This PDF file contains the front matter associated with SPIE Proceedings Volume 8542, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

For use in the development of synthetic environment models, the Swedish Defence Research Agency (FOI) bought two laser scanners in the beginning of this millennium, one from the Austrian company Riegl and one from the Canadian Optech. This was the start for over a decade of use of commercial laser range sensors at FOI. The laser scanners have so far been used for different applications such as point cloud algorithm development (detection, classification and reconnaissance of targets), phenomenology studies, reflectance measurements and environment and ground truth measurements. This paper presents different laser scanner technologies (pulsed Time of Flight, Continues Wave (CW), Flash and distributed light) and compare advantages and limitations of the technologies. The paper also include some examples of the use of laser scanning in applications and presents methods for laser range sensors performance evaluation used and developed at FOI.

Homogeneous and speckle-free laser illumination devices are the key technology for high resolution active imaging and range-gated viewing systems. At ISL, a waveguide technology was developed to effectively reduce laser speckle of solid-state laser sources by a spatial or angular diversity approach, respectively. Further, a distant scene is illuminated with a homogeneous rectangular top-hat profile. In the present publication we give a theoretical description of the waveguide laser illumination devices and present results from ray tracing simulations and experimental investigation.

In the present publication we introduce coding sequences with quasi-ambiguous combinations for 3D imaging. With this extended imaging method it is possible to apply 15 combinations of gray level for the coding of range- gates in 3 images. Nevertheless, it is demonstrated that a maximum number of only 13 combinations can be connected to sequences. In this publication, the impact of quasi-ambiguous sequences on the 3D depth mapping capabilities is studied and discussed. An analysis of simulated image sequences was performed with different portion of noise. At low noise levels it is shown that the quasi-ambiguous coding sequences can enlarge the depth mapping range. But misinterpretation of data reduces dramatically the range accuracy at high noise levels. Therefore, 3D imaging profits from the application of quasi-ambiguous sequences only at low noise level.

Primarily, a Gated-Viewing (GV) system provides range gated imagery. By increasing the camera delay time from frame to frame, a so-called sliding gates sequence is obtained by which 3-D reconstruction is possible. Scintillation caused by atmospheric turbulence degrades each Gated-Viewing image and thus, the range accuracy that can be achieved with the sliding gates method. By averaging a certain number of images per range, this degradation can be reduced. In this paper we have studied the influence of the number of averaged images on the resulting range accuracy. Therefore, we have combined the Intevac Gated-Viewing detector M506 with a pulsed 1.57 μm laser source. The maximal laser pulse energy was 65 mJ. The target was a 1-m²-plate at a distance of 500 m. The plate was laminated with a Spectralon layer having Lambertian reflection behavior with a homogeneous reflectance of 93 %. It was orientated diagonally to the line of sight of the sensor in order to provide a depth scenario. We have considered different combinations of the four parameters »detector binning mode« (1x1, 2x2), »optics« (f = 250 mm, f/2.1; f = 500 mm, f/3.3; f = 2032 mm, f/10), »gate length« (13.5 m, 23.25 m, 33 m) and »signal-to-noise ratio« (SNR) (1 dB, 2 dB,…, 9 dB). For each considered set of parameters, a sliding gates sequence of the target was recorded. Per range, 20 frames were collected. Finally, the range accuracies were derived as a function of the number of averaged frames per range.

The identification of human targets including their activities and handheld objects at range is a prime military and security capability. We have investigated this capability using active and passive imaging for video cameras, and sensors operating in the NIR and SWIR regions. For a limited data set we also compare sensor imagery from visible, NIR and SWIR sensors with that from a thermal imaging camera. The target recognition performance is studied vs. the gate position relative to the target, target range, turbulence conditions and target movement. A resolution chart is also included in the scene. The performance results from observer tests are compared with models and discussed from a system perspective.

In the framework of this paper, AIM presents the actual status of some of its currently ongoing focal plane detector module developments for space applications covering the spectral range from the short-wavelength infrared (SWIR) to the long-wavelength infrared (LWIR) and very-long-wavelength infrared (VLWIR), where both imaging and spectroscopy applications will be addressed. In particular, the integrated detector cooler assemblies for a mid-wavelength infrared (MWIR) push-broom imaging satellite mission, for the German hyperspectral satellite mission EnMAP will be elaborated. Additionally dedicated detector modules for LWIR/VLWIR sounding, providing the possibility to have two different PVs driven by one ROIC will be addressed.

Current and past literature on the topic of detection statistics - in particular those used in hyperspectral target detection - can be intimidating for newcomers, especially given the huge number of detection tests described in the literature. Detection tests for hyperspectral measurements, such as those generated by dispersive or Fourier transform spectrometers used in remote sensing of atmospheric contaminants, are of paramount importance if any level of analysis automation is to be achieved. The detection statistics used in hyperspectral target detection are generally borrowed and adapted from other fields such as radar signal processing or acoustics. Consequently, although remarkable efforts have been made to clarify and categorize the vast number of available detection tests, understanding their differences, similarities, limits and other intricacies is still an exacting journey. Reasons for this state of affairs include heterogeneous nomenclature and mathematical notation, probably due to the multiple origins of hyperspectral target detection formalisms. Attempts at sorting out detection statistics using ambiguously defined properties may also cause more harm than good. Ultimately, a detection statistic is entirely characterized by its decision boundary. Thus, we propose to catalogue detection statistics according to the shape of their decision surfaces, which greatly simplifies this taxonomy exercise. We make a distinction between the topology resulting from the mathematical formulation of the statistic and mere parameters that adjust the boundary's precise shape, position and orientation. Using this simple approach, similarities between various common detection statistics are found, limit cases are reduced to simpler statistics, and a general understanding of the available detection tests and their properties becomes much easier to achieve.

The Kelantan estuary, located in the northeastern part of Peninsular Malaysia, is characterized by high levels of suspended sediments. Kuala Besar is the estuary of the river directly opposite South China Sea. Spectral reflectance (Rr) and transparency measurements were carried out in the Kelantan estuary. The objective in this study is to establish empirical relationships between spectral remote sensing reflectance in ALOS satellite imagery and water column transparency, i.e. nephelometric turbidity unit (NTU) and Secchi disc depth (SDD) through these numerous in situ measurements. We detected that remote sensing reflectance are linear and power regression functions against NTU and SDD. The results of this sampling show that the wavelengths range from 500-620 nm is the most suitable band for measuring water column transparency. The calibrated reflectance of ALOS AVNIR-2 bands was also regressed against NTU and SDD field data to derive two empirical equations for water transparency estimation. These equations were calculated using ALOS images data on June 12, 2010. The result obtained indicated that reliable estimates of turbidity and transparency values for the Kelantan Estuary, Malaysia, could be retrieved using this method.

