Google Scholar 

  3. 3

    Si, K., Fiolka, R. & Cui, M. Fluorescence imaging beyond the ballistic regime by ultrasound-pulse-guided digital phase conjugation. Nature Photon. 6, 657–661 (2012).

    ADS  Article  Google Scholar 

  4. 4

    Wang, Y. M., Judkewitz, B., DiMarzio, C. A. & Yang, C. Deep-tissue focal fluorescence imaging with digitally time-reversed ultrasound-encoded light. Nature Commun. 3, 928 (2012).

    ADS  Article  Google Scholar 

  5. 5

    Ntziachristos, V. Going deeper than microscopy: the optical imaging frontier in biology. Nature Methods 7, 603–614 (2010).

    Article  Google Scholar 

  6. 6

    Vellekoop, I. M. & Mosk, A. P. Focusing coherent light through opaque strongly scattering media. Opt. Lett. 32, 2309–2311 (2007).

    ADS  Article  Google Scholar 

  7. 7

    Katz, O., Small, E., Bromberg, Y. & Silberberg, Y. Focusing and compression of ultrashort pulses through scattering media. Nature Photon. 5, 372–377 (2011).

    ADS  Article  Google Scholar 

  8. 8

    Popoff, S., Lerosey, G., Fink, M., Boccara, A. C. & Gigan, S. Image transmission through an opaque material. Nature Commun. 1, 81 (2010).

    ADS  Article  Google Scholar 

  9. 9

    Chaigne, T. et al. Controlling light in scattering media non-invasively using the photoacoustic transmission matrix. Nature Photon. 8, 58–64 (2014).

    ADS  Article  Google Scholar 

  10. 10

    Tay, J. W., Lai, P., Suzuki, Y. & Wang, L. V. Ultrasonically encoded wavefront shaping for focusing into random media. Sci. Rep. 4, 3918 (2014).

    ADS  Article  Google Scholar 

  11. 11

    Yaqoob, Z., Psaltis, D., Feld, M. S. & Yang, C. Optical phase conjugation for turbidity suppression in biological samples. Nature Photon. 2, 110–115 (2008).

    ADS  Article  Google Scholar 

  12. 12

    Hsieh, C-L., Pu, Y., Grange, R., Laporte, G. & Psaltis, D. Imaging through turbid layers by scanning the phase conjugated second harmonic radiation from a nanoparticle. Opt. Express 18, 20723–20731 (2010).

    ADS  Article  Google Scholar 

  13. 13

    Vellekoop, I. M., Cui, M. & Changhuei, Y. Digital optical phase conjugation of fluorescence in turbid tissue. Appl. Phys. Lett. 101, 081108 (2012).

    ADS  Article  Google Scholar 

  14. 14

    Judkewitz, B., Wang, Y. M., Horstmeyer, R., Mathy, A. & Yang, C. Speckle-scale focusing in the diffusive regime with time reversal of variance-encoded light (TROVE). Nature Photon. 7, 300–305 (2013).

    ADS  Article  Google Scholar 

  15. 15

    Wang, L. V. & Hu, S. Photoacoustic tomography: in vivo imaging from organelles to organs. Science 335, 1458–1462 (2012).

    ADS  Article  Google Scholar 

  16. 16

    Briers, D. et al. Laser speckle contrast imaging: theoretical and practical limitations. J. Biomed. Opt. 18, 066018 (2013).

    ADS  Article  Google Scholar 

  17. 17

    Bertolotti, J. et al. Non-invasive imaging through opaque scattering layers. Nature 491, 232–234 (2012).

    ADS  Article  Google Scholar 

  18. 18

    Yang, X., Pu, Y. & Psaltis, D. Imaging blood cells through scattering biological tissue using speckle scanning microscopy. Opt. Express 22, 3405–3413 (2014).

    ADS  Article  Google Scholar 

  19. 19

    Fienup, J. R. Reconstruction of an object from the modulus of its Fourier transform. Opt. Lett. 3, 27–29 (1978).

