Biometric identification for forensic investigations and security continues to depend on classic fingerprinting in many instances. Existing techniques rely on either visible deposits or hidden (latent) fingerprints resulting from the transfer of residues from the finger to the surface. However, one of the limitations of classic fingerprinting, for use as forensic evidence, is in determining a time sequence of events. It is extremely difficult to establish a timeline, from fingerprint evidence alone. We present the capability of a new technique which images the electrical charge deposited by tribocharging when a finger contacts an electrically insulated surface. The method is applicable to insulating surfaces and has been tested on PVC, PTFE, Acetate and PVDF sheets. The latent electrostatic charge pattern is detected using a novel, microscopic, electric potential sensor. The sensor is capable of imaging static charge distributions non-invasively, with no discharging effect on the sample. We present data showing the decay of the charge image with time, over a period up to 14 days. This capability has two major implications. First this technique does not suffer from ambiguities caused by a history of old fingerprints and second it has the potential to allow the time sequence of recent charge fingerprint images to be determined.

In this contribution two analytical devices for the fast detection of security-relevant substances like narcotics and explosives are presented. One system is based on an ion trap mass spectrometer (ITMS) with single photon ionization (SPI). This soft ionization technique, unlike electron impact ionization (EI), reduces unwanted fragment ions in the mass spectra allowing the clear determination of characteristic (usually molecular) ions. Their enrichment in the ion trap and identification by tandem MS investigations (MS/MS) enables the detection of the target substances in complex matrices at low concentrations without time-consuming sample preparation. For SPI an electron beam pumped excimer light source of own fabrication (E-Lux) is used. The SPI-ITMS system was characterized by the analytical study of different drugs like cannabis, heroin, cocaine, amphetamines, and some precursors. Additionally, it was successfully tested on-site in a closed illegal drug laboratory, where low quantities of MDMA could be directly detected in samples from floors, walls and lab equipments. The second analytical system is based on an ion mobility (IM) spectrometer with resonant multiphoton ionization (REMPI). With the frequency quadrupled Nd:YAG laser (266 nm), used for ionization, a selective and sensitive detection of aromatic compounds is possible. By application of suited aromatic dopants, in addition, also non-aromatic polar compounds are accessible by ion molecule reactions like proton transfer or complex formation. Selected drug precursors could be successfully detected with this device as well, qualifying it to a lower-priced alternative or useful supplement of the SPI-ITMS system for security analysis.

There is a worldwide interest in developing a sensing system for the online detection and chemical identification of hazardous substances, especially in water and in air. Towards this goal we have developed an evanescent wave spectroscopy system based on a tunable CO2 on an IR detector and on thin AgBr flat waveguides, which were transparent in the mid-IR and served as sensing elements. Aqueous solutions of common pesticides (e.g. DDVP, Parathion, Diazinon) were placed on the waveguide and spectral absorption measurements were performed in the mid-IR. Using the results, we were able to detect these pesticides at concentrations as low as few ppm and distinguish between them. Such a system would be invaluable for homeland security applications.

Trace detection of energetic materials is a method to screen personnel, packages and other items for concealed explosives. It is likely, that a person who carries explosives will contaminate himself and the package with the explosive. We present first results on the development of a compact detector combining Pulsed Laser Fragmentation (PLF) with fragments detection. A passively q-switched UV microchip laser photofragments surface contaminations. The concentration ratio of the fragments NO and NO2 is a sufficient indicator for the presence of nitrogen-based explosives. For TNT, the results suggest, that a surface density as small as a few ng/cm2 can be reliably detected.

