PT  - JOURNAL ARTICLE
AU  - Kirmani, Ahmed
AU  - Venkatraman, Dheera
AU  - Shin, Dongeek
AU  - Colaço, Andrea
AU  - Wong, Franco N. C.
AU  - Shapiro, Jeffrey H.
AU  - Goyal, Vivek K
TI  - First-Photon Imaging
AID  - 10.1126/science.1246775
DP  - 2014 Jan 03
TA  - Science
PG  - 58--61
VI  - 343
IP  - 6166
4099  - http://science.sciencemag.org/content/343/6166/58.short
4100  - http://science.sciencemag.org/content/343/6166/58.full
SO  - Science2014 Jan 03; 343
AB  - Firing off a burst of laser pulses and detecting the back-reflected photons is a widely used method for constructing three-dimensional (3D) images of a scene. Kirmani et al. (p. 58, published online 29 November) describe an active imaging method in which pulsed laser light raster scans a scene and a single-photon detector is used to detect the first photon of the back-reflected laser light. Exploiting spatial correlations of photons scattered from different parts of the scene allows computation of a 3D image. Importantly, for biological applications, the technique allows the laser power to be reduced without sacrificing image quality. Imagers that use their own illumination can capture three-dimensional (3D) structure and reflectivity information. With photon-counting detectors, images can be acquired at extremely low photon fluxes. To suppress the Poisson noise inherent in low-flux operation, such imagers typically require hundreds of detected photons per pixel for accurate range and reflectivity determination. We introduce a low-flux imaging technique, called first-photon imaging, which is a computational imager that exploits spatial correlations found in real-world scenes and the physics of low-flux measurements. Our technique recovers 3D structure and reflectivity from the first detected photon at each pixel. We demonstrate simultaneous acquisition of sub–pulse duration range and 4-bit reflectivity information in the presence of high background noise. First-photon imaging may be of considerable value to both microscopy and remote sensing.