Evolving threats encountered by coalition forces in Operation Iraqi Freedom drive the need for innovations in airborne intelligence, surveillance, and reconnaissance capabilities. In many cases, disruptive capabilities are created by linking existing technologies and new radical technologies in a novel way. Some of the radical technologies used in achieving these disruptive capabilities are existing prototypes or one-of-a-kind systems that are thrust into the field to quickly react to emerging threats. Horned Owl is one such rapidly developed innovative technical solution designed to meet immediate battlefield needs. This paper focuses on two key areas of this initiative. The first is the innovation champion establishing a collaborative environment which fosters creativity and allows the project to mature the disruptive capability. The second is the practical implication, or challenges of deploying experimental systems in a battlefield environment. Discussions of these two areas provide valuable lessons to guide future innovation champions when presented with the dual task of balancing system maturation with meeting operational demand. Contents of this paper are not necessarily the official views of, or endorsed by the U.S. Government, the Department of Defense, or the Department of the Air Force.

Real time detection and identification of explosives at a standoff distance is a major issue in efforts to develop defense against so-called Improvised Explosive Devices (IED). It is recognized that the only technique, which is potentially capable to standoff detection of minimal amounts of explosives is laser-based spectroscopy. LDS activity is based on a combination of laser-based spectroscopic methods with orthogonal capabilities. Our technique belongs to trace detection, namely to its micro-particles variety. It is based on commonly held belief that surface contamination was very difficult to avoid and could be exploited for standoff detection. We has applied optical techniques including gated Raman and time-resolved luminescence spectroscopy for detection of main explosive materials, both factory and homemade. We developed and tested a Raman system for the field remote detection and identification of minimal amounts of explosives on relevant surfaces at a distance of up to 30 meters.

The spectroscopic detection of complex molecules, such as explosives, requires a much broader spectral tuning range of the employed laser compared to the well-established tunable diode laser spectroscopy of light molecules. In this paper we demonstrate a new type of spectrally-tunable laser modules, which enables an increase of the tuning range by at least one order of magnitude in comparison to the established current-temperature tuning techniques. This was achieved by increasing the operating temperature range through the use of a temperature-variable diamond submount. The module comprises a quantum cascade (QC) laser mounted on the diamond submount with an integrated heater element and temperature sensor, enabling a controlled temperature change of the laser between 77 K and 400 K at a rate of temperature change of up to 2500 K/s. The favorable temperature characteristics allow us to easily tune the laser wavelength on- and off-resonance with the characteristic absorption bands of the material to be detected. With the QC laser module we demonstrate the detection of surface contaminations of around 10 μg/cm² TNT performing imaging backscattering spectroscopy.

A system for mine detection in aerial images is considered as an interactive system in which the operator is responsible for making iterative queries to the database of images and analyzing the results. Preliminary, each image undergoes formal decomposition into a set of feature vectors. Each feature vector is calculated for every irregularity found at a scale-invariant salient point detection stage where a blob detector is used. Assuming that every small object in the image can be described by a single invariant feature vector calculated on a patch around the salient point, formalization of search algorithms is feasible. While the template-based search is straightforward in the terms of one object - one feature vector, we focus on another important option when searching for mines - similar object search. For similar object search a hierarchical clustering algorithm is considered. The mentioned steps of image processing as well as similar object search are illustrated by performing on aerial mine field images taken by an electronic camera from a height of 27 meters. Encouraging preliminary results lead to the formulated plan for future research. The developed algorithms are planned to be used in an image search engine allowing the operator to interactively search for mines in a database of aerial images in humanitarian de-mining operations.

Small underwater objects such as vehicles and divers can pose threats to fixed installations and ships. For ships, these threats are present both at sea and in harbors. Shallow underwater targets, including drifting mines, are difficult to detect with acoustic methods and thus complementary methods are required. If an airborne platform is available, some of those targets could be detected by passive optical means. However, for sensing from a ship or from land, optical detection can be highly improved by use of a pulsed laser system. We present simulated data of importance for the design of a lidar system with low incidence angle with respect to the water surface. We also present our first experimental data from underwater target detection with an incidence angle of 5 degrees.

Acoustic methods have been recently investigated for the detection of shallow landmines. Some plastic landmines have a flexible case which can made to vibrate by an airborne excitation like a loudspeaker. The soil-mine system shows a resonant behavior which is used as a signature to discriminate from other rigid objects. The mechanical resonance can be detected at the soil surface by a remote sensing systems like a laser interferometer. An equivalent physical model of the mine-soil system has been investigated having the known physical characteristics of mine simulants. The authors designed and built a test-object with known mechanical characteristics (mass, elasticity, damping factor). The model has been characterized in laboratory and the results compared with the classic mass-spring loss oscillator described by Voigt. The vibrations at the soil surface have been measured in various positions with a micro machined accelerometer. The results of the simulations for the acceleration of the soil-mine system agree well with the experiment. The calibrated mine model is useful to investigate the variation of the resonance frequency for various buried depths and to compare the results for different soils in different environmental conditions.

