Imaging with Scattered Light

Random scattering of light in complex samples such as biological tissue renders most objects opaque to optical imaging techniques. However, although random, scattering is a deterministic process, and it can be undone, and also exploited by controlling the incident optical wavefront. These insights form the basis for the emerging field of optical wavefront-shaping [1]. Opening the path to new possibilities, such as imaging through visually opaque samples and around corners [2].

However, two major challenges exist in the field today: the first is how to determine the required wavefront correction without accessing the far (target) side of the scattering sample. The second is how to do it faster than the dynamics of the sample.

I will present some of our recent efforts in addressing these challenges [3-11]. These include the guidance of wavefront-shaping using non-linear effects [3], the photoacoustic effect [4-6], and acousto-optics [7-8]. In addition I will show how one can exploit the dynamics of the samples instead of fighting them. I will also demonstrate how it is possible to image through scattering layers and ‘around corners’ using nothing but a smartphone camera [9], using correlations of scattered light.

If time permits, I will present the use of these principles for endoscopic imaging through optical fibers [10-11].

REFERENCES

[1] A.P. Mosk et al., "Controlling waves in space and time for imaging and focusing in complex media", Nature Photonics 6, 283 (2012).

[2] O. Katz et al., "Looking around corners and through thin turbid layers in real time with scattered incoherent light", Nature Photonics 6, 549 (2012).

[3] O.Katz et al., "Noninvasive nonlinear focusing and imaging through strongly scattering turbid layers", Optica, 1, 3, 170-174 (2014).

[4] T. Chaigne et al. "Controlling light in scattering media noninvasively using the photo-acoustic transmission-matrix.", Nature Photonics 8, 58 (2014).

[5] E.Hojman et al. "Photoacoustic imaging beyond the acoustic diffraction-limit with dynamic speckle illumination and sparse joint support recovery", Optics Express Vol. 25, Issue 5, pp. 4875-4886 (2017)

[6] T. Chaigne et al. "Super-resolution photoacoustic imaging via flow-induced absorption fluctuations", Optica Vol. 4, Issue 11, pp. 1397-1404 (2017)

[7] O. Katz et al. " Controlling light in complex media beyond the acoustic diffraction-limit using the acousto-optic transmission matrix", Nature Communications (2019)

[8] D. Doktofsky et al. “Acousto-optic tomography beyond the acoustic diffraction-limit using speckle decorrelation”, arXiv: 1812.00400.

[9] O. Katz et al., "Non-invasive single-shot imaging through scattering layers and around corners via speckle correlations", Nature Photonics, 8, 784–790 (2014)

[10] A.Porat et al., "Widefield lensless imaging through a fiber bundle via speckle-correlations", Optics Express (2016)

[11] U.Weiss et al., “Two-photon lensless micro-endoscopy with in-situ wavefront correction” Optics Express Vol. 26, Issue 22, pp. 28808-28817 (2018).