Looking around corners and through thin turbid layers in real time with scattered incoherent light

Katz, Ori; Small, Eran; Silberberg, Yaron

doi:10.1038/nphoton.2012.150

Cited by 508 publications

(353 citation statements)

References 34 publications

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“…Recent advances in wavefront shaping have made this task a possibility [2][3][4][5][6][7][8][9][10][11][12] . By precompensating the optical wavefront, the light propagation can be controlled through and beyond scattering materials 2,3,13,14 .…”

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confidence: 99%

Super-resolution photoacoustic imaging through a scattering wall

et al. 2015

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The use of wavefront shaping to compensate for scattering has brought a renewed interest as a potential solution to imaging through scattering walls. A key to the practicality of any imaging through scattering technique is the capability to focus light without direct access behind the scattering wall. Here we address this problem using photoacoustic feedback for wavefront optimization. By combining the spatially non-uniform sensitivity of the ultrasound transducer to the generated photoacoustic waves with an evolutionary competition among optical modes, the speckle field develops a single, high intensity focus significantly smaller than the acoustic focus used for feedback. Notably, this method is not limited by the size of the absorber to form a sub-acoustic optical focus. We demonstrate imaging behind a scattering medium using two different imaging modalities with up to ten times improvement in signal-to-noise ratio and five to six times sub-acoustic resolution.

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confidence: 99%

Super-resolution photoacoustic imaging through a scattering wall

et al. 2015

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“…The latter approach was first developed for imaging through opaque barriers [13][14][15], and also allows for imaging around corners [16,17]. The work of Velten et al [5] and, more recently, Buttafava et al [8] sets out to establish the 3D shape of a static hidden object by collecting the return scattered light with a streak camera or single-photon avalanche diode, respectively.…”

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confidence: 99%

Detection and tracking of moving objects hidden from view

et al. 2015

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The ability to detect motion and track a moving object hidden around a corner or behind a wall provides a crucial advantage when physically going around the obstacle is impossible or dangerous. Previous methods have demonstrated that is possible to reconstruct the shape of an object hidden from view. However, these methods do not enable the tracking of movement in real-time. We demonstrate a compact non-line-of-sight laser ranging technology that relies upon the ability to send light around an obstacle using a scattering floor and to detect the return signal from a hidden object with only a few seconds acquisition time. By detecting this signal with a single-photon avalanche diode (SPAD) camera, we follow the movement of an object located a meter away from the camera with centimetre precision. We discuss the possibility of applying this technology to a variety of real-life situations in the 1 near future.Recent years have seen remarkable advances in the field of image processing and data acquisition, allowing for a range of novel applications [1][2][3][4][5][6][7][8]. An exciting new avenue is using optical imaging techniques to observe and track objects that are both in movement and hidden from the direct line-of-sight. The ability to detect motion and track a moving object hidden from view would provide a crucial advantage when physically going around the obstacle is impossible or dangerous, for example to detect a person moving behind a wall or a car approaching from behind a blind corner.Techniques for imaging static objects that are hidden from view have been recently demonstrated relying on, for example, radar technology [9,10], variations of laser illuminated detection and ranging (LIDAR) [3,5,11,12], or speckle-based imaging. The latter approach was first developed for imaging through opaque barriers [13][14][15], and also allows for imaging around corners [16,17]. The work of Velten et al. [5] and, more recently, Buttafava et al. [8] sets out to establish the 3D shape of a static hidden object by collecting the return scattered light with a streak camera or single-photon avalanche diode, respectively. While remarkable 3D reconstruction of objects are achieved with these techniques, Buttafava et al. point out that the requirement for scanning and subsequent long acquisition times mean that their technique is currently unsuitable for imaging moving objects.Notwithstanding these ingenious imaging systems, locating the position of a hidden object in motion and monitoring its movement in real time remains to date a major challenge. We set out to solve the tracking problem and develop a technique based on both hardware and software implementations that are specifically designed for this 2 purpose. Our solution is based on a LIDAR-like approach where a single-photon avalanche diode (SPAD) camera [7,[18][19][20][21][22] is used to image light that is backscattered from beyond the direct line-of-sight (see Methods for camera details). The high temporal resolution of the camera relies on the fact that each indiv...

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“…We demonstrate here that acoustic metamaterials can also be useful for encoding independent acoustic signals coming from different spatial locations by creating highly frequency-dependent and spatially complex measurement modes (28), and aid the solution finding for the inverse problem. Such physical layer encoding scheme exploits the spatiotemporal degrees of freedom of complex media, which contribute to a variety of random scattering-based sensing and wave-controlling techniques (29)(30)(31)(32)) and a recently demonstrated radiofrequency metamaterial-based imager (33).…”

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Single-sensor multispeaker listening with acoustic metamaterials

Xie

Tsai

Konneker

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Designing a "cocktail party listener" that functionally mimics the selective perception of a human auditory system has been pursued over the past decades. By exploiting acoustic metamaterials and compressive sensing, we present here a single-sensor listening device that separates simultaneous overlapping sounds from different sources. The device with a compact array of resonant metamaterials is demonstrated to distinguish three overlapping and independent sources with 96.67% correct audio recognition. Segregation of the audio signals is achieved using physical layer encoding without relying on source characteristics. This hardware approach to multichannel source separation can be applied to robust speech recognition and hearing aids and may be extended to other acoustic imaging and sensing applications. metamaterials | cocktail party problem | compressive sensing T he "cocktail party" or multispeaker listening problem is inspired by the remarkable ability of the human's auditory system in selectively attending to one speaker or audio signal in a multiple-speaker noisy environment (1, 2). Over the past half a century (3), the quest to understand the underlying mechanism (4-6) and build functionally similar devices has motivated significant research efforts (4-8).Previously proposed engineered multispeaker listening systems generally fall into two categories. The first kind is based on audio features and linguistic models of speech. For example, harmonic characteristics, temporal continuity, onset/offset of speech units combined with hidden Markov language models can be used to group overlapping audio signals into different sources (7, 9, 10). The drawback of such an approach is that certain audio characteristics have to be assumed (e.g., nonoverlapping in spectrogram) and linguistic model-based estimation can be very computationally intensive. The second kind relies on multisensor arrays to spatially filter sources (11). The need for multiple transducers and system complexity are the major disadvantages of the second approach.In this work, we demonstrate a multispeaker listening system that separates overlapping simultaneous conversations by leveraging the wave modulation capabilities of acoustic metamaterials. Acoustic metamaterials are a broad family of engineered materials which can be designed to possess flexible and unusual effective properties (12, 13). In the past, acoustic metamaterials with high anisotropy (14, 15), extreme nonlinearity (16), or negative dynamic parameters (density, bulk modulus, refractive index) (17-20) have been realized. Applications such as scattering reducing sound cloak (21, 22), beam steering metasurface (23), and other wave manipulating devices (24-27) have been proposed and demonstrated. We demonstrate here that acoustic metamaterials can also be useful for encoding independent acoustic signals coming from different spatial locations by creating highly frequency-dependent and spatially complex measurement modes (28), and aid the solution finding for the inverse problem. Such ph...

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Looking around corners and through thin turbid layers in real time with scattered incoherent light

Cited by 508 publications

References 34 publications

Super-resolution photoacoustic imaging through a scattering wall

Super-resolution photoacoustic imaging through a scattering wall

Detection and tracking of moving objects hidden from view

Single-sensor multispeaker listening with acoustic metamaterials

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