Publications

Geiger-mode avalanche photodiodes (GMAPDs) are capable of detecting single photons. They can be operated to directly trigger all-digital circuits, so that detection events are digitally counted or time stamped in each pixel. An imager based on an array of GMAPDs therefore has zero readout noise, enabling quantum-limited sensitivity for photon-starved...

An uncooled thermal imager is being developed based on a liquid crystal transducer. The liquid crystal transducer changes a long-wavelength infrared scene into a visible image as opposed to an electric signal in microbolometers. This approach has the potential for making a more flexible thermal sensor. One objective is to...

We report on two recently developed charge-coupled devices (CCDs) for adaptive optics wavefront sensing, both designed to provide exceptional sensitivity (low noise and high quantum efficiency) in high-frame-rate low-latency readout applications. The first imager, the CCID75, is a back-illuminated 16-port 160x160 pixel CCD that has been demonstrated to operate at...

We describe a new sensor that combines dynamic pupil coding with a digital readout integrated circuit (DROIC) capable of modulating a scene with a global or per-pixel time-varying, pseudo-random, and duo-binary signal (+1-1,0).

Gigahertz (GHz) imaging technology will be needed at high-luminosity X-ray and charged particle sources. It is plausible to combine fast scintillators with the latest picosecond detectors and GHz electronics for multi-frame hard X-ray imaging and achieve an inter-frame time of elss than 10 ns. The time responses and light yield...

Tactical high-energy laser (HEL) systems face a range of imaging-related challenges in wavefront sensing, acquiring and tracking targets, selecting the HEL aimpoint, and assessing lethality. Accomplishing these functions in a timely fashion may be limited by competing requirements on total field of regard, target resolution, signal to noise, and focal...

We present an approach for rational design and optimization of plasmonic arrays for ultrasensitive surface enhanced infrared absorption (SEIRA) spectroscopy of specific protein analytes. Motivated by our previous work that demonstrated sub-attomole detection of surface-bound silk fibroin [Proc. Natl. Acad. Sci. U.S.A. 106, 19227 (2009)], we introduce here a general...

We have developed a remote detection system consisting of commercially available retroreflective material coated with an analyte-specific colorimetric dye. Quantitative performance modeling predicts that, given the appropriate indicator dye, a system with a 10 cm optic and eye-safe illumination should be capable of detecting small droplets of contamination at kilometer...

We designed and constructed a system that includes aircraft, ground vehicles, and throwable sensors to search a semiforested region that was partially covered by foliage. The system contained 4 radio-controlled (RC) trucks, 2 aircraft, and 30 SensorMotes (throwable sensors). We also investigated communications links, search strategies, and system architecture. Our...

We have demonstrated a wafer-scale back-illumination process for silicon Geiger-mode avalanche photodiode arrays using Molecular Beam Epitaxy (MBE) for backside passivation. Critical to this fabrication process is support of the thin ( 10 um) detector during the MBE growth by oxide-bonding to a full-thickness silicon wafer. This back-illumination process makes...