Nonlinear optical materials play a key role in the development of coherent sources of radiation as they permit the frequency conversion of mature solid-state lasers into spectral ranges where lasers do not exist or perform poorly. The availability of efficient Quasi-Phase-Matched infrared materials is thus considered as important for the development of several defense optronics applications. This paper will review the progress we achieved so far with periodically oriented Gallium Arsenide.

Semiconductor quantum well active structures are pervasive in many applications of defense related systems ranging from low power edge (DFB), VCSEL and VCSEL emitter arrays to high power low brightness broad area emitters and diode bars. Recent breakthroughs in the development of a new class of high brightness vertical external cavity (VECSEL) emitters offers the potential to replace solid state YAG kW-class laser weapons systems. Remarkably, despite the maturity and dramatic improvement in quality of semiconductor QW growth over the past three decades, there has been no truly predictive means of designing the semiconductor active structure and fast-tracking to a final packaged device. We will describe a fully self-consistent microscopic many-body approach to calculate optical gain, absorption, refractive index spectra and nonradiative recombination rates for a broad class of semiconductor quantum well material systems. The theoretical calculations are free of ad hoc parameter adjustments and provide, for the first time, a means of designing an active semiconductor epi-structure in a predictive manner.

Optically-pumped vertical external cavity semiconductor lasers offer the exciting possibility of designing kW-class solid state lasers that provide significant advantages over their doped YAG, thin-disk YAG and fiber counterparts. The basic VECSEL/OPSL (optically-pumped semiconductor laser) structure consists of a very thin (approximately 6 micron thick) active mirror consisting of a DBR high-reflectivity stack followed by a multiple quantum well resonant periodic (RPG) structure. An external mirror (reflectivity typically between 94%-98%) provides conventional optical feedback to the active semiconductor mirror chip. The "cold" cavity needs to be designed to take into account the semiconductor sub-cavity resonance shift with temperature and, importantly, the more rapid shift of the semiconductor material gain peak with temperature. Thermal management proves critical in optimizing the device for serious power scaling. We will describe a closed-loop procedure that begins with a design of the semiconductor active epi structure. This feeds into the sub-cavity optimization, optical and thermal transport within the active structure and thermal transport though the various heat sinking elements. Novel schemes for power scaling beyond current record performances will be discussed.

The aim of this work is to introduce the RTP material (a KTP isomorph) and point out its main fields of application for solid-state lasers, both in non-linear optics and electro-optics. In order to cover all the range of applications in which RTP can be used, the paper reviews the performance (efficiency, tolerance, walk-off, damage threshold) of the RTP crystals as frequency-doubling crystals (Second Harmonic Generation) for green and yellow lasers. In addition, red output was obtained with RTP in a frequency-mixing experiment, and an OPO (Optical Parametric Oscillation) pumped at 1064nm yielded an eye-safe wavelength at 1.62 μm. For both operations, we present data related to RTP's optical and physical properties as well as comparison with other suitable non linear crystals. With the help of the Photothermal Common-path Interferometer (a technique developed in order to measure very precisely all kinds of absorption), we give an assessment of RTP's sensitiveness to green-induced absorption ("grey-track"). This review ends by covering the properties of RTP for electro-optics. We present a complete study based on measurements in house and comparative data of other non linear crystals available on the market.

Optical parametric oscillators (OPOs) offer a route to powerful tunable output in the mid-infrared (mid-IR). Mid-IR OPOs exploit wavelength conversion of near-infrared lasers within non-linear optical materials. A new approach to engineering suitable non-linear OPO materials is being developed as an alternative to conventional chalcopyrite crystals such as ZnGeP₂. These new materials use commercially available, high-optical quality gallium arsenide (GaAs) wafers and a novel glass-bonding (GB) process to assemble quasi-phase matched (QPM) multilayer structures. The assembled QPM GaAs stack must have low optical loss and a large useable aperture and needs to be produced reliably with a minimum of 50 layers. Results from a recent sequence of 50-layer GBGaAs stack fabrication will be presented. Of the six stacks successfully bonded two had a useable aperture of approximately 20 mm² (40% of the maximum available). Of these, one has the lowest absorption and transmission loss per layer (0.07% measured at 2 μm) of any multi-layer glass-bonded QPM GaAs stack produced to date. By adjusting the load distribution at the edges of the stack during bonding the useable optical aperture was increased to nearly 90%. Results from non-linear wavelength conversion experiments into the mid-infrared using multi-layer GBGaAs crystals will be presented.