Photon counting laser radar is the most sensitive and efficiency detection method of direct-detection laser radar. With the use of Geiger-mode avalanche photodiode (APD) or other single photon detectors, every laser photon could be sufficiently used for ranging and three-dimensional imaging. The average energy of received laser signal could be as low as a single photon, or even less than one. This feature of photon counting laser radar enables ranging under conditions of long range, low laser pulse energy, and multi-pixel detection, while receiver size, mass, power, and complexity of laser radar are reduced. In this paper, a latest multi-channel photon counting 3D imaging laser radar system using fiber array coupled Geiger-mode avalanche photodiode (APD) is introduced. Detection model based on Poisson statistics of a photon counting laser radar is discussed. A laser radar system, working under daylight condition with ultra-low signal level (less than single photon per pulse), has been designed and analyzed with the detection model and photon counting three-dimensional imaging theory. A passively Q-switched microchip laser is used to transmit short sub-nanosecond laser pulses at 532nm. The output laser is divided into 1×8 laser spots, which correspond to 8 Geiger-mode avalanche photodiodes coupled by a 1×8-pixel fiber array. A FPGA based time-to-digital converter (TDC), which is designed by delay line interpolation technology, is used for multi-hit signal acquisition. The algorithm of photon counting three-dimensional imaging is developed for signal photon events extraction and noise filter. Three-dimensional images under daylight conditions were acquired and analyzed. The results show that system could operate at strong solar background. The ranging accuracy of the system is 6.3cm (σ) while received laser pulse signal level is only 0.04 photoelectrons on average. The advantages and feasibility of photon counting laser radar working at daylight have been demonstrated experimentally.

Tomographic signal processing is used to transform multiple one-dimensional range profiles of a target from different angles to a two-dimensional image of the object. The range profiles are measured by a time-correlated single-photon counting (TCSPC) laser radar system with approximately 50 ps range resolution and a field of view that is wide compared to the measured objects. Measurements were performed in a lab environment with the targets mounted on a rotation stage. We show successful reconstruction of 2D-projections along the rotation axis of a boat model and removal of artefacts using a mask based on the convex hull. The independence of spatial resolution and the high sensitivity at a first glance makes this an interesting technology for very long range identification of passing objects such as high altitude UAVs and orbiting satellites but also the opposite problem of ship identification from high altitude platforms. To obtain an image with useful information measurements from a large angular sector around the object is needed, which is hard to obtain in practice. Examples of reconstructions using 90 and 150° sectors are given. In addition, the projection of the final image is along the rotation axis for the measurement and if this is not aligned with a major axis of the target the image information is limited. There are also practical problems to solve, for example that the distance from the sensor to the rotation centre needs to be known with an accuracy corresponding to the measurement resolution. The conclusion is that that laser radar tomography is useful only when the sensor is fixed and the target rotates around its own axis.

In order to avoid the shortcoming of the passive gain control method in the 3D imaging lidar (light detection and ranging), we propose a new gain control method, which can adjust the gain of the amplifying circuit according to the target distance. This method complies with the principle that the laser echo amplitude is inversely proportional to the square of the target distance. In addition, to simplify the complexity of the gain control module, we propose a simple implementation method based on the charging process of a capacitor. Firstly, the theoretical waveform of the proposed gain control method and the gain control error are analyzed and simulated. The results indicates that when the gain ranged from 1 to 100, the maximum of gain error is less than 28% in the whole target distance range, and the gain error is less than 5% in the most target distance range. Based on this method, a new gain control and amplifying circuit has been developed, which is mainly composed of an amplifying module and a gain control module. The gain control module is used to generate a gain control voltage and apply the voltage to the gain control of the amplifying module. Finally, some experiments have been carried out to verify the entire circuit functions and performances. The experimental results show that the output signal amplitude keep constant on the whole when the target distance is changing. The pass band of the circuit ranges from 0.33 MHz to 150 MHz, and the maximum gain is 316.

Combined 2D imaging and 3D ranging sensors provide useful information for both long (some kms) and short (few tens of m) distance, in security applications. To this aim, we designed two different monolithic imagers in a 0.35 μm costeffective CMOS technology, based on Single Photon Avalanche Diodes (SPADs), for long-range time-of-flight (TOF) and short-range phase-resolved depth ranging. The single pixel consists of a SPAD (30 μm diameter), a quenching circuit, and a Time-to-Digital Converter (TDC) for TOF measurements or three up/down synched counters for phaseresolved depth assessments. Such smart pixels operate in two different modalities: single photon-counting for 2D “intensity” images; while either photon-timing or phase-resolved photon-counting for 3D “depth” images. In 2D imaging, each pixel has a counter that accumulates the number of photons detected by the SPAD in the pixel, thus providing single-photon level sensitivity and high (100 kframe/s) frame-rate. In the TOF 3D imager, each pixel measures the photon arrival time with a 312 ps resolution, thanks to a two-stage TDC (with 6 bit coarse counter plus a 4 bit fine interpolator), with a 320 ns full-scale range. The resulting spatial resolution is 9 cm within a 50 m range, centered at any user-selectable distance (e.g. 100 m – 5 km), with linearity of DNLrms=4.9% LSB and INLrms=11.7% LSB, and 175 ps precision. In the phase-resolved 3D imager, the in-pixel electronics measures the phase difference between the modulated light emitted by a laser and the back-reflected light, with both continuous-wave and pulsed-light modulation techniques.

This paper shows the development of an optical instrument for vibrations measurements, without contact. The device is based on self-mixing interferometry, realized with very low optical complexity and cost. As any interferometer, it detects the power modulation of the beam laser, due to the remote target displacement. The signal is acquired by a Digital Signal Processor that provides to reconstruct the target movements, in real-time. Two different algorithms were developed to cover a great range of optical conditions. The best focus point is determined by an embedded autofocus system that moves the collimating lens driving a step-by-step engine. The measured distance ranges from 5 cm to 2 m, with a resolution of about 50 nm.

The detection and classification of small surface targets at long ranges is a growing need for naval security. Laser range profiling offers a new capability for detecting and classifying such targets even if they appear as point (transversally unresolved) targets in radar or passive/active imaging EO sensors. Modifying a conventional laser range finder to have a higher range resolution can this increase it’s value as a sensor. Laser range profiles will reveal basic reflecting structures on the ship. The best information is obtained for profiles along the ship. Several range profiles from different aspects will increase the classification performance. If many aspects angles are possible a tomographic reconstruction of the ship may be done. We have used high resolution (sub cm) laser radar based on time correlated single photon counting (TCSPC) to acquire range profiles from different small model ships. The collected waveforms are compared with simulated wave forms based on 3 D models of the ships. A discussion of the classification accuracy based on the number of waveforms from different aspect angles is done as well as the influence of the reflectivity from different parts of the ship is made. The results are discussed with respect to the potential performance of modified laser range finder measuring on real ships and the combination with active imaging.

The navigation of an autonomous robot vehicle and person localisation in the absence of GPS both rely on using local sensors to build a model of the 3D environment. Accomplishing such capabilities is not straightforward – there are many choices to be made of sensor and processing algorithms. Roke Manor Research has broad experience in this field, gained from building and characterising real-time systems that operate in the real world. This includes developing localization for planetary and indoor rovers, model building of indoor and outdoor environments, and most recently, the building of texture-mapped 3D surface models.

The paper presents new techniques for automatic segmentation, classification, and generic pose estimation of ships and boats in laser radar imagery. Segmentation, which primarily involves elimination of water reflections, is based on modeling surface waves and comparing the expected water reflection signature to the ladar intensity image. Shape classification matches a parametric shape representation of a generic ship hull with parameters extracted from the range image. The extracted parameter vector defines an instance of a geometric 3D model which can be registered with the range image for precision pose estimation. Results show that reliable automatic acquisition, aim point selection and realtime tracking of maritime targets is feasible even for erratic sensor and target motions, temporary occlusions, and evasive target maneuvers.

Autonomous target detection is an important goal in the wide-scale deployment of unattended sensor networks. Current approaches are often sample-centric with an emphasis on achieving maximal detection on any given isolated target signature received. This can often lead to both high false alarm rates and the frequent re-reporting of detected targets, given the required trade-off between detection sensitivity and false positive target detection. Here, by assuming that the number of samples on a true target will both be high and temporally consistent we can treat our given detection approach as a ensemble classifier distributed over time with classification from each sample, at each time-step, contributing to an overall detection threshold. Following this approach, we develop a mechanism whereby the temporal consistency of a given target must be statistically strong, over a given temporal window, for an onward detection to be reported.

If the sensor sample frequency and throughput is high, relative to target motion through the field of view (e.g. 25fps camera) then we can validly set such a temporal window to a value above the occurrence level of spurious false positive detections. This approach is illustrated using the example of automated real-time vehicle and people detection, in multi-modal visible (EO) and thermal (IR) imagery, deployed on an unattended dual-sensor pod. A sensitive target detection approach, based on a codebook mapping of visual features, classifies target regions initially extracted from the scene using an adaptive background model. The use of temporal filtering provides a consistent, fused onward information feed of targets detected from either or both sensors whilst minimizing the onward transmission of false positive detections and facilitating the use of an otherwise sensitive detection approaches within the robust target reporting context of a deployed sensor network.

A reliable indoor positioning system providing high accuracy has the potential to increase the safety of first responders and military personnel significantly. To enable navigation in a broad range of environments and obtain more accurate and robust positioning results, we propose a multi-sensor fusion approach. We describe and evaluate a positioning system, based on sensor fusion between a foot-mounted inertial measurement unit (IMU) and a camera-based system for simultaneous localization and mapping (SLAM). The complete system provides accurate navigation in many relevant environments without depending on preinstalled infrastructure. The camera-based system uses both inertial measurements and visual data, thereby enabling navigation also in environments and scenarios where one of the sensors provides unreliable data during a few seconds. When sufficient light is available, the camera-based system generally provides good performance. The foot-mounted system provides accurate positioning when distinct steps can be detected, e.g., during walking and running, even in dark or smoke-filled environments. By combining the two systems, the integrated positioning system can be expected to enable accurate navigation in almost all kinds of environments and scenarios. In this paper we present results from initial tests, which show that the proposed sensor fusion improves the navigation solution considerably in scenarios where either the foot-mounted or camera-based system is unable to navigate on its own.

In this paper we propose an object tracking approach that includes the selection of the appropriate coordinate estimation method from the set of base methods: cross-correlation, statistical segmentation, methods based on spatial and spatiotemporal filtering. The tracking performance of the base methods is estimated by means of the several parameters (performance features) that describe the reliability of tracking. The features are invariant to the changes of the mean brightness, contrast, scale and rotation. The comparison of the performance of the methods is based on the binary performance characteristic that describes the tracking in the terms of work/not work. The proposed object tracking algorithm is implemented in five steps which are carried out on each frame: the calculation of the performance feature for each base coordinate estimation method, the calculation of the binary performance characteristic for each method, the selection of the appropriate method, the estimation of the object coordinates using the selected method, the correction of the tracking process performed by other methods. The algorithm shows a good tracking performance during the variations of the observation conditions. In most cases it comprises the main advantages of each of the source methods.

In general, long range visual detection, recognition and identification are hampered by turbulence caused by atmospheric conditions. Much research has been devoted to the field of turbulence compensation. One of the main advantages of turbulence compensation is that it enables visual identification over larger distances. In many (military) scenarios this is of crucial importance. In this paper we give an overview of several software and hardware approaches to compensate for the visual artifacts caused by turbulence. These approaches are very diverse and range from the use of dedicated hardware, such as adaptive optics, to the use of software methods, such as deconvolution and lucky imaging. For each approach the pros and cons are given and it is indicated for which type of scenario this approach is useful. In more detail we describe the turbulence compensation methods TNO has developed in the last years and place them in the context of the different turbulence compensation approaches and TNO’s turbulence compensation roadmap. Furthermore we look forward and indicate the upcoming challenges in the field of turbulence compensation.