The reliable detection of concealed substances in sealed opaque plastic and coloured glass containers, with low falsealarm rate, is a problem in numerous areas of security. For example, in aviation security, there is no reliable methodology for alarm resolution of substances with high chemical specificity unless the substances are in optically transparent containers. We present a recently developed method called Spatially Offset Raman Spectroscopy (SORS) which enables the discrimination of the Raman spectrum of the content substance from the Raman spectrum of the container material with no prior knowledge of either, thereby allowing unambiguous identification of the container contents. The method is effective with coloured plastic containers that are several millimetres thick and which are not see-through to the eye and also for coloured glass bottles. Such cases do not typically yield to conventional backscatter Raman spectroscopy (or have poor false-alarm rates) since the content signal is often overwhelmed by the signal from the container, which may in addition have a strong interfering fluorescence background. SORS measurement can be performed in a few seconds by shining a laser light onto the container and then measuring the Raman signal at the excitation point but also at one or more offset positions. Each measurement has different relative orthogonal contributions from the container and contents Raman spectra, so that, with no prior knowledge, the pure spectra of both the container and contents can be extracted - either by scaled subtraction or via multivariate statistical methods. The content spectrum can then be compared to a reference library of pure materials to give a threat evaluation with a confidence level not compromised by interfering signals originating from the container wall. In this paper, we describe the methods and their optimization, and characterize their performance in practical screening applications. The study shows that there is frequently a well-defined optimum spatial offset that maximizes the signal to noise ratio (SNR) of the resultant SORS spectrum and that this optimum can vary greatly depending on content and container material. It is also shown for the first time that, for a fixed total acquisition time available, a very high fraction of this time should be spent acquiring the offset spectrum. For common samples, the best results were obtained where the offset measurement was acquired for 20x longer than the zero offset position.

Advances in the application of Quantum Cascade Lasers (QCL) to trace gas detection will be presented. The solution is real time (~1 μsec per scan), is insensitive to turbulence and vibration, and performs multiple measurements in one sweep. The QCL provides a large dynamic range, which is a linear response from ppt to % level. The concentration can be derived with excellent immunity from cross interference. Point sensing sensors developed by Cascade for home made and commercial explosives operate by monitoring key constituents in real time and matching this to a spatial event (i.e. sniffer device placed close to an object or person walking through portal (overt or covert). Programmable signature detection capability allows for detection of multiple chemical compounds along the most likely array of explosive chemical formulation. The advantages of configuration as "point sensing" or "stand off" will be discussed. In addition to explosives this method is highly applicable to the detection of mobile drugs labs through volatile chemical release.

The SDA (Spectral Dynamics Analysis) - method (method of THz spectrum dynamics analysis in THz range of frequencies) is used for the detection and identification of substances with similar THz Fourier spectra (such substances are named usually as the simulants) in the two- or three-component medium. This method allows us to obtain the unique 2D THz signature of the substance - the spectrogram- and to analyze the dynamics of many spectral lines of the THz signal, passed through or reflected from substance, by one set of its integral measurements simultaneously; even measurements are made on short-term intervals (less than 20 ps). For long-term intervals (100 ps and more) the SDA method gives an opportunity to define the relaxation time for excited energy levels of molecules. This information gives new opportunity to identify the substance because the relaxation time is different for molecules of different substances. The restoration of the signal by its integral values is made on the base of SVD - Single Value Decomposition - technique. We consider three examples for PTFE mixed with small content of the L-Tartaric Acid and the Sucrose in pellets. A concentration of these substances is about 5%-10%. Our investigations show that the spectrograms and dynamics of spectral lines of THz pulse passed through the pure PTFE differ from the spectrograms of the compound medium containing PTFE and the L-Tartaric Acid or the Sucrose or both these substances together. So, it is possible to detect the presence of a small amount of the additional substances in the sample even their THz Fourier spectra are practically identical. Therefore, the SDA method can be very effective for the defense and security applications and for quality control in pharmaceutical industry. We also show that in the case of substances-simulants the use of auto- and correlation functions has much worse resolvability in a comparison with the SDA method.

There is an ever-increasing need to be able to detect the presence of explosives, preferably from standoff distances of tens of meters. This paper presents an application of visible hyperspectral imaging using anomaly, polarization, and spectral identification approaches for the standoff detection (13 meters) of nitroaromatic explosives on realistic painted surfaces based upon the colorimetric differences between tetryl and TNT which are enhanced by solar irradiation.

Our experiments focused on monitoring the signal obtained from diffuse reflections of forward-generated coherent anti-Stokes Raman scattering (CARS), occurring in different samples, referred to as "backward-CARS" (B-CARS). The methodology of B-CARS was developed and the feasibility of using it as a spectroscopic tool for standoff detection of particles of explosives and related compounds studied. Signals of both the B-CARS and spontaneous Raman scattering under similar conditions were monitored to compare their sensitivities. In addition, the dependence of the B-CARS signal on the distance was measured at short ranges and the standoff detection capabilities of the method at long distances estimated. The measurements imply that B-CARS allows favorable detection as compared to Raman. However, an inherent drawback of the developed narrowband B-CARS method is the need to scan the Stokes beam frequency to monitor the different vibrational levels of the detected species. We therefore embarked on a broadband B-CARS method (patent pending) which is based on the application of a sub-ns ultra-broadband laser source for the Stokes beam and enables to monitor simultaneously a wide span of vibrational transitions of the detected species.