The laser efficiency of Ti³⁺:Al₂O₃ (Ti:Sapphire) is affected by residual absorption in the infrared region (800 nm) of the laser emission caused by Ti³⁺-Ti⁴⁺ pairs. Consequently, the ratio of the absorption coefficients at pump wavelength and at maximum of residual absorption forms the most important figure of merit (FoM) of Ti:Sapphire laser crystals. In general, to achieve sufficient FoM commercial Ti:Sapphire crystals are subject to a post-growth annealing under strongly reducing atmosphere to shift the balance between Ti³⁺ and Ti⁴⁺ ions in favour of the former ion. However, due to the low diffusion velocities under these conditions, this process is very time-consuming, especially for larger crystals. To save this step the crystal growth process of Ti:Sapphire was performed in a special gas mixture to stabilize the Ti³⁺ ions during the growth. The stability range of Ti³⁺ at growth temperature was estimated on the basis of thermodynamic equilibrium calculations. Ti³⁺ ions exist at about 2050°C only in very small "window" regarding the oxygen partial pressure. This "window" remains very small during cooling too. To meet these conditions, i.e. to create the optimum growth atmosphere the oxygen partial pressure of different gas mixtures was calculated. That way a gas mixture was found which allowed the growth of Ti:Sapphire crystals with diameter up to 55 mm and a FoM > 100 without subsequent annealing. Under these conditions the formation of aluminium suboxides and therewith of oxygen which can be trapped in the crystal as gaseous inclusions was suppressed efficiently.

EFG sapphire sheet measuring 305 x 510mm and 225 x 660mm have been produced in quantity. The average optical transmission of 6.15 mm thick uncoated polished panels is 84.0% ± 0.5 at 700 nm. This value assures good transmission throughout the 500 to 5000 nm spectral range. Effective absorption coefficients for this spectral range and thickness are calculated and presented. An average index inhomogeneity of 6 ppm ± 2 has been measured and is the requirement for panels polished to 0.1λ at this thickness (@633 nm).

Ytterbium-doped fibers are widely used in applications requiring short fiber amplifiers for high peak power pulse amplification. One of the key challenges posed on the performance and reliability of such amplifiers is mitigating photodarkening of the active fiber. Photodarkening manifests itself as a temporal increase in broadband absorption centered at visible wavelengths, and varies on how the active fiber has been manufactured. The tail of the photodarkening absorption extends to the 1μm region, thus in some cases seriously degrading the fiber efficiency over time. Accurate measurement methods for characterization of photodarkening must be developed in order to better understand its causes and create techniques to eliminate it so as to secure widespread commercialization of reliable Yb-doped fibers. This paper presents a simple method to characterize photodarkening in both single-mode and double clad Yb-doped fibers. A short length of fiber is pumped using high brightness source in order to achieve high and uniform inversion. The high inversion speeds up the formation of the color centers to the high degradation level, thus reducing the analyzing time from weeks to few of hours. With this method, photodarkening can be measured even from relatively short fibers by monitoring loss at visible wavelengths, where the degradation is greatest. We have analyzed the repeatability of the measurement method against the pumping conditions and fiber sample properties. The impact of photodarkening in different applications is discussed. We present the results of recent optimization of Liekki Yb1200 product family and also compare these with some other commercially available fibers.

Middle infrared lasers for countermeasures against heat seeking missiles are currently under development. These systems, based on diode pumped solid state lasers pumping optical parametric oscillators, are complex, bulky and expensive. Middle infrared fiber lasers in the 3 to 5 μm spectral region which operate without a need for frequency conversion may provide an attractive option. We have investigated the luminescence of silver bromide-chloride crystals and fibers doped with Pr³⁺ ions in the near and middle infrared spectral ranges. The emission, excitation, and absorption spectra, as well as the kinetic parameters, were measured over a broad temperature range. The crystal activation was produced by growing from the melt. No differences were found between the luminescence properties in the crystals and the fibers. The Judd Ofelt analysis was applied to the Pr doped crystals, and the transition rates, branching ratios, and the quantum efficiencies were calculated. Good agreement was obtained between the theory and the experiment. The strong middle infrared luminescence and the kinetic parameters of these crystals make them good candidates for the fabrication of fiber lasers in 4 -5.5μm spectral range. Such lasers would be very useful for countermeasure devices.