Range Imaging (RI) has sparked an enthusiastic interest recently due to the numerous applications that can benefit from the presence 3D data. One of the most successful techniques for RI employs Time-of-Flight (ToF) cameras which emit and subsequently record laser pulses in order to estimate the distance between the camera and an object. A limitation of this class of RI is the requirement for a large number of frames that have to be captured in order to generate high resolution depth maps. In this work, we propose a novel approach for ToF based RI that utilizes the recently proposed framework of Compressed Sensing to dramatically reduce the number of necessary frames. Our technique employs a random gating function along with state-of-the-art minimization techniques in order to estimate the location of a returning laser pulse and infer the distance. To validate the theoretical motivation, software simulations were carried out. Our simulated results have shown that reconstruction of a depth map is possible from as low as 10% of the frames that traditional ToF cameras require with minimum reconstruction error while 20% sampling rates can achieve almost perfect reconstruction in low resolution regimes. Our experimental results have also shown that the proposed method is robust to various types of noise and applicable to realistic signal models.

Counting people in crowds is a common problem in visual surveillance. Many solutions are just designed to count less than one hundred people. Only few systems have been tested on large crowds of several hundred people and no known counting system has been tested on crowds of several thousand people. Furthermore, none of these large scale systems delivers people's positions, they just estimate the number. But having the position of people would be a large benefit, since this would enable a human observer to carry out a plausibility check. In addition, most approaches require video data as input or a scene model. In order to generally solve the problem, these assumptions must not be made. We propose a system that can count people on single aerial images including mosaic images generated from video data. No assumptions about crowd density will be made, i. e. the system has to work from low to very high density. The main challenge is the large variety of possible input data. Typical scenarios would be public events such as demonstrations or open air concerts. Our system uses a model-based detection of individual humans. This includes the determination of their positions and the total number. In order to cope with the given challenges we divide our system into three steps: foreground segmentation, person size determination and person detection. We evaluate our proposed system on a variety of aerial images showing large crowds with up to several thousand people

For high resolution satellite remote sensing cameras, the line of sight (LOS) moving during the image exposure period will cause the modulation transfer function (MTF) degradation and image blurring. Image stabilization component is used to improve image quality by actively removing the apparent motion induced by vibration, tracking error and attitude instability. In this paper, the image stabilization component is considered as a kind of closed loop servo control system, and the image stabilization effect is converted into servo control performance for research. Firstly, the image stabilization servo loop scheme and transfer function model are constructed and the LOS jitter is considered as the output of a stochastic system derived by white-Gaussian noise. Based on the proposed model, the demand boundary of jitter rejection function is described, and the design criterion to be satisfied is obtained according to the requirement of image stabilization performance. And then, a discrete Kalman estimation algorithm is introduced into image stabilization servo loop to filter out the noise caused by pixel-shift sensor (PSS) and compensate for the delay due to the PSS measurement. Based on the given design criterion, the control law is designed by using the output of Kalman filter. The computer simulation is achieved to show that the proposed control strategy can significantly improve the image stabilization performance.

In order to enhance the measurement precision and detection range of the 3D imaging lidar (light detection and ranging), we propose a new broadband low-noise detection circuit for the pulse laser, which mainly includes a high-speed APD (Avalanche Photodiode) detector and a broadband low-noise transimpedance amplifier. In the detection circuit, a high negative bias voltage is applied to the APD detector and used to set the static input current of the amplifier NE5210 to 200 μA with a proper bias method. By this bias method, the allowable input current range of the amplifier NE5210 is enhanced by about 1 time. This paper introduces the main framework and performance of the detection circuit. The output noise voltage, output signal voltage and voltage SNR (Signal-to-noise Ratio) of the detection circuit are analyzed and calculated as well. Some experiments have been carried out with the proposed detection circuit, showing that the detection circuit can detect a narrow pulse laser with about 4 ns pulse width. Based on our experiments and analyses, the pass band of the detection circuit ranges from 0.56 MHz to 200MHz approximately, the allowable input current of the amplifier NE5210 varies from -460 μA to 0, and the effective output differential voltage ranges from -1.6 V to 1.4 V. The proposed detection circuit is implemented and tested in a high-speed 3D imaging lidar. As well as 3D imaging lidars, the detection circuit can be applied to the pulse laser range finder and other pulse laser detection system.

Inertially stabilized platform (ISP) is indispensable for various imaging systems to segregate the base angular movement and achieve high LOS (Line-Of-Sight) stability. The disturbance rejection ratio and command following performance are of primary concern in designing ISP control systems. In this paper, the redundant gimbals ISP system is considered and it is shown to experience complex disturbance and parameter variation during operation. To meet advanced LOS stabilization requirement, a disturbance observer based (DOB) dual-loop controller design for ISP is proposed of which the DOB is the internal-loop. Using a nominal plant model and a low-pass filter, the disturbance signal is estimated and used as a cancellation input added to the current command of torque motor. If the DOB works well, the disturbance torque and mismatch between nominal plant and actual plant will be compensated and the internal-loop will behave as nominal model parameters. On the other hand, the external-loop will be designed for nominal model parameters to meet stabilization requirements. This paper will mainly focus on the DOB design method. Since the low-pass filter of DOB determines the sensitivity and complementary sensitivity function as will be shown in this paper, designing the filter is the most important consideration. In this paper, an optimal low-pass filter design method is proposed. The method is intuitive, simple to implement and allows on-line tuning. Simulation results show the performance enhancement of our control structure in the presence of disturbance and measurement noise.

As presented in September 2010 in Toulouse CI Systems has been developing the technology to produce Circular Variable Filters (CVF) production. These filters are used as monochromators of medium spectral resolution in radiometric and spectroradiometric instrumentation for spectroscopic and remote sensing applications in the laboratory and in the field. As mentioned then, OCLI, the original US company that developed the old CVF technology, stopped production in the ‘90’s and CI started to reconstruct the technology in 2009. The first results of CVF performance following this new work were presented in the wavelength region of 1.3 to 2.5 microns in 2010. Since then we made significant progress and completed the development of segments from the visible range up to 14.3 microns, with a spectral resolution in the range of 0.5% to 2% of the peak wavelength. The advantage of the new production method is that both the so called “tooling factor” and the peak wavelength profile along the circumference are controlled by software instead of by fixed hardware gear ratios, yielding higher design flexibility. A new CVF model in the 7.7 to 12.6 micron range with the highest spectral resolution (0.5% FWHM) ever being produced has also been developed.