We present our work on stand-off Raman detection of explosives and related compounds. Our system employs 532 or 355 nm laser excitation wavelengths, operating at 10 Hz with a 4.4 ns pulse length and variable pulse energy (maximum 180 mJ/pulse at 532 nm and 120 mJ/pulse at 355 nm). The Raman scattered light is collected by a co-axially aligned 6" telescope and then transferred via a fiber optic cable and spectrograph to a fast gating iCCD camera capable of gating at 500 ps. We present results including the effect of different excitation wavelengths, showing that 355 nm excitation gives rise to significantly stronger stand-off Raman signals compared to that of 532 nm. We also show the effect of appropriate detector gating widths for discrimination of ambient light and the reduction of high background signals in the obtained Raman spectra. Our system can be used to identify explosives and their precursors in both bulk and trace forms such as RDX and PETN in the low mg range and TNT in the 700 μg range at a distance of 20 m, as well as detection of a 1% or greater H₂O₂ solution at a distance of 6.3 m.

This paper will demonstrate that near infrared (NIR) signals at wavelengths in the range 0.9 to 2.5 microns can be used for personal screening applications. At these wavelengths, there is sufficient spectral information to provide chemical identification, while still providing transmission through many types of common clothing materials. Thus, chemical identification in diffuse reflection is possible. Initial measurements on selected clothing materials have indicated that there is sufficient transmission to allow NIR spectra from concealed chemicals to be collected. The effect of the clothing material on the observed spectra has also been quantified. The clothing materials ranged from cotton to man-made fibres. Spectra have been collected at stand-off distances of several metres or more, using a suitable lens system and an NIR spectrometer. The optics required to achieve this will be described, and some spectra from chemicals hidden behind clothing will be presented. The further steps necessary to provide correct identification of chemicals such as ammonium nitrate in granular form will also be given, involving signal analysis methods. A set of spectra will be shown that have been collected and analysed, for a wide range of clothing fabric materials, indicating that the technique could have wide application to personal screening situations.

The Nerve gases are persistent gases that appear as very challenging menace in homeland security scenarios, due to the low pressure vapor at ambient temperature, and the very low lethal concentrations. A novel approach to the detection and identification of these very hazardous volatile compounds in large areas such as airports, underground stations, big events arenas, aimed to a high selectivity (Low false alarm probability), has been explored under the SENSEFIB Corporate Project of Finmeccanica S.p.A. The technical demonstrator under development within the Project is presented. It is based on distributed line sensors performing infrared absorption measurements to reveal even trace amounts of target compounds from the retrieval of their spectral fingerprint. The line sensor is essentially constituted by a widely tunable external cavity quantum cascade laser (EC-QCL), coupled to IR thermoelectrically cooled MCT fast detectors by means of a infrared hollow core fibers (HCF). The air is sampled through several micro-holes along the HCF, by means of a micropump, while the infrared radiation travels inside the fiber from the source to the detector, that are optically coupled with the opposite apertures of the HCF. The architecture of the sensor and its principle of operation, in order to cover large areas with a few line sensors instead of with a grid of many point sensors, are illustrated. The sensor is designed to use the HCF as an absorption cell, exploiting long path length and very small volume, (e.g fast response), at the same time. Furthermore the distributed sensor allows to cover large areas and/or not easily accessible locations, like air ducts, with a single line sensor by extending the HCF for several tens of meters. The main components implemented in the sensor are described, in particular: the EC-QCL source to span the spectral range of wavelength between 9.15um and 9.85um; and the hollow core fiber, exhibiting a suitably low optical loss in this spectral range (<1dB/m). Also, the characteristics of detectors and associated electronics for signal processing and data acquisition are discussed. Main results from preliminary measurements carried out are also presented.