The latest development in IR-fibre optics enables us to expand the spectral range of process spectroscopy from 2μm out to 17μm (5000 to 600cm-1) i.e. into the most informative "finger-print" part of the spectrum. Mid-IR wavelength ranges from 2 to 6-10μm may be covered by Chalcogenide IR-glass CIR-fibres while Polycrystalline PIR-fibres made of Silver Halides solid solutions transmit 4-17 μm wavelength radiation. PIR-fibre immersion ATR probes and Transmission/Reflection probes had been manufactured and successfully tested with different FTIR spectrometers in the field of remote spectroscopy for forensic substances identification, chemical reaction control, and monitoring of exhaust or exhalation gases. Using these techniques no sample preparation is necessary for fibre probes to measure evanescent, reflection and transmission spectra, in situ and in real time. QCL spectrometer may be used as a portable device for multispectral gas analysis at 1ppb level of detectivity for various applications in environmental pollution monitoring.

We report the results of utilization of wide-gap photorefractive sillenite crystals as adaptive photodetectors (AP) for vibration measurements. The operation of the adaptive system of non-destructive testing was studied for the real operation conditions (diffusely scattering objects). The operation principle of AP is based on the effect of the non-steady-state photoelectromotive force (photo-EMF). The mechanism responsible for the effect can be described as follows. Illumination of wide-gap semiconductor by an interference pattern produces a non-uniform excitation of free carriers (photoconductivity grating). Diffusion of the photo-excited carriers towards the dark regions leads to charge redistribution between deep traps in the photoconductor. A space charge field grating arises. Small vibrations of the light pattern excite an alternating current through the crystal. The results of measurements of small vibration amplitudes and resonant frequencies of the diffusely scattering objects are given. The presented adaptive interferometric system is suitable for industrial applications.

In this paper we study the potential of using deconvolution techniques on full-waveform laser radar data for pulse detection in cluttered environments, e.g. when a land-mine is partly occluded by vegetation. A pulse width greater than the distance between the reflecting surfaces within the footprint results in a signal that is composed by overlapping reflections that may be very difficult to analyze successfully with standard pulse detection techniques. We demonstrate that deconvolution improves the chance of successful decomposition of waveform signals into the components corresponding to the reflecting objects in the path of the laser beam. Experimental data were analyzed in terms of pulse extraction capability and distance accuracy. It was found that deconvolution increases the pulse extraction performance, but that surfaces closer than about 40% of the laser pulse width are still very difficult to detect and that the number of spurious, erroneously extracted, points is the price to pay for increased pulse detection probability.

This paper deals with two fields related to active imaging system. First, we begin to explore image processing algorithms to restore the artefacts like speckle, scintillation and image dancing caused by atmospheric turbulence. Next, we examine how to evaluate the performance of this kind of systems. To do this task, we propose a modified version of the german TRM3 metric which permits to get MTF-like measures. We use the database acquired during NATO-TG40 field trials to make our tests.

Detection of fast moving objects is challenging. Even more challenging is accurately locating them in space. We present optical sensors that can locate fast moving objects that penetrate into virtual optical screens. Each sensor is composed of several laser sources and detectors, and the three-dimensional mapping is based on combinations of range measurements, triangulation and geometry.

The Intelligent Vision Agent System, IVAS, is a system for automatic target detection, identification and information processing for use in human activities surveillance. This system consists of multiple sensors, and with control of their deployment and autonomous servo. Finding the optimal configuration for these sensors in order to capture the target objects and their environment to a required specification is a crucial problem. With a stereo pair of sensors, the 3D space can be discretized by an iso-disparity surface, and the depth reconstruction accuracy of the space is closely related to the iso-disparity curve positions. This paper presents a method to enable planning the position of these multiple stereo sensors in indoor environments. The proposed method is a mathematical geometry model, used to analyze the isodisparity surface. We will show that the distribution of the iso-disparity surface and the depth reconstruction accuracy are controllable by the parameters of such model. This model can be used to dynamically adjust the positions, poses and baselines lengths of multiple stereo pairs of cameras in 3D space in order to get sufficient visibility and accuracy for surveillance tracking and 3D reconstruction. We implement the model and present uncertainty maps of depth reconstruction calculated while varying the baseline length, focal length, stereo convergence angle and sensor pixel length. The results of these experiments show how the depth reconstruction uncertainty depends on stereo pair's baseline length, zooming and sensor physical properties.

Spacecraft docking, landing and star tracking are critical operations in various space missions. Docking provides the opportunity to joint two vehicles in order to change crews and deliver resources to a spacecraft. One of the main challenges in docking is to perform real-time tracking of the docking point for a precise and rapid feedback to the control system in order to achieve reliable operations. The same requirements are found for landing operations and star-tracking with main difference that the ground or sky is used for position and attitude tracking. Docking operations found multiple earth counterpart applications. Many of these earth-based applications concern the use of robotic devices to grab a specific object. In these cases various location parameters of the object are needed, such as rotation angle, scale and position. INO has developed a compact lightweight optical correlator prototype. This prototype provides a tool for the evaluation of various applications. In collaboration with ESA, INO studied the use of an optical correlator for selected space applications such as rendez-vous and docking, landing and star tracking operations. Optical correlator provides beyond real-time image processing capabilities and is well suited for target identification and positioning purpose. The optical correlator also shows low power consumption. In this paper, the latest analyses of the docking and landing applications are presented. For evaluation purpose, video sequences of Soyuz docking the International Space Station (ISS) were used. In the case of landing, moon images acquired in the SMART-1 mission, during its last orbits, were used. Mt. Wilson telescope images were used for star tracking examples.

The Super-resolution Sensor System (S³) program is an ambitious effort to exploit the maximum information a laser-based sensor can obtain. At Lockheed Martin Coherent Technologies (LMCT), we are developing methods of incorporating multi-function operation (3D imaging, vibrometry, polarimetry, aperture synthesis, etc.) into a single device. The waveforms are matched to the requirements of both hardware (e.g., optical amplifiers, modulators) and the targets being imaged. The first successful demonstrations of this program have produced high-resolution, three-dimensional images at intermediate stand-off ranges. In addition, heavy camouflage penetration has been successfully demonstrated. The resolution of a ladar sensor scales with the bandwidth as dR = c/(2B), with a corresponding scaling of the range precision. Therefore, the ability to achieve large bandwidths is crucial to developing a high-resolution sensor. While there are many methods of achieving the benefit of large bandwidths while using lower bandwidth electronics (e.g., an FMCW implementation), the S³ system produces and detects the full waveform bandwidth, enabling a large set of adaptive waveforms for applications requiring large range search intervals (RSI) and short duration waveforms. This paper highlights the combined three-dimensional imaging and vibrometry demos.

Present-day naval operations take place in coastal environments as well as narrow straits all over the world. Coastal environments around the world are exhibiting a number of threats to naval forces. In particular a large number of asymmetric threats can be present in environments with cluttered backgrounds as well as rapidly varying atmospheric conditions. In these conditions the threat contrast may be low and varying, and the amount of background clutter can be severe. These conditions require the electro-optical means of detection and classification to be optimized in order to have more time to act against threats. In particular the assessment of classification means is an important issue. Beside short-range coastal paths, long-range horizontal paths with variable atmospheric conditions are of interest. The small differences between types of vessel can help us determine the classification of the vessel type. Different payloads and people on-board can be clues to the classification of the vessel. Operations in warmer environments, limiting the atmospheric transmission due to water vapour absorption, are challenging. Understanding of the impact of the different environments on the optical characteristics of threats is of great importance. For this purpose a trial was planned to assess the optical characteristics of different types of small surface vessels in a coastal environment. During this trial a number of small targets were used during different parts of the day and night. Furthermore positional as well as atmospheric characterisation was performed as ground truth information. From this data a first analysis was performed showing strong intensity fluctuation in target as well as background signal levels. At longer ranges and in coastal environments these target signals may well be hidden within the background clutter. This data is essential to feed models for the assessment of sensor performance in coastal environment.

Many of the more challenging goals set for future defence systems require a paradigm shift in remote sensing technology. Some of these arise because of changes in the nature of conflict, whilst others are due to the increased emphasis in the use of unmanned platforms, especially in relation to the provision of persistent surveillance. Sensors are required to span the entire electromagnetic spectrum and the UK's Electro-Magnetic Remote Sensing Defence Technology Centre (EMRS DTC) is concerned with research in all relevant areas aimed at developing new military capabilities. This paper explains how the EMRS DTC is meeting many of these requirements, using examples derived from its own programme

This paper discusses Electro-Optic research activities from Electromagnetic Remote Sensing Defence Technology Centre (EMRS DTC) funded programmes which have enhanced Selex Sensors and Airborne Systems Ltd products. EMRS DTC EO Theme programmes relating to Broadband OPOs to reduce the coherence of laser sources for active imaging at 1.5μm, Intra-cavity Adaptive Optics Control of Lasers, Cost Reduction in 2D IR Detectors, Photonic Fibres for Active Sensor Systems, Novel low voltage InAs avalanche photodiodes for affordable 2D IR photodetectors and Hyperspectral Algorithm Development have been included in the discussion.