This paper presents the development of an optical rangefinder based on self-mixing interferometry. The instrument measures the absolute distance from a remote target, without contact and respecting the Class I safety. A variation of the laser diode bias current origins a modulation of the wavelength and then, due to the phase shift along the channel path, the presence of a target generates interferometric fringes. The electrical frequency of the fringes signal is proportional to the target distance. The realized device consists in analog and digital circuits. The analog circuits drive the laser diode, detect the interferometric signal and filter it. A Digital Signal Processor is needed to acquire the fringes signal and, by extracting its frequency, evaluate the absolute distance. The developed rangefinder allows spatial resolution better than 100 μm over a range from 5 cm to 2 m.

This paper presents the utilities of remote sensing technique for water quality assessment in Kelantan Delta, Malaysia. Remote sensing is one of the effective methods for water quality monitoring through image analysis of study area. Spectral reflectance signatures of Kelantan Delta were measured from 20 stations using ASD Handheld spectroradiometer from regions with different turbidity level. Water samples collected from these stations were taken to the laboratory for measure turbidity in Nephelometric Turbidity Unit (NTU). The objective of this study is to examine the potential of ALOS on Japanese Earth Observing Satellite (JEOS) for assessing water quality in Kelantan Delta. There is a large correlation between NTU and the in-situ reflectance at 500 - 620 nm (maximum spectra band between 300 and 1100 nm) is shown by multiple linier regression model, resulting from increasing of turbidity levels, was developed and applied to ALOS band 2 and band 3 (0.42-069 nm). A simple atmospheric correction, based on darkest pixel technique was performed in this study. The ALOS data provides accurate estimates of the mean water quality (R2 = 0.95 and RMSE = 2.26 NTU). The result acquired is reliable to estimate of water quality values for the Kelantan Delta and its implication for future operation.

Accurate and fast curve detection in images is a challenging computer vision problem. HT(Hough transform) is one of the most widely used techniques for curve detection. Existing HT-based methods have disadvantages of low accuracy and low speed. In this paper, a new and efficient Hough Transform for curve detection is presented. In view of kinematics, a curve can be regarded as movement trajectory of a given point, and point's velocity direction is the tangential direction of point on the smooth curve. Thus the main contributions are threefold. 1) We formulate the problem of curve detection as robustly fit curve in the connected region. 2) We propose the direction elements and directional control scheme to quickly discover the smooth curve. 3) We use a coarse-to-fine strategy to efficiently detect the final curve. We have tested our algorithm on simulated and natural image. Compared to other classical curve detection methods, experimental results indicated that our algorithm reduces the time cost and improves the detection accuracy greatly.

Coded apertures were originally developed by the high-energy astrophysical community for use in imaging high-energy photons (x- and γ-rays) for which focusing optics are ineffective. We are now taking what was developed as a tool for use in the extreme far field at high energies to encode spatial information at optical wavelengths in the extreme near field to enhance the performance of position-sensitive x- and gamma-ray scintillator detectors. Spatial resolution for events within bulk scintillators is limited by the size of the light “spot” available at the sides of the scintillator, where phototransducers convert the light to an electrical signal. The ability to localize an event is determined by how well one can determine the centroid and the size of the spot. Generally, performance is limited to many millimeters in all three spatial dimensions, and one cannot resolve simultaneous events that are closer together than the width of the light spot (frequently of order 10 mm). For this reason, many applications requiring the finest spatial resolution subdivide the scintillator into tiny elements and use a digital approach to determine event location. However, that technique significantly complicates the overall instrument and sacrifices energy resolution because the light collection efficiency varies with event location within the subdivided scintillator. We are building a device that overcomes these shortcomings by using an optical coded-aperture shadow mask between a bulk crystal and a position-sensitive phototransducer. Simulations indicate that we can achieve millimeter-scale localization in all three spatial dimensions while resolving simultaneous energy depositions. The technique and progress toward its realization will be presented.

Synthetic Aperture Radar (SAR) is a mature technology that overcomes the diffraction limit of an imaging system’s real aperture by taking advantage of the platform motion to coherently sample multiple sections of an aperture much larger than the physical one. Synthetic Aperture Lidar (SAL) is the extension of SAR to much shorter wavelengths (1.5 μm vs 5 cm). This new technology can offer higher resolution images in day or night time as well as in certain adverse conditions. It could be a powerful tool for Earth monitoring (ship detection, frontier surveillance, ocean monitoring) from aircraft, unattended aerial vehicle (UAV) or spatial platforms. A continuous flow of high-resolution images covering large areas would however produce a large amount of data involving a high cost in term of post-processing computational time. This paper presents a laboratory demonstration of a SAL system complete with image reconstruction based on optronic processing. This differs from the more traditional digital approach by its real-time processing capability. The SAL system is discussed and images obtained from a non-metallic diffuse target at ranges up to 3m are shown, these images being processed by a real-time optronic SAR processor origiinally designed to reconstruct SAR images from ENVISAT/ASAR data.

We report on the performance of a photon-counting optical communication system which was used to transmit optical data at clock rates (not detection rates) of 40Mb/s at a wavelength of 450nm. The transmitted test data patterns comprised of one page of ASCII text preceded by a pseudo-random sequence used as a timing reference pattern by the receiver. The optical data patterns were transmitted through an aquarium tank containing ~110 litres of water and were detected at the receiver by a shallow junction silicon single photon avalanche diode detector. An antacid, brand name Maalox, was introduced into the tank to increase the scattering of the optical pulses. The bit error rate and bit rate of the transmitted data were investigated for a range of Maalox concentrations. The optical attenuation and pulse distortion caused by the introduction of Maalox was also investigated.

The performance of single image deblurring algorithms is typically evaluated via a certain discrepancy measure between the reconstructed image and the ideal sharp image. The choice of metric, however, has been a source of debate and has also led to alternative metrics based on human visual perception. While fixed metrics may fail to capture some small but visible artifacts, perception-based metrics may favor reconstructions with artifacts that are visually pleasant. To overcome these limitations, we propose to assess the quality of reconstructed images via a task-driven metric. In this paper we consider object classification as the task and therefore use the rate of classification as the metric to measure deblurring performance. In our evaluation we use data with different types of blur in two cases: Optical Character Recognition (OCR), where the goal is to recognise characters in a black and white image, and object classification with no restrictions on pose, illumination and orientation. Finally, we show how off-the-shelf classification algorithms benefit from working with deblurred images.