Optimization of the optical quality of optical-grade germanium components requires an in-depth investigation of the different contributions to the optical loss in germanium. In this paper we therefore focus on this optical characterization. We give an overview of possible characterization techniques to determine surface roughness, surface/bulk absorption and refractive index inhomogeneities and we highlight the obtained optical characteristics. To conclude we select the most appropriate non-destructive characterization tool for each optical parameter.

The motivation for use of organic electro-optic materials derives from (1) the inherently fast (sub-picosecond) response of π-electron systems in these materials to electrical perturbation making possible device applications with gigahertz and terahertz bandwidths, (2) the potential for exceptionally large (e.g., 1000 pm/V) electro-optic coefficients that would make possible devices operating with millivolt drive voltages, (3) light weight, which is a concern for satellite applications, and (4) versatile processability that permits rapid fabrication of a wide variety of devices including conformal and flexible devices, three dimensional active optical circuitry, hybrid organic/silicon photonic circuitry, and optical circuitry directly integrated with semiconductor VLSI electronics. The most significant concerns associated with the use of organic electro-optic materials relate to thermal and photochemical stability, although materials with glass transition temperatures on the order of 200°C have been demonstrated and photostability necessary for long term operation at telecommunication power levels has been realized. This communication focuses on explaining the theoretical paradigms that have permitted electro-optic coefficients greater than 300 pm/V (at telecommunication wavelengths) to be achieved and on explaining likely improvements in electro-optic activity that will be realized in the next 1-2 years. Systematic modifications of materials to improve thermal and photochemical stability are also discussed.

Suitable polymer-based photonic materials must possess the desired optical and electromagnetic properties for optimal device performance depending on the intended application. A new class of polymer, processed from purified deoxyribonucleic acid (DNA), has been investigated for use in photonic applications and has shown promise as an excellent optical waveguide material. In this paper we present the current optical and electronic properties of this new DNA-based biopolymer, including optical loss, temperature stability, refractive index, resistivity, dielectric constant and microwave insertion loss.

Polymer waveguides embedded in a printed circuit board offer a substantial increase in the achievable bandwidth density compared with today's electrical interconnects. We present our results on the polymer waveguide technology and the building blocks that perform the optoelectronic conversion. Specific challenges in integrating optics in a printed circuit board are addressed. Data transfer measurements are presented.

Monte Carlo Metropolis simulations of electro-optical phenomena in nematic liquid crystals (NLC) proposed in papers^{[1, 2]} are used to calculate the profiles of an inhomogeneous ordering of NLC molecules in twisted nematic systems. The important role of low anchoring forces is clearly demonstrated. The dependence of transmission of light propagating through a twisted NLC cell on applied electric field and light wavelength generalizes known result^[3] for an infinitely strong anchoring.

A non-covalent solubilization technique allowed us to synthesize original compositions such as suspensions of astralenes in nematic liquid crystal (LC). Study of their spectral luminescent parameters in a planar oriented cell led to discovery of bands in the absorption spectra at 1300 and 1700 nm. In our assumption, they correspond to transitions between van Hove singularities (VHS) in electronic state densities. It gave us the opportunity to pioneer measurement of absorption dichroism in the suspensions of carbon nanoparticles and found existence of different polarizations at transitions, responsible for background absorption and absorption in the van Hove bands. The role of the photochemical factor in photodynamics of optical limiting on carbon nanoheterostructures is discussed.

This paper describes work in modeling the performance of multiwavelength bioaerosol sensors. In particular, results are presented on modeling the performance of the Biological Agent Sensor Testbed (BAST), which employs LED UV sources at 280 and 340 nm. A previously developed catalog of Excitation/Emission Matrix (EEM) data for bioagents and interferents is used to determine fluorescence scattering for a specified particle mixture. These particle mixtures were applied to the model in order to assess discrimination performance. An initial comparison of simulated and measured BAST data is presented. This work was sponsored by DARPA under the Semiconductor Ultraviolet Optical Sources (SUVOS) program.