There is a need for faster processing hardware to provide modern radar systems with advanced capabilities such as multiple hypothesis tracking, real-time clutter removal and space-time adaptive beamforming (STAP) for jammer nulling. One approach that may help to meet this need is to use analogue methods in parts of the signal processing chain using optoelectronics. The vector-matrix multiplier is a powerful optical processing architecture that potentially offers very large gains in computation speed, but has not so far become commercially successful. This paper reports investigation of a novel arrangement for this type of processor that is aimed at improving the prospects for commercialisation, using guided-wave and micro-optic components. This approach will assist miniaturisation of the processor and improve ruggedness and scalability to large matrices.

Military applications such as electronic surveillance (ESM), intelligence (ELINT) and countermeasures (ECM) require real-time analysis of broadband RF signals, often with very high frequency resolution. Direct sampling and digitisation, followed by Fourier analysis and signal processing, will enable such signals to be analysed with much higher resolution than can be achieved with conventional microwave techniques. Direct sampling and digitisation of signals at frequencies above a few GHz is difficult to achieve electronically because the rise and fall times of electrical sampling gates are too long. This can be overcome by using a low-jitter optical sampling pulse train to measure the voltage on an electro-optic modulator. Optical sampling pulses can be very much shorter than electrical sampling pulses because of the large optical carrier frequency. In this paper we describe a novel multiple wavelength optical sampling system architecture for the real-time digitising of microwave signals between 1 and 20 GHz with a target resolution of more than 10 effective bits (>60 dB spurious free dynamic range). We also describe our work on making highly linear electro-optic modulators for this and other microwave-photonic applications.

Many military radar applications call for improved fidelity and shorter timescales in difficult environments of high background clutter. This paper examines the design of an LO for general radar applications with very large phase noise and stability improvements over quartz based systems (>50 dB) using fibre-laser based clockworks and oscillators. The examination is based around a strawman architecture to exploit the division of very high frequency optical standards (laser lines at 450 or 250 THz) to microwave frequencies and the consequential high phase noise improvement factors (~100 dB). The design utilises guided systems (fibre lasers and all other components in fibre) as far as possible to provide an easier to achieve, rugged and portable system. The design also uses improved non-linear super-continuum generation components, which require less laser power to drive them (from 100's of mW to 10 mW thus removing the need for optical power amplification). The use of direct diode pumped fibre-lasers reduces inefficiency as compared with solid-state free space lasers to make the system low power and air-cooled.

Glow discharge plasma, deriving from direct current gas breakdown, was investigated in order to realize an inexpensive THz room temperature detector. Preliminary results for THz radiation show that glow discharge indicator lamps as room temperature detectors yield good responsivity and NEP. Development of a Focal Plane Array (FPA) using such devices as detectors is advantageous since the costs of glow discharge detector is around $0.2-$0.5 per lamp, and the FPA images will be diffraction limited. The detection mechanism of the glow discharge detector was found to be enhanced diffusion current which causes decrease of glow discharge detector bias current when exposed to THz radiation.

We attempt to perform real time detection and direct high resolution imaging of millimeter blackbody sources using sparse aperture interferometry. We reject heterodyne technology for a multitude of factors including bulky equipment, cryogenic cooling, long integration times, and indirect imaging. An alternative method is to convert the incoming millimeter waves into optical and perform optical image-plane interferometry in real time. This method is suitable for snapshot-imaging of short-lived phenomena, often encountered in defense and security applications. The approach presented in this work utilizes a millimeter wave antenna array coupled to an optical interferometer which images directly on a detector array for image read-out, processing, and storage. To minimize the maximum sidelobes of the point spread function, we choose an antenna array composed of two concentric hexagonal rings, such that the outer ring is ~3 times the inner ring. This design ensures more or less uniform and isotropic spatial frequency coverage, eliminating difficulties associated with resolving out structures whose spatial frequencies are in between that of the single aperture diameter and those of the baselines. The Fourier coverage of this array is the sum of the Fourier coverage of the outer ring plus that of the inner ring added to that of the baselines between the inner and outer rings. The need for delay lines is done away with by mounting all the apertures on the same plane. The incoming millimeter signals are fed through electro-optical modulators for upconversion onto an optical carrier, which can be readily captured, routed, and processed using optical techniques. The optical waves are fed via a fiber optic array onto a microlens array which is a scaled down version of the antenna array configuration. Then homodyne interferometry is performed. We reject pupil-plane (Michelson) interferometry based on a multitude of factors. The main drawback is that pupil-plane interferometers don't produce images but rather gives the information about the autocorrelation of the object. We instead use a classical image-plane interferometer (Fizeau) setup and direct detection is performed on a detector array. Image-plane interferometry has its advantages. Unlike its pupil-plane cousin, a Fizeau interferometer is a true imaging device, where each beam is used to make an image of the object and are superimposed. Because Fizeau beam combiners work in the image plane, they don't suffer from ambiguities associated with the interpretation of visibility measurements. Also since the beams traverse the same paths and superpose, unmeasured phase changes do not creep in. In the design of the Fizeau interferometer, we preserve homothetic mapping, i.e., the entrance and exit pupils are replicas of one another, scaled only by a constant factor. This ensures direct imaging over a wide bandwidth with high angular resolution, high sensitivity, and a wide field of view. Since the Fizeau setup allows access to large fields, mosaicing wide fields is possible.

In previous publications, we have described a novel technique for millimeter-wave detection based on optical upconversion, carrier suppression, and photodetection. Using these techniques, we have been able to achieve NETD's as low as 1 K /√Hz in both 35 GHz and 95 GHz atmospheric transmission windows. These results were obtained without the use of millimeter-wave LNA's or cryogenic cooling, which have previously been requirements for reaching these performance levels. In this proceeding, we detail efforts to create a scanning single-pixel imager based on this detector technology. The configuration developed uses a larger 60 cm aperture in a Cassegrain configuration, which is mounted on a gimbal for far-field imaging. The described system has been used to collect data for perception experiments on the identification of small watercraft and some of the imagery collected in that experiment is presented herein. In addition, we discuss phenomenological observations noted during this data collection.

This paper reviews digital beam-forming as an alternative technology for the development of passive millimetre wave (PMMW) imagers. Considering recent technology developments and end-user requirements, digital beam-forming is an attractive prospect for a new architecture of PMMW security imager. The radiometric sensitivity in PMMW electronic beam-forming is investigated using beam-former simulations and comparisons made with a mechanical scanning PMMW imager. The objectives, design considerations and progress to date on a demonstrator programme for a PMMW digital beam-forming imager directed at the commercial security screening market are discussed. The benefits of digital beam-forming for security scanners are reviewed together with the calibration technique and the programme future.

We present a high-power frequency tripler for 110 GHz and a quintupler for 200-210 GHz. The tripler (×3), that is based on a single HBV diode, produces 240 mW of output power with a 3-dB bandwidth of 6%. This is the highest output power ever recorded for an HBV based multiplier irrespective of output frequency. The module features an ultra-compact waveguide block design, and a microstrip matching circuit on high-thermal-conductivity AlN to improve the power handling capability. Furthermore, we present an HBV quintupler (×5) that delivers more than 20 mW at 202 GHz.

Detection of biological warfare agents must be achieved as far upwind of their potential target as possible to provide the time necessary to adopt an effective protective posture. A small-scale fluorescence lidar has been designed and constructed by Dstl. The active element is a solid state Nd:YAG laser, the frequency of which is quadrupled to yield 266nm excitation of 9ns pulses with 40mJ energy. Fluorescence is collected from 300 to 500nm and is divided into 10 channels to investigate discrimination between common fluorescent interferent aerosols and biosimulants. The UV Laser Induced Fluorescence (LIF) LIDAR operated in trials to assess standoff biological detection systems at Dugway Proving Grounds, Utah, USA, participating in both breeze tunnel and open range trials. The collected biological simulant and interferent data has been utilised to train the discrimination algorithm and to assess the system's limit of detection and discrimination ability.

Sarnoff Corporation and the Naval Research Laboratory, through support of the U.S. Department of Homeland Security, are developing an automated, high throughput bio-aerosol physical enrichment system designed for use as part of a biological-threat protection system. The Biological Aerosol-Capture-Enrichment (BioACE) system is a bio-aerosol collection system that combines three unique technologies to create physically enriched aerosol samples that can be subsequently interrogated by any number of bio-threat detection systems for the presence of threat agents. An air-to-air concentrator uses an inertial separation technique to highly concentrate an aerosol sample presented to a dual wavelength ultra-violet laser induced fluorescence (UVLIF) optical trigger used to discriminate potential threat particles from non-threat particles conveyed in a collimated particle stream. This particle classification information is used to trigger an electrostatic deposition mechanism to deposit only those particles determined to be potential bio-threats onto a stainless steel substrate. Non-threat particles are discarded with the exiting airflow. The goal for the most recent development effort has been the integration and optimization of these technologies into a unit capable of producing highly enriched particulate samples from ambient air containing variable background aerosol loading and type. Several key technical and engineering challenges were overcome during the course of this development including a unique solution for compensating particle velocity dispersion within the airflow, development of a real-time signal acquisition and detection algorithm for determining material type on a particle by particle basis at rates greater than 2000 particles per second, and the introduction of a robust method for transferring deposited particulate into a 50ul wet sample suitable for most advanced bio-detection techniques. This paper will briefly describe the overall system architecture and then concentrate on the various component and system design tradeoffs required to optimize sample enrichment performance. A system performance model will be presented along with detailed analysis of the optical system components and electronic signal processing needed for achieving high concentration sample enrichment. Experimental methods and data obtained in the laboratory setting and from real world environments will be described and used to support the performance model of the system. Finally, a number of air sampling scenarios will be analyzed using the system performance model to determine the applicability of the BioACE system to the various concepts of operation perceived to be needed for achieving a high performance bio-threat detect-to-protect system.