In the nanoscale structure of a wide variety of material systems, a close juxtaposition of optically responsive components can lead to the absorption of light by one species producing fluorescence that is clearly attributable to another. The effect is generally evident in systems comprising two or more light-absorbing components (molecules, chromophores or quantum dots) with well-characterised fluorescence bands at similar, differentiable wavelengths. This enables the fluorescence associated with transferred energy to be discriminated against fluorescence from an initially excited component. The fundamental mechanism at the heart of the phenomenon, molecular (resonance) energy transfer, also operates in systems where the product of optical absorption is optical frequency up-conversion. In contrast to random media, structurally organised materials offer the possibility of pre-configured control over the delocalization of energy, through molecular energy transfer following optical excitation. The Förster mechanism that conveys energy between molecular-scale components is strongly sensitive to specific forms of correlation between the involved components, in terms of position, spectroscopic character, and orientation; one key factor is a spectroscopic gradient. Suitably designed materials offer a broad scope for the widespread exploitation of such features, in applications ranging from chemical and biological sensing to the detection of nanoscale motion or molecular conformations. Recently, attention has turned to the prospect of actively controlling the process of energy migration, for example by changing the relative efficiencies of fluorescence and molecular energy transfer. On application of static electric fields or off-resonant laser light – just two of the possibilities – each represents a means for achieving active control with ultrafast response, in suitably configured systems. As the principles are established and the theory is developed, a range of new possibilities for technical application is emerging. For example, applications can be envisaged for new forms of all-optical switching and transistor action. There is also interest in engaging with the interplay of optical excitation and local nanoscale force, exploiting local responses to changes in dispersion forces, accompanying molecular energy transfer.

Recent results from our work using ultrafast laser writing to fabricate waveguides and on-chip devices inside sulphide chalcogenide glasses are presented in this paper. Low loss single-mode (SM) and multi-mode (MM) waveguide arrays were successfully laser fabricated, for the first time to our knowledge, for operation in the whole near-IR (NIR) to mid- IR (MIR) range (1 to 11 μm wavelengths). These waveguides are demonstrated to have numerical apertures (NA) which can exceed NA=0.2, therefore also allowing for low bend losses as well as direct coupling to QC lasers. We also demonstrate the control over the waveguide mode field diameters (MFDs) (at 1/e²) by changing the waveguide core sizes and index contrasts, achieving typical values of 44 μm at 10.6 μm, down to 6 μm for telecom 1.55 μm light. The optical nonlinear properties of these waveguides have also been preliminarily investigated. Using a femtosecond (fs) optical parametric amplifier system, the optical nonlinearity of bulk gallium lanthanum sulphide (GLS) glass was first measured at 2.5 μm. The upper limits for the nonlinear properties of the laser modified material could be estimated based upon the nonlinear spectral broadening of a 2.5 μm fs pulse train coupled into SM waveguides. Further work includes the demonstration of on-chip three dimensional (3D) beam combiners for the MIR range (10.6 μm in this work), for near future implementation in astronomical observatories for stellar interferometry.

SELEX Galileo Infrared Ltd has developed a range of 3^rd Generation infrared detectors based on HgCdTe grown by Metal Organic Vapour Phase Epitaxy (MOVPE) on low cost GaAs substrates. There have been four key development aims: reducing the cost especially for large arrays, extending the wavelength range, improving the operating temperature for lower power, size and weight cameras and increasing the functionality. Despite a 14% lattice mismatch between GaAs and HgCdTe MOVPE arrays show few symptoms of misfit dislocations even in longwave detectors. The key factors in the growth and device technology are described in this paper to explain at a scientific level the radiometric quality of MOVPE arrays. A feature of the past few years has been the increasingly sophisticated products that are emerging thanks to custom designed silicon readout devices. Three devices are described as examples: a multifunctional device that can operate as an active or passive imager with built-in range finder, a 3-side buttable megapixel array and an ultra-low noise device designed for scientific applications.

Metamaterial research is an extremely important global activity that promises to change our lives in many different ways. These include making objects invisible and the dramatic impact of metamaterials upon the energy and medical sectors of society. Behind all of the applications, however, lies the business of creating metamaterials that are not going to be crippled by the kind of loss that is naturally heralded by use of resonant responses in their construction. Under the general heading of active and tunable metamaterials, an elegant route to the inclusion of nonlinearity and waveguide complexity coupled to soliton behavior suggested by forms of transformation dynamics is presented. In addition, various discussions will be framed within a magnetooptical environment that deploys externally applied magnetic field orientations. Light can then be directed to achieve energy control and be deployed for a variety of outcomes. Quite apart from the fact that the manufacture of metamaterials is attracting such a lot of global attention, the ability to control light, for example, in these materials is also immensely interesting and will lead to a new dawn of integrated circuits and computers. Recognizing the role of nonlinearity raises the possibility that dramatic manufacturing and applications are on the horizon.

The latest developments in AlGaInN laser diode technology is reviewed for defence applications such as underwater telecommunications, sensor systems etc. The AlGaInN material system allows for laser diodes to be fabricated over a very wide range of wavelengths from u.v., i.e, 380nm, to the visible, i.e., 530nm, by tuning the indium content of the laser GaInN quantum well. Advantages of using Plasma assisted MBE (PAMBE) compared to more conventional MOCVD epitaxy to grow AlGaInN laser structures are highlighted. Ridge waveguide laser diode structures are fabricated to achieve single mode operation with optical powers of <100mW in the 400-420nm wavelength range with high reliability. High power operation of AlGaInN laser diodes is also reviewed. We demonstrate the operation of a single chip, high power AlGaInN laser diode 'mini-array' consisting of a 3 stripe common p-contact configuration at powers up to 2.5W cw in the 408-412 nm wavelength range. Low defectivity and highly uniform TopGaN GaN substrates allow arrays and bars of nitride lasers to be fabricated. Packaging of nitride laser diodes is substantially different compared to GaAs laser technology and new processes and techniques are required to optimize the optical power from a nitride laser bar. Laser bars of up to 5mm with 20 emitters have shown optical powers up to 4W cw at ~410nm with a common contact configuration. An alternative package configuration for AlGaInN laser arrays allows for each individual laser to be individually addressable allowing complex free-space and/or fibre optic system integration within a very small form-factor. TopGaN are developing a new range of high power laser array technology over the u.v.- visible spectrum together with new packaging solutions for optical integration.

Recent years have seen the development of a range of promising optical fibre technologies emerge, enabled by advances in materials and fabrication techniques. We describe 3 emerging areas in optical fibre developments: nanomechanical optical fibres, microstructured hollow core silica fibres for high peak optical power and/or extended infrared transmission, and chalcogenide glasses and fibres for mid-IR applications.

Compressed sensing as an imaging method has become very popular among scientists and is becoming more and more popular among hardware manufacturers. There are many hardware variants of single-pixel compressed sensing based camera and there are many algorithms of sparse signal approximations. This fact makes it appear more and more applications of compressive imaging. Recently, many algorithms for signal reconstruction have been developed, however, all of them need many parameters to be properly set before using. Setting proper parameters is crucial for preparing a real model of the single pixel camera as well as for fast and efficient image synthesis. Because of high complexity of image recovery algorithms, image synthesis process needs to be optimized. Optimization of signal acquisition and processing parameters can be achieved running various camera simulations. In the paper we present the integrated test environment for image synthesis of the single pixel camera and the test results of simulations run with various configurations and parameters values. We used two combined adaptive methods for image reconstruction - the Newton method and the conjugate gradient method. Test environment allows to run two kinds of tests. The first test type is simulation of various parameters of acquired signal e.g. bit resolution. Image geometric transformation like rotation is the second type of tests. Simulation results include quality parameters values of MSE, PSNR and SSIM and image reconstruction time. Integrated test environment can be used during the process of hardware selection as well as during camera tests with real signals.

An attempt is made to study the energy spectrum of the transmission electrons and analogous density-of-states function of degenerate semiconductors in the occurrence of an electric field strength. It is found, captivating n-GaAs as an example that the isotropic parabolic energy spectrum converts into an anisotropic dispersion relation with energy dependent mass anisotropy in the occurrence of electric field strength. In addition the band gap increases with electric field strength and the carriers vanish from the transmission band edge after definite value of the electric field strength. The eminent consequence of the density-of-states function for non-degenerate wide gap optical and optoelectronic materials with parabolic energy band has been obtained as special cases of our generalized theory under definite limiting background from our generalized term when electric field strength is zero.

Quantum cryptography was designed to provide a new approach to the problem of distributing keys for private-key cryptography. The principal idea is that security can be ensured by exploiting the laws of quantum physics and, in particular, by the fact that any attempt to measure a quantum state will change it uncontrollably. This change can be detected by the legitimate users of the communication channel and so reveal to them the presence of an eavesdropper. In this paper I explain (briefly) how quantum key distribution works and some of the progress that has been made towards making this a viable technology. With the principles of quantum communication and quantum key distribution firmly established, it is perhaps time to consider how efficient it can be made. It is interesting to ask, in particular, how many bits of information might reasonably be encoded securely on each photon. The use of photons entangled in their time of arrival might make it possible to achieve data rates in excess of 10 bits per photon.

A quantum bug, or "qbug", is the fundamental unit of problems in quantum key distribution. It can include a particular attack, an inaccurate use of the technology, a loophole of the theory or a hidden side channel. In this manuscript we detail one of them, related to the choice of the protocol and its security proof in the finite-size scenario. The treatment makes use of linear programming, a tool that well adapts to the practical constraints imposed by an actual quantum key distribution set up.

Quantum key distribution (QKD) protocols allow two trusted parties to distribute a cryptographic key which they can further use for the unconditionally secure classical communication. During the last decades the field has grown mature with the commercial prototypes being available. They mostly rely on the faint laser pulses implementing the protocols on the basis of single qubits and qubit pairs. Alternatively, the continuous-variable (CV) protocols based on the multi-photon states of light were developed recently. They are typically built using the quadrature modulation of the coherent or squeezed states and subsequent homodyne detection. In the case of Gaussian modulation the security of the protocols is based on the extremality of Gaussian states, which allows estimating bounds on the leaked information. The Gaussian CV QKD protocols were shown secure for any degree of channel attenuation, but are restricted by the channel noise. Moreover, the applicability of Gaussian CV QKD protocols is limited by the effectiveness of classical post-processing algorithms, used by the trusted parties to process the measured data and distill the cryptographic key. On the other hand, the squeezedstate CV QKD protocols were previously considered ineffective under limited degrees of squeezing, while strong squeezing remains experimentally challenging. In the present work we distinguish between the classical and quantum resources in the Gaussian CV QKD and address the role of nonclassicality in the Gaussian protocols. We demonstrate, that by properly combining squeezed resource and coherent modulation, trusted parties are able to decouple eavesdropper from the channel, thus being able to establish the secure key from any amount of the classical mutual information. Our result shows a very promising path towards the long-distance CV QKD.

Quantum Key Distribution together with its intrinsic security represent the more promising technology to meet the challenging requests of novel generation communication protocols. Beyond its relevant commercial interests, QKD is currently and deeply investigated in research fields as quantum information and quantum mechanics foundations, in order to push over the limits of the actual resources needed to ensure the security of quantum communication. Aim of the paper is to contribute to this open debate presenting our last experimental implementations concerning two novel quantum cryptographic schemes which do not require some of the most widely accepted conditions for realizing QKD. The first is Goldenberg-Vaidman^1,2 protocol, in which even if only orthogonal states (that in principle can be cloned without altering the quantum state) are used, any eavesdropping attempt is detectable. The second is N09³ protocol which, being based on the quantum counterfactual effect, does not even require any actual photon transmission in the quantum channel between the parties for the communication. The good agreement between theoretical predictions and experimental results represent a proof of principle of the experimental feasibility of the novel protocols.

Digital signature schemes are often used in interconnected computer networks to verify the origin and authenticity of messages. Current classical digital signature schemes based on so-called “one-way functions” rely on computational complexity to provide security over sufficiently long timescales. However, there are currently no mathematical proofs that such functions will always be computationally complex. Quantum digital signatures offers a means of confirming both origin and authenticity of a message with security verified by information theoretical limits. The message cannot be forged or repudiated. We have constructed, tested and analyzed the security of what is, to the best of our knowledge, the first example of an experimental quantum digital signature system.