The DLR laser test range at Lampoldshausen allows for optical measurements under daylight conditions at distances up to 130 m. This infrastructure is very suitable for the development of standoff detection systems for biological, chemical and explosive hazardous substances. In a first step, laser-induced breakdown spectroscopy (LIBS) has been introduced to this test site. A basic LIBS setup and first LIBS spectra of selected samples are presented. A Nd:YAG laser beam was focused by a Cassegrain type telescope onto different samples at distances exceeding 50 m. The light of the generated plasma plume was collected by a Newtonian telescope and analyzed by a gated broadband CCD-spectrometer system. The Nd:YAG laser yields pulse energies up to 800 mJ at a wavelength of 1064 nm and a pulse width of 8 ns. Optionally the second and third harmonics can be extracted. LIBS spectra from 10 nm layers of gold on a silicon wafer were recorded. In addition, LIBS spectra from black powder were measured and compared to the spectrum of potassium nitrate, which is a main component of black powder and shows very characteristic emission lines. LIBS spectra of the above samples have also been acquired with an excitation laser wavelength in the eye-safe region. Recorded spectra are measured as a function of the laser wavelength, pulse energy and distance to the target substance.

A standoff bioaerosol sensor based on intensified range-gated spectrometric detection of Laser Induced Fluorescence was used to spectrally characterize bioaerosol simulants during in-chamber and open-air releases at Suffield, Canada, in August 2008 from a standoff position. In total, 42 in-chamber Bacillus atrophaeus (formerly Bacillus subtilis var globigii; BG) cloud and 27 open-air releases of either BG, Pantoea agglomerans (formerly Erwinia herbicola; EH), MS2 and ovalbumin (OV) were generated. The clouds were refereed by different point sensors including Aerodynamic Particle Sizer (APS) and slit or impingers samplers. The APS monitored the particle size distribution and concentration and the samplers characterized the viable portion of the cloud. The extracted spectral signatures show robustness to different degree. The correlation assessment showed good results in most cases where the LIF signal to noise ratio was significant. The sensor 4σ sensitivity was evaluated to 1 300, 600, 100 and 30 ppl for BG, OV, MS2 and EH respectively. Correlation results are presented by plotting the SINBAHD metric versus the corresponding particle concentration, in which case, the obtained slope is proportional to the material fluorescence cross-section. The different acquired signal is hence compared in terms of their fluorescence cross-section additionally to their spectral characteristics.

An innovative Active Laser Imaging (ALI) vision system is presented. We report the experimental data of a short range ALI able to achieve range measurements and to recognize people up to 5 km away, according to Johnson's criterion. We also report the simulation data of a long range ALI working in excess of 10 km. The ALI uses a laser to illuminate an area and a telescope to collect the scattered light into an InGaAs camera. The laser has been developed internally; it is an eye safe class I pulsed laser operating at about 1.5 μm; its divergence and direction are changed according to the scene and environmental conditions. The ALI can be used in active mode, with the laser on, or in passive mode using external short wave infrared (SWIR) illumination sources. The data collected by the ALI and a thermal IR camera show the ability of ALI to look across glasses and to read writings and the impossibility of thermal IR camera to do the same. We describe the software models developed to emulate the ALI, the scenes, and the environmental conditions. The models have been validated by experimental data and used to design the ALI.

Scene understanding (SU) is a high priority in many areas. Currently many SU algorithms are developed using imagery which is often captured in constant, well lit environments with low clutter and not affected by noise, compression or bandwidth artefacts. The initial research addressed how SU can assist automatic identification, semantic tagging and tracking of an object in a scene. However, it became apparent that current algorithms and software are unable to successfully process typical military imagery. Consequently, research was undertaken to assess how well current SU algorithms process imagery captured by a variety of typical military imagers. The imagery was chosen such that it covered a variety of scenarios and applied to a range of algorithms. It became apparent that the many algorithms experienced difficulties in processing the typical military imagery or had other drawbacks such as computational cost, which impacts on military utility. The National Imagery Interpretability Rating Scale (NIIRS) was used in order to help explain the general quality of military imagery and the analysis tasks which are expected to be carried out on it.

Infrared systems are key to providing enhanced capability to military forces such as automatic control of threats and prevention from air, naval and ground attacks. Key requirements for such a system to produce operational benefits are real-time processing as well as high efficiency in terms of detection and false alarm rate. These are serious issues since the system must deal with a large number of objects and categories to be recognized (small vehicles, armored vehicles, planes, buildings, etc.). Statistical learning based algorithms are promising candidates to meet these requirements when using selected discriminant features and real-time implementation. This paper proposes a new decision architecture benefiting from recent advances in machine learning by using an effective method for level set estimation. While building decision function, the proposed approach performs variable selection based on a discriminative criterion. Moreover, the use of level set makes it possible to manage rejection of unknown or ambiguous objects thus preserving the false alarm rate. Experimental evidences reported on real world infrared images demonstrate the validity of our approach.