Detection of biological threats in room air is a challenging problem due to their low concentration and the relatively high concentration of background. Dynamic sorting of threat particles from background clutter and dust prior to collection for analysis can provide substantially enriched samples with the advantages of greater analytical accuracy in shorter periods of time. The conceptually simple process of capturing threat particles and rejecting background in fact requires sophisticated particle detection and classification, timing, capture and final threat identification subsystems operating in concert. The effectiveness of the process is also strongly influenced by the operational conditions including threat and background loads as well as the time allotted for sample collection. The requirements of the final threat identification system will dictate the form factor for the collected sample and if collection is to be done dry or into a liquid. A number of sorting systems are currently under development to achieve enrichment for subsequent analysis. Enrichment factors, a common figure of merit for these systems, will be shown to be an inadequate indicator for comparing these systems unless standard operating conditions are used and other parameters are well defined. A set of parameters will be suggested that better allows characterization of the collection component of the sorting system.

Lidar has been identified as a promising sensor for remote detection of biological warfare agents. Elastic lidar can be used for cloud detection at long ranges and UV laser induced fluorescence can be used for discrimination of bioaerosols against naturally occurring aerosols. This paper analyzes the performance of elastic lidar such as sensitivity, range and angular coverage rate vs. atmospheric visibility, laser and receiver parameters. The analysis of the UV fluorescence lidar is concentrated on estimating the signal strength as a function of range, concentration and optical background level. The performance analysis supports the goal for a practical lidar system to detect 1000 particles/liter at 2-3 km using elastic backscatter and to verify the bioaerosol using fluorescence characterization at 1 km. Some examples of test results with an elastic lidar and a range gated imaging system both at 1.5 μm wavelength are presented together with fluorescence spectra of biological warfare agent simulants measured at an excitation wavelength of 355 nm.

An Optical Particle Counter (OPC) has been designed with a single ellipsoid reflector as the main optical element. Photodiodes with low noise transimpedance are used to detect forward and backscatter responses of particles scattering laser light (685 nm) at the ellipsoid focus. The Zemax® ray tracing program has been used to estimate the OPC's light collection efficiency. The design process has included modeling the optical response of various lenses, reflector coatings, and laser wavelengths. Simulations show that our OPC with a single ellipsoid reflector has 58.2% total efficiency for collecting forward and backscattered light.

Advanced IR emitters and sensors are under development for high detection probability, low false alarm rate and identification capability of toxic gases. One of the most reliable technique to identify the gas species is Spectroscopy, especially in the infrared spectral range, where most of existing toxic compounds exhibit their stronger roto-vibrational absorption bands. Following the results obtained from simulations and analysis of expected absorption spectra, a compact non dispersive infrared multi-spectral system has been designed and developed for security applications. It utilizes a few square millimeters thermal source, a novel design multipass cell, and a smart architecture microbolometric sensor array coupled to a linear variable spectral filter to perform toxic gases detection and identification. This is done by means of differential absorption spectroscopic measurements in the spectral range of the LWIR (Long Wavelength Infrared) spectral region. Preliminary tests for sensitivity and selectivity are undergoing using mixtures of ammonia and ethylene. Detection capability down to tens of ppm has been demonstrated. Possible improvements owing to open path sensor or hollow-fiber based sensor implementation are also presented for future systems evolution.

Results will be reported from efforts to develop a self-contained micromachined microfluidic detection system for the presence of specific target analytes under the US Office of Naval Research CIED Basic Research Program. Our efforts emphasize improving/optimizing a dedicated micromachined sensor array with integrated photodetectors that are coupled to chemically sensitized chemiluminescent receptors. Here we will review our work on the fabrication of integrated photodiodes within an array of micromachined silicon pyramidal cavities that will contain the chemiluminescent compounds. One particular advantage of such approach over a conventional planar photodiode would be its collection efficiency without the use of external optical components. This should allow a more compact and robust system to be constructed by integrating photodetection and fluidics into a single chip-based platform. Additionally, overview of accessing the photodiode using wireless coupling to a resonant chemically sensitive tag will be discussed.