    ADS  Article  Google Scholar 

  20. 20

    Anderson, D. Z., Feinberg, J. & Lininger, D. M. Optical tracking novelty filter. Opt. Lett. 12, 123–125 (1987).

    ADS  Article  Google Scholar 

  21. 21

    Cudney, R., Pierce, R. & Feinberg, J. The transient detection microscope. Nature 332, 424–426 (1988).

    ADS  Article  Google Scholar 

  22. 22

    Brooks, R. E., Heflinger, L. O. & Wuerker, R. F. Pulsed laser holograms. IEEE J. Quantum Electron. 2, 275–279 (1966).

    ADS  Article  Google Scholar 

  23. 23

    Liu, R., Qin, J. & Wang, R. K. Motion-contrast laser speckle imaging of microcirculation within tissue beds in vivo. J. Biomed. Opt. 18, 060508 (2013).

    ADS  Article  Google Scholar 

  24. 24

    Miccio, L. et al. Particle tracking by full-field complex wavefront subtraction in digital holography microscopy. Lab Chip 14, 1129–1134 (2014).

    Article  Google Scholar 

  25. 25

    Fouda, A. E. & Teixeira, F. L. Imaging and tracking of targets in clutter using differential time reversal techniques. Wave Random Complex 22, 66–108 (2012).

    ADS  Article  Google Scholar 

  26. 26

    Brady, D. J. et al. Multiscale gigapixel photography. Nature 486, 386–389 (2012).

    ADS  Article  Google Scholar 

  27. 27

    Jin, Y., Jia, C., Huang, S-W., O'Donnell, M. & Gao, X. Multifunctional nanoparticles as coupled contrast agents. Nature Commun. 1, 41 (2010).

    ADS  Article  Google Scholar 

  28. 28

    Peterka, D. S., Takahashi, H. & Yuste, R. Imaging voltage in neurons. Neuron 69, 9–21 (2011).

    Article  Google Scholar 

  29. 29

    Rust, M. J., Bates, M. & Zhuang, X. Sub-diffraction-limit imaging by stochastic optical reconstruction microscopy (STORM). Nature Methods 3, 793–796 (2006).

    Article  Google Scholar 

  30. 30

    Patterson, G. H. & Lippincott-Schwartz, J. A Photoactivatable GFP for selective photolabeling of proteins and cells. Science 297, 1873–1877 (2002).

    ADS  Article  Google Scholar 

Download references


We thank F. Zhou for assistance on the flow-control system, L. Wang for discussion on the experimental design, Y. Zhou for assistance on the dye-solution preparation and J. Ballard for editing the manuscript. This work was supported by the National Institutes of Health grants DP1 EB016986 (NIH Director's Pioneer Award) and R01 CA186567 (NIH Director's Transformative Research Award).

Author information




C.M. and L.V.W. initiated the project. C.M. and X.X. implemented the DOPC-based system. C.M., X.X. and Y.L. designed and ran the experiments. C.M. wrote the codes for the experiments and simulation, and processed the experimental results. L.V.W. provided overall supervision. All authors were involved in writing the manuscript.

Corresponding author

Correspondence to Lihong V. Wang.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary information

Supplementary information (PDF 2063 kb)

Supplementary Movie 1

Supplementary Movie 1 (MOV 5633 kb)

Supplementary Movie 2

Supplementary Movie 2 (MOV 501 kb)

Supplementary Movie 3

Supplementary Movie 3 (MOV 681 kb)

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Ma, C., Xu, X., Liu, Y. et al. Time-reversed adapted-perturbation (TRAP) optical focusing onto dynamic objects inside scattering media. Nature Photon 8, 931–936 (2014). https://doi.org/10.1038/nphoton.2014.251

Download citation

Further reading


Sign up for the Nature Briefing newsletter for a daily update on COVID-19 science.
Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing