Photon-counting compressive sensing laser radar for 3D imaging

Abstract

We experimentally demonstrate a photon-counting, single-pixel, laser radar camera for 3D imaging where transverse spatial resolution is obtained through compressive sensing without scanning. We use this technique to image through partially obscuring objects, such as camouflage netting. Our implementation improves upon pixel-array based designs with a compact, resource-efficient design and highly scalable resolution. © 2011 Optical Society of America OCIS codes: 280.3640, 100.6890, 110.3010, 110.3080. The use of lasers for ranging (lidar) has greatly improved spatial and longitudinal resolution in ranged detectors [1]. Traditional lidar systems are singlepixel devices that obtain transverse resolution via scanning. In the past decade, there has been much interest in replacing scanning with spatially resolving detectors to produce ranged cameras [2-4]. These devices rapidly acquire three-dimensional images and utilize range gating to reveal objects obscured behind foliage or other camouflaging materials. The primary challenge is developing detectors with useful spatial resolution, high sensitivity, and fast timing. The most successful approach to date is the use of arrays of avalanche photo-diodes operating in the spirit of a CCD camera. A variety of high resolution systems have been brought to market with linear mode avalanche photodiode (APD) arrays [5]. For best performance, however, it is desirable to instead operate the APDs in geiger-mode to count discrete, single-photon arrivals. These photon-counting detectors have single-photon precision and sensitivity that approaches the shot noise limit with subnano-second timing. Such an array was developed for the state-of-the-art Jigsaw system created at MIT Lincoln Labs [6], which has been field tested with impressive results. The Jigsaw sensor consists of a 32 × 32 array of APDs detecting single-photon arrivals in a time-of-flight (TOF) lidar configuration.While single geiger-mode APDs are well developed, high resolution arrays are difficult to fabricate and remain primarily a research subject. As such, they present pragmatic difficulties. The highest resolution commercially available sensor is only 32 × 32 pixels, with 32 × 128 in development [7,8]. Lincoln Labs has reported up to 64 × 256 pixels [9,10]. Jigsaw must incorporate prism-based scanning to improve its resolution and field-of-view. Current arrays also have limited spectral range with peak quantum efficiency in the midvisible spectrum. For ranging, significant supporting equipment is required to correlate each pixel with illuminating pulses. Because individual pixels are small and optical flux must be distributed across the entire array, shot noise is significant. At present, such arrays are generally resource heavy in development and implementation.We show that these difficulties can be resolved by applying single-pixel camera technology [11] to generate transverse spatial resolution. This technique, pioneered by Baraniuk, uses compressive sensing to detect images with a single detector [12]. Appro...

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