Detection of radiological hazards in the solution phase using conventional means is considerably more difficult than in the gas phase. A new approach is required to provide a reliable, specific and low cost method of protecting sensitive national assets, such as water supplies, from a terrorist dirty bomb attack. Fibre optic sensors provide the required speed of response, the optical platforms are mature and of relatively low cost with proven reliability in the field. This paper describes the combination of a low cost sensor platform and smart sensor molecule (Isoamethyrin) for the selective determination of uranyl and other actinide species in water at sub ppm levels. Isoamethyrin is a synthetic porphyrin which has been demonstrated to show high selectivity for uranyl ions with an associated colour change on complexation. Fibre optic sensors are created by revealing an evanescent wave in a section of the fibre and covalently bonding the isoamethyrin to the fibre surface in this region. Colour changes occurring as a result of interaction between isoamethyrin and uranyl ions are monitored over 3 wavelength ranges covering the red, green and blue regions of the visible spectrum. Sensors created in this manner were found to be fast responding (<5s), sensitive (detection threshold <500ppb), specific (response restricted to certain actinides and lanthanides) and low cost.

Standoff detection, identification and quantification of chemical agents are fundamental needs in several fields of applications. Additional required sensor characteristics include high sensitivity, low false alarms and high-speed (ideally real-time) operation, all in a compact and robust package. The thermal infrared portion of the electromagnetic spectrum has been utilized to implement such chemical sensors, either with spectrometers (with none or moderate imaging capability) or with imagers (with moderate spectral capability). Only with the recent emergence of high-speed, large format infrared imaging arrays, has it been possible to design chemical sensors offering uncompromising performance in the spectral, spatial, as well as the temporal domain. Telops has developed an innovative instrument that can not only provide an early warning for chemical agents and toxic chemicals, but also one that provides a "Chemical Map" in the field of view. To provide to best field imaging spectroscopy instrument, Telops has developed the FIRST, Field-portable Imaging Radiometric Spectrometer Technology, instrument. This instrument is based on a modular design that includes: a high- performance infrared FPA and data acquisition electronics, onboard data processing electronics, a high- performance Fourier transform modulator, dual integrated radiometric calibration targets and a visible boresight camera. These modules, assembled together in an environmentally robust structure, used in combination with Telops' proven radiometric and spectral calibration algorithms make this instrument a world-class passive standoff detection system for chemical imaging. This paper presents chemical detection and identification results obtained with the FIRST sensor.

The development of commercial portable lab-on-chip (LOC) applications based on optical detection is hindered by the lack of imaging systems that can be directly integrated into the chip itself. Currently, fluorescence/luminescence signals are read out with power-hungry, bulky and expensive off-chip imaging systems, like CCD cameras or photomultiplier tubes. Here we present an enabling technology that for the first time allows cheap and easy integration of imaging systems directly into disposable lab-on-chip systems. Our technology is based on organic semiconductor materials that can be processed in liquid form by inkjet printing, in a process much faster and cheaper than the complicated fabrication of silicon-based imaging sensors. Organic photosensors can be printed on various substrate materials like plastic foil or glass or directly onto lab-on-chip systems. The ultrathin photodiodes with an overall thickness of only 300 to 500 nm show quantum efficiencies better than 0.5 and linear light-response over 6 orders of magnitude. The pixel size can range from 50 to over 1000 μm and inkjet fabrication allows tailoring the sensor layout to the needs of the specific application.

We present a new photonic technology and demonstrate that it allows for precise immobilisation of biomolecules to sensor surfaces. The technology secures spatially controlled molecular immobilisation since immobilisation of each molecule to a support surface can be limited to the focal point of the ultraviolet (UV) beam, as small as a few micrometers. We can immobilise molecules according to any pattern, from classical microarrays to diffraction patterns creating unique watermarking safety patterns. Given that suitable protein markers exists for all relevant diseases it is entirely feasible to test for a range of disease indicators (antigens and other markers) in a single test. Few micrometer spotsize allows for a virtually unlimited number of protein spots in a multipotent microarray. This new technology produces radically new photonics based microarray sensing technology and watermarking and has clear potential for biomedical, bioelectronic, surface chemistry, security markers production, nanotechnology and therapeutical applications. We also show an in depth analyses of the immobilized patterns and of the microarrays with our software BNIP Pro.