We propose a space variant Maximum Average Correlation Height (MACH) filter which can be locally modified depending upon its position in the input frame. This can be used to detect targets in an environment from varying ranges and in unpredictable weather conditions using thermal images. It enables adaptation of the filter dependant on background heat signature variances and also enables the normalization of the filter energy levels. The kernel can be normalized to remove a non-uniform brightness distribution if this occurs in different regions of the image. The main constraint in this implementation is the dependence on computational ability of the system. This can be minimized with the recent advances in optical correlators using scanning holographic memory, as proposed by Birch et al. [1] In this paper we describe the discrimination abilities of the MACH filter against background heat signature variances and tolerance to changes in scale and calculate the improvement in detection capabilities with the introduction of a nonlinearity. We propose a security detection system which exhibits a joint process where human and an automated pattern recognition system contribute to the overall solution for the detection of pre-defined targets.

Hyperspectral imaging (HSI) systems have been used widely in many applications including the defence and military for target acquisitions. However, the effectiveness of HSI can be greatly hampered by illumination artifacts such as shadowing or bidirectional reflection differentials issues. This paper addresses how shadows in the HSI, particularly for the imageries that are taken in the indoor scenarios, can be partially mitigated through a diffused irradiance compensation (DIC) methodology. The effectiveness of the proposed work is then compared with the widely adopted pixel normalisation and band ratioing methods. The performances of all these processing methods have been assessed using Maximum Likelihood Classifier. The result has shown an almost 70% improvement in classification accuracy after the raw DN data is translated into 'apparent' reflectance using simple ELM based method, and the classification accuracy after spectral normalisation is ~26% worse than without normalization. When the proposed diffused irradiance compensation (DIC) is combined with other band ratioing techniques, the classification accuracy is found to be improved by ~7% over that processed by the ELM method for the entire scene. There are about 32% of shadowed pixels in this data set and hence 7% of improvement represents a significant improvement on the shadow mitigation.

The Image Library for Intelligent Detection Systems (i-LIDS) is the United Kingdom government's benchmark for Video Analytics (VA) systems. There are currently 5 different scenario based datasets available. A new suite of datasets is under development, intended to assess VA performance working with imagery obtained under Near Infra Red (NIR) illumination conditions and from thermal imagers (infra red cameras). This paper describes the datasets that are under construction. The datasets should be publically available in late 2010.

This paper reports on the enhancement of biologically-inspired machine vision through a rotation invariance mechanism. Research over the years has suggested that rotation invariance is one of the fundamental generic elements of object constancy, a known generic visual ability of the human brain. Cortex-like vision unlike conventional pixel based machine vision is achieved by mimicking neuromorphic mechanisms of the primates' brain. In this preliminary study, rotation invariance is implemented through histograms from Gabor features of an object. The performance of rotation invariance in the neuromorphic algorithm is assessed by the classification accuracies of a test data set which consists of image objects in five different orientations. It is found that a much more consistent classification result over these five different oriented data sets has been achieved by the integrated rotation invariance neuromorphic algorithm compared to the one without. In addition, the issue of varying aspect ratios of input images to these models is also addressed, in an attempt to create a robust algorithm against a wider variability of input data. The extension of the present achievement is to improve the recognition accuracies while incorporating it to a series of different real-world scenarios which would challenge the approach accordingly.

Iris recognition is the most reliable method in personal identification. With the increase of real applications based on iris recognition, liveness detection is becoming more and more important. Here we proposed a liveness iris detection method based on the eye's optical features. With the help of designing special imaging and infrared illumination module and image analysis, we can implement the detection. The methods include finding the change of iris texture and light spot under different waveband and position of the infrared illumination, calculating the difference of the reflection property in different iris parts. We combine the methods and get the fusion results as the criteria. Experimental results show that this method can help the system distinguish the real iris and traditional kinds of fake irises since it combines the optical features of the real iris.

