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Simultaneous dynamic pupil coding with on-chip coded aperture temporal imaging

Published in:
SRS 2014: Signal Recovery and Synthesis Conf., 13-17 June 2014.

Summary

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).
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Summary

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).

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Gigahertz (GHz) hard X-ray imaging using fast scintillators

Summary

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 of LYSO, LaBr3, BaF2 and ZnO are measured using an MCP-PMT detector. Zinc Oxide (ZnO) is an attractive material for fast hard X-ray imaging based on GEANT4 simulations and previous studies, but the measured light yield from the samples is much lower than expected.
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Summary

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...

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Pixel-processing imager development for directed energy applications

Summary

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 plane readout bandwidth. In this paper, we explore the applicability of an emerging pixel-processing imager (PPI) technology to these challenges. The on-focal-plane signal processing capabilities of the MIT Lincoln Laboratory PPI technology have recently been extended in support of directed energy applications. We describe this work as well as early results from a new PPI-based short-wave-infrared focal plane readout capable of supporting diverse applications such as low-latency Shack-Hartmann wavefront sensing, centroid computation, and Fitts correlation tracking.
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Summary

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...

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Rational design and optimization of plasmonic nanoarrays for surface enhanced infrared spectroscopy

Published in:
Opt. Express, Vol. 20, No. 11, 21 May 2012, pp. 11953-11966.

Summary

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 framework that allows for the numerical optimization of metamaterial sensor designs in order to maximize the absorbance signal. A critical feature of our method is the explicit compensation for the perturbative effects of the analyte's refractive index which alters the resonance frequency and line-shape of the metamaterial response, thereby leading to spectral distortion in SEIRA signatures. As an example, we leverage our method to optimize the geometry of periodic arrays of plasmonic nanoparticles on both Si and CaF2 substrates. The optimal geometries result in a three-order of magnitude absorbance enhancement compared to an unstructured Au layer, with the CaF2 substrate offering an additional factor of three enhancement in absorbance over a traditional Si substrate. The latter improvement arises from increase of near-field intensity over the Au nanobar surface for the lower index substrate. Finally, we perform sensitivity analysis for our optimized arrays to predict the effects of fabrication imperfections. We find that
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Summary

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...

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Retroreflectors for remote readout of colorimetric sensors

Published in:
Sensors and Actuators B-Chemical, Vol. 160, No. 1, 15 December 2011, pp. 1244-1249.

Summary

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 ranges. We have synthesized new colorimetric dyes specific to organophosphate contamination and, with these dyes, demonstrated detection of 1um of liquid malathion at over 150 m with less than 20 mW of laser illumination.
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Summary

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...

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Distributed multi-modal sensor system for searching a foliage-covered region

Summary

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 system is designed to be low-cost, contain a variety of sensors, and distributed so that the system is robust even if individual components are lost.
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Summary

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...

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MBE back-illuminated silicon Geiger-mode avalanche photodiodes for enhanced ultraviolet response

Published in:
SPIE Vol. 8033, Advanced Photon Counting Techniques V, 25 April 2011, 80330D.

Summary

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 it possible to build low-dark-count-rate single-photon detectors with high quantum efficiency extending to deep ultraviolet wavelengths. This paper reviews our process for fabricating MBE back-illuminated silicon Geigermode avalanche photodiode arrays and presents characterization of initial test devices.
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Summary

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...

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Bioinspired resource management for multiple-sensor target tracking systems

Summary

We present an algorithm, inspired by self-organization and stigmergy observed in biological swarms, for managing multiple sensors tracking large numbers of targets. We devise a decentralized architecture wherein autonomous sensors manage their own data collection resources and task themselves. Sensors cannot communicate with each other directly; however, a global track file, which is continuously broadcast, allows the sensors to infer their contributions to the global estimation of target states. Sensors can transmit their data (either as raw measurements or some compressed format) only to a central processor where their data are combined to update the global track file. We outline information-theoretic rules for the general multiple-sensor Bayesian target tracking problem. We provide specific formulas for problems dominated by additive white Gaussiannoise. Using Cramer-Rao lower bounds as surrogates for error covariances, we illustrate, using numerical scenarious involving ballistic targets, that the bioinspired algorithm is highly scalable and peforms very well for large numbers of targets.
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Summary

We present an algorithm, inspired by self-organization and stigmergy observed in biological swarms, for managing multiple sensors tracking large numbers of targets. We devise a decentralized architecture wherein autonomous sensors manage their own data collection resources and task themselves. Sensors cannot communicate with each other directly; however, a global track...

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A multi-frame, megahertz CCD imager

Published in:
IEEE Trans. Nuclear Sci., Vol. 56, No. 3, June 2009, pp. 1188-1192.

Summary

The Los Alamos National Laboratory's Dual Axis Radiographic Hydrodynamic Test Facility (DARHT) generates flash radiographs of explosive experiments using two linear induction electron accelerators situated at right angles. The DARHT second axis accelerator generates an 18-MeV, 2 kA, 2 sec electron beam which is converted or "chopped" into four individual pulses ranging from 20 to 100 nsec in length at 2 MHz frequency. The individual electron beam pulses are down-converted by a segmented lutetium oxyorthosilicate scintillator, creating four visible light flashes, to image explosively driven events. To record these events, a high efficiency, high speed, imager has been fabricated which is capable of framing rates of 2 MHz. This device utilizes a 512 512 pixel charge coupled device (CCD) with a 25 cm2 active area, and incorporates an electronic shutter technology designed for back-illuminated CCD's, making this the largest and fastest back-illuminated CCD in the world. Characterizing an imager capable of this frame rate presents unique challenges. High speed LED drivers and intense radioactive sources are needed to perform basic measurements.We investigate properties normally associated with single-frame CCDs such as read noise, gain, full-well capacity, detective quantum efficiency (DQE), sensitivity, and linearity. In addition, we investigate several properties associated with the imager's multi-frame operation such as transient frame response and frame-to-frame isolation while contrasting our measurement techniques and results with more conventional devices.
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Summary

The Los Alamos National Laboratory's Dual Axis Radiographic Hydrodynamic Test Facility (DARHT) generates flash radiographs of explosive experiments using two linear induction electron accelerators situated at right angles. The DARHT second axis accelerator generates an 18-MeV, 2 kA, 2 sec electron beam which is converted or "chopped" into four individual...

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A 64 x 64-pixel CMOS test chip for the development of large-format ultra-high-speed snapshot imagers

Summary

A 64 x 64-pixel test circuit was designed and fabricated in 0.18- m CMOS technology for investigating high-speed imaging with large-format imagers. Several features are integrated into the circuit architecture to achieve fast exposure times with low-skew and jitter for simultaneous pixel snapshots. These features include an H-tree clock distribution with local and global repeaters, single-edge trigger propagation, local exposure control, and current-steering sampling circuits. To evaluate the circuit performance, test structures are periodically located throughout the 64 x 64-pixel device. Measured devices have exposure times that can be varied between 75 ps to 305 ps with skew times for all pixels less than +-3 ps and jitter that is less than +-1.2 ps rms. Other performance characteristics are a readout noise of approximately 115 e- rms and an upper dynamic range of 310,000 e-.
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Summary

A 64 x 64-pixel test circuit was designed and fabricated in 0.18- m CMOS technology for investigating high-speed imaging with large-format imagers. Several features are integrated into the circuit architecture to achieve fast exposure times with low-skew and jitter for simultaneous pixel snapshots. These features include an H-tree clock distribution...

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