Wide-bandgap GaN-based avalanche photodetectors (APDs) are important for photodetectors operating in UV spectral region. For the growth of GaN-based heteroepitaxial layers on lattice-mismatched substrates such as sapphire and SiC, a high density of defects is introduced, thereby causing device failure by premature microplasma breakdown before the electric field reaches the level of the bulk avalanche breakdown field, which has hampered the development of III-nitride based APDs. In this study, we investigate the growth and characterization of GaN and AlGaN-based APDs on bulk GaN and AlN substrates. Epitaxial layers of GaN and Al_xGa_1-xN p-i-n ultraviolet avalanche photodiodes were grown by metalorganic chemical vapor deposition (MOCVD). Improved crystalline and structural quality of epitaxial layers was achieved by employing optimum growth parameters on low-dislocation-density bulk substrates in order to minimize the defect density in epitaxially grown materials. GaN and AlGaN APDs were fabricated into 30μm- and 50μm-diameter circular mesas and the electrical and optoelectronic characteristics were measured. APD epitaxial structure and device design, material growth optimization, material characterizations, device fabrication, and device performance characteristics are reported.

Monitoring of personal wellbeing and optimizing human performance are areas where sensors have only begun to be used. One of the reasons for this is the specific demands that these application areas put on the underlying technology and system properties. In many cases these sensors will be integrated in clothing, be worn on the skin, or may even be placed inside the body. This implies that flexibility and wearability of the systems is essential for their success. Devices based on polymer semiconductors allow for these demands since they can be fabricated with thin film technology. The use of thin film device technology allows for the fabrication of very thin sensors (e.g. integrated in food product packaging), flexible or bendable sensors in wearables, large area/distributed sensors, and intrinsically low-cost applications in disposable products. With thin film device technology a high level of integration can be achieved with parts that analyze signals, process and store data, and interact over a network. Integration of all these functions will inherently lead to better cost/performance ratios, especially if printing and other standard polymer technology such as high precision moulding is applied for the fabrication. In this paper we present an optical transmission sensor array based on polymer semiconductor devices made by thin film technology. The organic devices, light emitting diodes, photodiodes and selective medium chip, are integrated with classic electronic components. Together they form a versatile sensor platform that allows for the quantitative measurement of 100 channels and communicates wireless with a computer. The emphasis is given to the sensor principle, the design, fabrication technology and integration of the thin film devices.

The interest in on-line water quality monitors has increased significantly in the last years, because of the need for rapid, reliable and continuous monitoring. This has resulted in the introduction of new monitors which can provide (near) real-time information on water quality. They can be used for continuous river water quality control as well as for drinking water protection against intentional contamination. Still no universal monitor is yet available which is able to protect against all kinds of threats. The combination of complementary systems into a single integrated monitoring platform would greatly enhance the applicability of real time monitoring devices. Such a combination should be found in the complementary information derived from a chemical analytical technique and from an effect monitor (biomonitor). Where a chemical analytical monitoring system identifies and quantifies specific water contaminants, biomonitoring gives an indication of the total quality, including the effects of unknown toxic substances. This combination was found in using the TOXcontrol, a biological toxicity monitor using luminescent bacteria, and the s::can spectro::lyser^TM, a submersible UV-VIS spectrophotometer probe, to evaluate drinking water safety. This combination allows for the verification of alarm signals from one instrument with the signal of the other, reducing false alarm rates. Experiments were performed in a laboratory setting and in a field test. It is concluded that the combination of the UV-VIS spectrophotometer and the toxicity biomonitor comprises a monitoring system with a high added value being capable of detecting a broad range of contaminants at low concentrations.

In this paper we describe a novel technique for the fabrication of aluminosilicate microfibres and microtubes which are shown to act as optical cylindrical microresonators. The alumosilicate microfibres and microtubes were fabricated by using vacuum-assisted wetting and filtration of silica gel through a microchannel glass matrix. The microfibres and microtubes were studied using Scanning Electron Microscopy (SEM), micro-photoluminescence spectroscopy and fluorescence lifetime imaging confocal microscopy. In the emission spectra of the micro-resonators we find very narrow periodic peaks corresponding to the whispering gallery modes of two orthogonal polarizations with quality factors up to 3200. A strong enhancement in photoluminescence decay rates at high excitation power demonstrates the occurrence of amplified spontaneous emission from a single microtube. These microtubes show a large evanescent field extending many microns beyond the tube radius. Potential applications for these novel microresonators will be in the area of optical microsensors for a single molecule detection of biological and chemical species, including anti-terrorism and defense sectors.

This paper reports on the development of optically based techniques to detect and identify chemical agents. Detection sensitivity and molecule discrimination are studied. In parallel, efforts are made to develop rugged and compact experimental designs that can be used for field measurements. Laser Induced breakdown spectroscopy (LIBS) is a surface analyzing optical technique investigated to measure sarin like molecules deposited on samples coming from the Parisian subway. On the other hand, Tunable Diode Laser Spectroscopy (TDLS) - Cavity Ring-Down Spectroscopy (CRDS) or Cavity Enhanced Absorption Spectroscopy (CEAS) - is used to measure traces of the industrial toxic hydrogen fluoride gas down to the ppb level. Measurements in laboratory are reported and primary results obtained in a field experiment are described.