The SFS technology has already proved its analytical capabilities in a variety of industrial and environmental tasks. Recently it has been introduced for forensic applications. The key features of the SFS method - measuring a 3-dimensional spectrum of fluorescence of the sample (intensity versus excitation and emission wavelengths) with following recognition of specific spectral patterns of SFS responsible for individual drugs - provide an effective tool for the analysis of untreated seized samples, without any separation of the substance of interest from its mixture with accompanying cutting agents and diluents as a preparatory step. In such approach the chemical analysis of the sample is substituted by the analysis of SFS matrix visualized as an optical image. The SFS technology of drug detection is realized by NarTest® NTX2000 analyzer, compact device intended to measure suspicious samples in liquid, solid and powder forms. It simplifies the detection process due to fully automated procedures of SFS measuring and integrated expert system for recognition of spectral patterns. Presently the expert system of NTX2000 is able to detect marijuana, cocaine, heroin, MDMA, amphetamine and methamphetamine with the detection limit down to 5% of the drug concentration in various mixtures. The numerous tests with street samples confirmed that the use of SFS method provides reliable results with high sensitivity and selectivity for identification of drugs of abuse. More than 3000 street samples of the aforesaid drugs were analyzed with NTX2000 during validation process, and the correspondence of SFS results and conclusions of standard forensic analyses with GC/MS techniques was in 99.4% cases.

The chronological order of creation of crossing lines scratched into a copper surface was determined using 3D profiles measured with SWLI and CM. As the methods used are based only on the deformations of the surface and since the imaging techniques can be used for different materials, the proposed methods are potentially effective also on other materials. Determining the chronological order of orthogonally crossing lines is studied in forensic science. The order of creation of such lines allows in some cases determination of the history of an object without comparing it to other objects.. Methods based on two dimensional (2D) imaging have been used for this task, but such methods are ineffective if the lines are made with a similar tool. We apply Scanning White Light Interferometry (SWLI) and Confocal Microscopy (CM) to study crossing lines on a copper surface scratched with a scratching device. Both SWLI and CM quantitatively measure the 3D surface profiles with sufficient accuracy for forensic applications. 3D image processing allows removing unimportant features, such as surface form and roughness, as well as measurement noise from the measured profiles. Separating inherent features in the crossing area, from other surface characteristics allows one to determine the sequence of creation of the lines even on a rough and wavy surface.

In article a digital system for high resolution infrared camera control and image processing is described. The camera is built with use of bolometric focal plane array of size 640 by 480 detectors. Single detector in array has size of 25 μm and can detect incident radiation from the spectral range of 8÷12 μm thanks to the special filter installed in specially designed entrance window. The most important tasks of infrared image processing system are array readout and correction of detectors offset and responsivity variations. The next tasks of the system are conversion of analog voltage signals from microbolometers in array to digital form and then composition of a thermal image. Microbolometer array needs to be controlled via several signals. The signal generator for readout circuit is capable of changing various timing parameters like frame rate or integration time of the detector array. The changes in these parameters can be done via special set of memory mapped registers. The infrared data received from detector array is transferred via data bus to modules performing image processing, for example techniques for image enhancement. Image processing algorithms necessary for infrared image generation are nonuniformity correction, bad pixel replacement and radiometric calibration. Optionally an additional image processing techniques can be performed like edge enhancement, dynamic range compression or object identification. The elaborated architecture of the system allowed easy change of parameters of the system and to adopt many new algorithms without significant hardware changes. Scientific work funded from science fund for years 2009-2011 as a development project.

The paper presents the concept of fiber optic sensor system for human psycho-physical activity detection. A fiber optic sensor that utilizes optical phase interferometry or intensity in modalmetric to monitor a patient's vital signs such as respiration cardiac activity, blood pressure and body's physical movements. The sensor, which is non-invasive, comprises an optical fiber interferometer that includes an optical fiber proximately situated to the patient so that time varying acusto-mechanical signals from the patient are coupled into the optical fiber. The system can be implemented in embodiments ranging form a low cost in-home to a high end product for in hospital use.

A multi-channel optical microchip sensor system suitable for real-time, label-free detection of a wide range of biological agents is presented. SpectroSens^TM chips containing multiple high-precision planar Bragg gratings are exploited as lowcost, robust refractive index sensors. Sensitivity to biological agents is conferred by functionalising individual sensing regions with different antibodies selected against numerous targets of interest. Antigen binding to the surfaceimmobilised antibodies results in localised changes in refractive index; upon laser-induced interrogation of the sensing region via optical fibres, these antibody-antigen interactions manifest as increases in wavelength of light reflected from the sensor chip. Real-time detection of multiple biological agents including bacterial cells/spores, viruses and toxins has been demonstrated. Further improvements to sensor performance including physical and chemical methods are also investigated. This multi-analyte capability highlights the potential use of this sensing technology in applications ranging from bio-hazard detection for defence purposes to point-of-care clinical diagnostics.

Fibre loop cavity ring-down spectroscopy (FLCRDS) is a relatively new technique, which extends the more commonly used two-mirror cavity ring-down spectroscopy (CRDS) technique to measurements of optical absorption by minute liquid sample volumes. In this paper, loops of 50 μm-core-diameter multimode optical fibre were used to carry out both direct and evanescent wave FLCRDS measurements at 532 nm. The sensitivity of each technique was established by making measurements on a common dye, rhodamine 6G; detection limits were found to be in the micromolar range for aqueous rhodamine, in a sample volume of only a few picolitres. In this case, evanescent wave FLCRDS was found to be more sensitive than direct absorption. Functionalisation of the silica taper used for evanescent absorption measurements allows for binding measurements to be carried out. We report the results of preliminary proof-of-concept measurements on the binding of streptavidin to a biotinylated taper.

We present, in a first part, the complete elaboration process of AgGaS₂ to obtain 4×4×15 mm³ slabs and the first results on ZnGeP₂. A two zone oven was designed for the chemical synthesis and the vertical Bridgman method was chosen for the growth. These slabs were tested on optical benches to produce mid-IR laser emissions from near IR sources: results on Difference Frequency Generation are presented in a second part.

The lanthanide compounds containing unsymmetrical β-diketone with [2.2]paracyclophane moiety in particular the europium complex with three [1-(4-[2.2]paracyclophanyl)]-3-phenylpropane-1,3-dione and 1,10-phenanthroline has been synthesized for the first time. The optical properties of [2.2]paracyclophane-derived ligands (symmetrical β-diketones and their respective N-phenylimines) as well as those of the europium complex were studied by UV-visible and luminescence spectroscopy. The diastereomers (racemic chiral, (R*,R*)- and achiral meso, (R,S)-) of the β-diketones and their respective N-phenylimines exhibit quite identical absorption spectra with intense broad band centered at 360 and 380 nm, respectively. The designed blue-emitting unsymmetrical β-diketone acts as a very efficient sensitizer of the EuIII emission and does so in the near-UV region. The introduction of [2.2]paracyclophane moiety in the β-diketones allows to expand the excitation wavelength of the lanthanide complex up to 500 nm and to obtain the relatively high overall quantum yield for the europium ion.

Two of the key challenges in the realisation of focal plane arrays based on type-II InAs/GaSb superlattices (T2SL) are the difficulty in achieving a good sidewall profile and the increased dominance of surface leakage current as the device dimensions shrink. We report the electrical and morphological results of test pixels for mid-wave infrared T2SL photodiodes etched using a Cl₂/Ar based inductively coupled plasma reactive ion etching (ICP-RIE) process and passivated using SU-8 epoxy photoresist. The etch rate and sidewall surface morphology of GaSb, InAs, and InAs/GaSb T2SL materials are compared after dry etching under the same conditions, leading to the determination of an optimal etch rate. The effect of surface treatment using selected wet chemical etchants before passivation on the surface leakage current is presented. Limitations of the dry etching recipe and further improvement of the sidewall verticality and smoothness are also discussed. Good sidewall profiles and bulk-limited dark currents are demonstrated for T2SL photodiodes etched to depths between 1.5 and 3.5 μm with a pitch size down to 12 μm.

A high output power, eye-safe, LIDAR transmitter based on a KTA optical parametric oscillator (OPO) was demonstrated. The OPO was based on a two crystal, NCPM, KTA ring cavity which was doubly resonant. A 7ns, 30Hz, flashlamp-pumped, Q-switched Nd:YAG laser was injection seeded and used to pump the OPO. The OPO converted the 1064 nm pump beam into a 1533 nm signal wave and 3475 nm idler wave. In addition to demonstrating a high power OPO system, we investigated the effects of seeding the pump laser on the OPO's conversion efficiency, oscillation threshold, maximum signal power, and beam quality. The power conversion efficiency between the signal and the injection seeded pump was 22% with an oscillation threshold of 104 MW/cm² (500 mJ) and a maximum signal power of 6.44 W (215 mJ). The power conversion efficiency between the signal and the unseeded pump was 24% with an oscillation threshold of 77 MW/cm² (367mJ) and a maximum signal power of 7 W (233 mJ). The beam quality of the signal beam was produced an M² =15. When the pump laser was seeded, the full angle divergence improved by nearly a factor of five.