We present initial results of a measurement system designed for detecting the fluorescence spectrum of individual particles of biological warfare agent (BWA). A compact optical parametric oscillator with intracavity sum-frequency mixing and a commercial Nitrogen gas laser was used as excitation sources to generate 293 nm or 337 nm UV laser irradiation. The pulsed lasers and a photomultiplier tube (PMT) array based spectrometer were triggered by a red laser-diode and a PMT detector that sensed the presence of a particle typical of size 5-20 μm in diameter. The spectral detection part of the system consisted of a grating and a PMT array with 32 channels, which measured fluorescence in the wavelength from 280 nm to 800 nm. The detector system was used to demonstrate the measurement of laser induced fluorescence spectra of individual BWA simulant particles by excitation of single UV laser pulses. The spectrum obtained by averaging spectra from several BWA aerosol simulant particles were found generally similar, but not identical, to the fluorescence spectrum obtained from water solutions containing the same particles dissolved.

Laser diodes and light-emitting diodes capable of continuous sub-300 nm radiation emission will ultimately represent optimal excitation sources for compact and fieldable bio-aerosol monitors. However, until such devices are routinely available and whilst solid-state UV lasers remain relatively expensive, other low-cost sources of UV can offer advantages. This paper describes one such prototype that employs compact xenon discharge UV sources to excite intrinsic fluorescence from individual particles within an ambient aerosol sample. The prototype monitor samples ambient air via a laminar sheathed-flow arrangement such that particles within the sample flow column are rendered in single file as they intersect the beam from a continuous-wave 660nm diode laser. Each individual particle produces a scattered light signal from which an estimate of particle size (down to ~1 um) may be derived. This same signal also initiates the sequential firing (~10 us apart) of two xenon sources which irradiate the particle with UV pulses centred upon ~280 nm and ~370 nm wavelength, optimal for excitation of bio-fluorophores tryptophan and NADH respectively. For each excitation wavelength, fluorescence is detected across two bands embracing the peak emissions of the same bio-fluorophores. Thus, for each particle, a 2-dimensional fluorescence excitation-emission matrix is recorded together with an estimate of particle size. Current measurement rates are up to ~125 particles/s (limited by the xenon recharge time), corresponding to all particles for concentrations up to ~2 x 10⁴ particles/l. Developments to increase this to ~500 particles/s are in hand. Analysis of results from aerosols of E.coli, BG spores, and a variety of non-biological materials are given.

AirSentinel^® is a new low cost, compact ultraviolet-based light induced fluorescence (UV-LIF) bio-aerosol threat detection trigger. Earlier UV-LIF triggers, for example, FLAPS, BARTS, BAWS, Bioni, and BioLert, have used UV laser sources to induce fluorescence of biological aerosols. Two recent developments from the DARPA MTO SUVOS program, BAST and TAC-BIO, use UV LEDs for the same purpose, thereby broadening the term UV-LIF to mean laser or LED induced autofluorescence. All of these earlier triggers interrogate aerosols on a particle-by-particle basis on- the-fly. The major trade-off for these instruments is cost, size, and complexity versus counting efficiency (probability of detection) with the lower size end of the respirable range being most difficult to detect. AirSentinel^® employs a different approach to UV-LIF detection: aerosol concentration by collection on a surface, surface interrogation, and surface rejuvenation prior to repeated concentration and interrogation cycles. Aerosol particle concentration via impaction on a surface addresses the issue of small particle counting efficiency since the fluorescence from the sum of the particles is the sum of the fluorescence signals from the collected particles, typically hundreds or thousands in number. Surface interrogation for a LIF signal is accomplished by illumination with a 280 nm and/or a 365 nm LED. As expected, test results show better relative detection performance using 280 nm excitation LEDs for bio-toxin simulants and somewhat better performance at 365 nm for standard Bacillus globigii spore targets. AirSentinel^® beta technology is currently in long term testing in a number of public and other government buildings.

Protein based infections such as prion diseases have lately attracted a large amount of interest, primarily due to the Mad Cow Epidemic in Great Britain, and the increase of Alzheimer's disease and related diseases in the ageing Western society. Infective proteins are very stable and almost untraceable prior to infection making them ideal as biological weapons. Particularly if the used agent is of human origin, the immunoresponse can be avoided, leaving no trace of the infectious agent. The transient nature of infectious oligomeric intermediates of misfolded proteins or peptide fragments that later matures into fibrillar aggregates makes them hard to study, and methods to detect and study these species are sparse. There exist a number of fluorescent probes that bind specifically to protein amyloidic structures. Thioflavins (ThT, ThS), Congo and Nile red, 4-(dicyanovinyl)-julolidine (DCVJ), as well as derivatives amino-8-naphtalene sulphonate (ANS, Bis-ANS) which are known to bind to the fibrillar or pre-fibrillar states with dissociation constants of typically 1 - 20 μM. Here, transthyretin (TTR), insulin and lysozyme were used as model proteins to detect different amyloid precursor states for diseases such as senile systemic amyloidosis, familial amyloidotic polyneuropathy (FAP) and iatrogenic amyloidosis. Specifically, the probes were employed in static assays to characterize protofibrillar and mature amyloid fibrillar states using steady state and time-resolved fluorescence techniques. Particularly, we investigate and report on the possibility to detect protofibrillar states at low concentration levels using modern fluorescence array detector systems in conjunction with lasers operating in the blue or ultraviolett wavelengths as excitation source. Results of ANS, ThT and a ThT analogue (abbreviated ThC) are discussed.

The synthesis, spectroscopic characterization and fluorescence quenching efficiency of a polymer (PSt-NI) and a low molecular weight molecule (NI) containing the 4-(N, N disubstituted)amino-N-2,5ditertiobutylphenyl-1,8-naphthalimide chromophore are reported. Similar spectroscopic properties of thin films and solutions are observed. This is consistent with the absence of interactions between polymer side chains. The absorption and fluorescence spectra of PSt-NI studied in various solvents of different polarity are compared to the corresponding spectra of NI. The longest wavelength absorption of PSt-NI and NI is characterized by a band with a maximum wavelength around 410 nm. The peak position is sensitive to the polarity of the solvent, which is in agreement with the charge transfer character of the transition. The fluorescence spectrum of PSt-NI shows a maximum emission in chloroform at 515 nm and is red shifted compared to those of NI. Fluorescence lifetimes of PSt-NI and NI are measured in presence and absence of 2,4-dinitrotoluene (DNT) and the results are interpreted via the Stern-Volmer analysis. In solution, the fluorescence quenching of NI is purely collisional, whereas both dynamic and static quenching are observed with PSt-NI Upon 1 minute exposure to DNT vapor, it was shown that a 5 nm thick film of PSt-NI exhibited a 45% drop in its fluorescence intensity, which makes this polymer very attractive for sensing applications.

A fibre optic platform has been fabricated for the field deployment of evanescent wave cavity ring-down spectroscopy with an absorbance sensitivity of 5 ppm. An optical cavity is fabricated by depositing high-reflectivity mirrors onto each end of the fibre and the evanescent field is exposed to the sample in a tapered region of the cavity. The decay time, τ, is dominated by the propagation loss of the radiation in the fibre optic and the loss of the tapered region. The multi-pass configuration can detect molecules adsorbing to the surface of the tapered region if they absorb radiation at the wavelength of the laser. An indicator molecule has been tethered to the glass surface to produce a colour change in response to the bulk pH producing an optical pH sensor with a sensitivity of 0.01 pH units. The fibre cavities have potential to form an optical sensor network to detect target molecules with presumptive detection on functionalised fibre surfaces.

Standoff detection, identification and quantification of chemicals in the gaseous state 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 a novel instrument that can not only provide an early warning for chemical agents and toxic chemicals, but also one that provides a "Chemical Map" of the field of view and is man portable. 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 boresighted 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.