In this work we study optical response of noble metal nanoparticles and report how it may be controllably varied over a wide range of wavelengths. Altering the particle shape and materials we investigate the surface plasmon resonances of nanostars. To design novel nanostructures possessing diverse optical properties we assemble several plasmonic materials into a single nanoparticle. With numerical simulation tool based on the spectral boundary integral equation method we investigate far-field and near-field characteristics of a variety of metal, metal-dielectric and bimetal nanostructures to be used in a range of applications from disease diagnostics through to the identification of contraband.

The extreme properties of diamond make it an exceptional material for a range of demanding optical applications. However, the use of single crystal diamond in lasers has been limited by the availability of suitably-sized crystals with low absorption, and the relatively high levels of strain-related birefringence present. We present recent progress in CVD diamond synthesis which addresses these properties, and show how this new high quality, engineered diamond is enabling novel laser technologies such as mid-IR semiconductor disk lasers and high efficiency diamond Raman lasers.

Two different position sensitive devices for large-area detection of light points and objects are presented. The core of the system consists of a luminescent foil, where impinging laser light is absorbed and the fluorescence light is coupled out via attached silicon photodiodes. Due to a direct relation between the signal amplitude and the distance to the photodiodes, this detector can be used for pinpointing laser spots over large areas. When fixing small stripes of the detector inside a rectangular frame, the foil can be used for object tracing over large-areas as well.

In this paper we present a series of side-chain polymers bearing original azo-moieties, namely: poly(methacrylate)s and poly(maleimide-styrene)s; designed for nonlinear optics (NLO). The different classes of azopolymers are discussed comparatively to one another from the point of view of: solubility, molar weights, glass transition temperatures & thermal stability, chromophore contents, and as well as from the point of view of their third-nonlinear response. The third-order nonlinear absorptive and refractive effect of the polymers containing different substituted azobenzene chromophores were investigated by the Z-scan technique. The effect of substituents on the azobenzene group and the composition of the polymer chain were investigated by UV-Vis spectroscopy.

The Copper(I)-catalyzed Azide-Alkyne Cycloaddition (CuAAC) has been investigated as a versatile synthetic pathway to graft highly chemically sensitive "push-pull" chromophores onto a polymer backbone. We demonstrate that the CuAAC is highly efficient in mild conditions, chemioselective and is a powerful tool to design new powerful organic NLO side-chain copolymers.

An attempt is made to study the carrier contribution to the elastic constants in QWs and QWWs of II-V , IV-VI, III-V, ternary and quaternary types of optoelectronic compounds. It has been found, taking QWs and QWWs of CdGeAs2, InAs, Hg1-xCdxTe, In1-xGaxAsyP1-y lattice matched to InP, CdS and PbSe as examples for numerical computations that the second and third order elastic constants increase with increasing carrier degeneracy and decreasing film thickness respectively in various oscillatory manners emphasizing the influence of dimensional quantizations and the energy band constants in different cases. An experimental method of determining the said contribution in QWs and QWWs having arbitrary dispersion laws has also been suggested and the present simplified analysis is in agreement with the suggested relationship. The well-known results for widegap materials having nondegenerate electron concentration have also been obtained as special cases of our generalized theory under certain limiting conditions.

Effective correlation between photoconductive and photorefractive characteristics of fullerene-, quantum dots-, and nanotubes-doped organic thin films based on polyimide, pyridine, etc. have been studied. The increase of the charge carrier mobility has been established. The nonlinear refraction and cubic nonlinearity have been investigated at wavelength of 532 nm via four-wave mixing technique using Raman-Nath diffraction regime. The correlation between photoconductive and nonlinear optical parameters has been revealed. The nanostructured materials can be proposed for different area of nano- and microelectronic applications.

Colored micron-sized methyl methacrylate particles have been obtained by dispersion polymerization of methyl methacrylate and an azo-monomer in the presence of vinyl silane oxazoline macromonomer used as stabilizer. The polymerizable dye has a methacryloyl group for copolymerization and suitable azobenzene moiety to improve the solubility in the solvent. The particles showed a spherical morphology and large size distribution, features which were appreciated by scanning electron microscopy. The azo-dye could be covalently incorporated up to 4 wt% in the particles. The thermal properties of the particles were investigated by simultaneous DSC-TGA analysis. The particles showed clear Tgs at 128 °C and thermal stability up to 292 °C. The copolymer's chemical structures were confirmed by 1H-NMR and FT-IR spectroscopy and their average molecular weights were evaluated by SEC.