High resolution non-invasive 3D imaging devices are required to detect pathogenic microorganisms such as Anthrax spores, bacteria, viruses, fungi and chemical agents entering biological tissues such as the epidermis. Due to the low light penetration depth and the biodamage potential, ultraviolet light sources can not be employed to realize intratissue imaging of bio- and chemohazards. We report on the novel near infrared laser technology multiphoton tomography and the high resolution 4D imaging tool DermaInspect for non-invasive detection of intratissue agents and their influence on cellular metabolism based on multiphoton autofluorescence imaging (MAI) and second harmonic generation (SHG). Femtosecond laser pulses in the spectral range of 750 nm to 850 nm have been used to image in vivo human skin with subcellular spatial and picosecond temporal resolution. The non-linear induced autofluorescence of both, skin tissues and microorganisms, originates mainly from naturally endogenous fluorophores/protein structures like NAD(P)H, flavins, keratin, collagen, elastin, porphyrins and melanin. Bacteria emit in the blue/green spectral range due to NAD(P)H and flavoproteins and, in certain cases, in the red spectral range due to the biosynthesis of Zn-porphyrins, coproporphyrin and protoporphyrin. Collagen and exogenous non-centrosymmetric molecules can be detected by SHG signals. The system DermaInspect consists of a wavelength-tunable compact 80/90 MHz Ti:sapphire laser, a scan module with galvo scan mirrors, piezo-driven objective, fast photon detector and time-resolved single photon counting unit. It can be used to perform optical sectioning and 3D autofluorescence lifetime imaging (τ-mapping) with 1 μm spatial resolution and 270 ps temporal resolution. The parameter fluorescence lifetime depends on the type of fluorophore and its microenvironment and can be used to distinguish bio- and chemohazards from cellular background and to gain information for pathogen identification. The novel in vivo non-invasive imaging system offers the possibility to detect and to localize CB agents in tissues and to gain information on their impact on respiratory chain activity, cell division and metabolism. The system DermaInspect can also be used to detect food and water contamination.

Recently developed deep-UV light-emitting diodes (LEDs) are already used in prototype fluorescence sensors for detection of hazardous biological agents. However, increasing of the sensor ability of discrimination against common interferents requires further development of measurement technique. In particular, LED-based fluorescence lifetime measurements are to be considered as a technique supplementary to fluorescence spectral and excitation measurements. Here we report on application of UVTOP^® series deep-UV LEDs developed by Sensor Electronic Technology, Inc. for real-time measurements of fluorescence lifetime in the frequency domain. LEDs with the wavelengths of 280 nm (targeted to protein excitation) and 340 nm (for excitation of coenzymes NADH and flavins) were used. The output of the LEDs was harmonically modulated at frequencies up to 100 MHz and fluorescence lifetime on the nanosecond and subnanosecond scale was estimated by measuring the phase angle of the fluorescence signal in respect of the LED output. Dual-wavelength LED-based phase-resolved measurement technique was tested for discrimination of B. globigii against a variety of interferents such as diesel fuel, paper, cotton, dust, etc. We conclude that fluorescence phase measurements have potential to improve the discrimination ability of the "detect-to-warn" optical bioparticle sensors.

An aerosol deflection technique based on the single-shot UV-laser-induced fluorescence spectrum from a flowing particle is presented as a possible front-end bio-aerosol/hazardous-aerosol sensor/identifier. Cued by the fluorescence spectra, individual flowing bio-aerosol particles (1-10 um in diameter) have been successfully deflected from a stream of ambient aerosols. The electronics needed to compare the fluorescence spectrum of a particular particle with that of a pre-determined fluorescence spectrum are presented in some detail. The deflected particles, with and without going through a funnel for pulse aerodynamic localization (PAL), were collected onto a substrate for further analyses. To demonstrate how hazardous materials can be deflected, TbCl₃⋅6H₂O (a stimulant material for some chemical forms of Uranium Oxide) aerosol particles (2 μm in diameter) mixed with Arizona road dust was separated and deflected with our system.

The following paper describes the core technology of a real time optical biological agent detection system which has been developed from Biral's existing and proven ASAS^TM family of biological agent triggers and sensors. The sensor for the system has additional capabilities based on the introduction of a fluorescence sensor providing greater discrimination than previously available. The new sensor will be incorporated in the Integrated Sensor Management System (ISMS) which utilises complex real-time data tracking algorithms that simultaneously monitor the different aerosol characteristics. The system is capable of tracking and adjusting the sensor alert levels to take into account the constantly changing aerosol environment and thus significantly reduces the risk of false alarms. The use of two measurement systems, ASAS^TM and fluorescence in one sensor is a unique combination and a major advancement in the field of airborne biological agent detection and warning.