The information carried by a photon can be encoded in one or more of many different degrees of freedom. Beyond the two-dimensional space of polarisation (spin angular momentum) our interest lies in the unbounded yet discrete state space of Orbital Angular Momentum (OAM). We examine how photon pairs can be generated and measured over a large range of OAM states.

Transmission volume holograms are evaluated as quantum projectors operating on spatial modes of the photon in mutually unbiased bases (MUBs). With applications to free-space quantum key distribution (QKD) in mind, state spaces based on rectilinear and azimuthal phase modes (i.e. photon linear and orbital angular momenta) are considered. Rectilinear phase modulation is shown to result in both greater mode densities for a receiving aperture in the far field and better efficiency and cross-talk characteristics when volume holograms are used as de-multiplexing elements. Twoand four-dimensional state spaces are defined via rectilinear phase modes and the complex optical fields of the MUBs are calculated and generated with a spatial light modulator in order to record and subsequently illuminate transmission volume holograms. Using holograms prepared in lithium niobate, diffraction efficiencies are measured for the 36 permutations associated with projecting the six MUB states of a two-dimensional state space onto the same six MUB states. Quantum measurements associated with cascaded projection operations in a four-dimensional state space are performed using photo-thermo-refractive glass holograms. Experimental results show approximate agreement with the inner-product relationships that describe quantum projection probabilities.

The desire to increase the amount of information that can be encoded onto a single photon has driven research into many areas of optics. One such area is optical orbital angular momentum (OAM) [1]. These beams have helical phasefronts and carry an orbital angular momentum of mbar per photon, where the integer m is unbounded, giving a large state space in which to encode information. We recently developed a telescope system comprising two bespoke refractive optical elements to transform OAM states into transverse momentum states [2]. This is achieved by mapping the azimuthal position of the input plane to the lateral position in the output [3]. A mapping of this type transforms a set of concentric rings at the input plane into a set of parallel lines in the output plane. A lens can then separate the resulting transverse momentum states into specified lateral positions, allowing for the efficient measurement of multiple OAM states simultaneously. Separating OAM states in this way presents an opportunity for this larger alphabet to improve the data capacity of a free space link and has potential application in both the classical and quantum regimes. We will present our latest design, increasing the bandwidth of measurable states to over 50 OAM modes. In such a system we study the crosstalk introduced by a thin phase turbulence, showing that turbulence similarly degrades the purity of all the modes within this range.

The bandwidth of any communication system, classical or quantum, is limited by the number of orthogonal states in which the information can be encoded. Quantum key distribution systems available commercially rely on the two-dimensional polarisation state of photons. Quantum computation has also been largely designed on the basis of qubits. However, a photon is endowed with other degrees of freedom, such as orbital angular momentum (OAM). OAM is an attractive basis to be used for quantum information because it is discrete and theoretically infinite-dimensional. This promises a higher information capacity per photon which can lead to more complex quantum computation protocols and more security and robustness for quantum cryptography. Entanglement of OAM naturally arises from spontaneous parametric down-conversion (SPDC). However, any practical experiment utilising the innately high-dimensional entanglement of the orbital angular momentum (OAM) state space of photons is subject to the modal capacity of the detection system. Only a finite subset of this space is accessible experimentally. Given such a constraint, we show that the number of measured, entangled OAM modes in photon pairs generated by SPDC can be increased by tuning the phase-matching conditions in the SPDC process. We achieve this by tuning the orientation angle of the nonlinear crystal generating the entangled photons.

Using an electron multiplying CCD camera we observe both image plane (position) and far field (momentum) correlations between photon pairs produced from spontaneous parametric down-conversion when using a 201 x 201 bi-dimensional array of pixels and a flux of around 0.02 photons/pixel. After background subtraction we characterize the strength of signal and idler correlations in both transverse dimensions by applying entanglement and EPR criteria, showing good agreement with the theoretical predictions. The application of such devices in quantum optics could have a wide range, including quantum computation with spatial degrees of freedom of single photons.

The implementation and commercialization of quantum cryptography technologies have to face some challenges related to the development of single-photon detectors operating at 1550 nm. The main requirements are: i) high detection efficiency; ii) low noise; iii) high count rate; iv) low timing jitter. Different technologies are currently available for single-photon detection at 1550 nm, but semiconductor devices (like Single-Photon Avalanche Diode, SPAD) offer a photon detection efficiency that is inherently higher than any photocathode employed in vacuum tube detectors. Additionally InGaAs/InP SPADs can detect single photons at 1550 nm with low noise when moderately cooled by means of thermo-electric coolers. Consequently, InGaAs/InP SPAD can be the enabling technology of practical quantum key distribution (QKD) systems, provided that the maximum count rate is increased above 1 Mcps. The main limit is the afterpulsing effect that usually sets too long (< 10 μs) a hold-off time after each avalanche ignition. We present the developments achieved in InGaAs/InP SPAD device design, fabrication technology and front-end electronics, aimed at decreasing the afterpulsing effect, while not impairing photon detection efficiency and timing jitter. The new InGaAs/InP SPADs provide count rates higher than 1 Mcps and temporal response with 60 ps Full-Width at Half Maximum and very short (30 ps time constant) tail. The front-end electronics includes a wide-band pulse generator able to gate the SPAD up to 133 MHz repetition rate. Eventually, a fast avalanche-quenching scheme minimizes quenching time to less than 1 ns, thus effectively reducing afterpulsing by decreasing the total charge flowing through the junction.

We present a general purpose theoretical model of single-photon detectors in quantum key distribution systems and apply it to an autonomous gigahertz clocked phase basis set system operating at a wavelength of 850 nm over a standard telecommunications fiber quantum channel. The system has been demonstrated using a variety of different singlephoton detectors, including thick and thin junction silicon single-photon avalanche photodiodes and the first implementation of a resonant cavity thin junction silicon single-photon avalanche diode. We show, by means of the theoretical model, how improvements to certain detector parameters can optimize key exchange rates.

A novel technique for anomalous change detection in hyperspectral images is presented. It adaptively measures the spectral distance between corresponding pixels in multi-temporal images by exploiting the local estimates of the signal to noise ratio for each spectral component of the pixel under test. Different metrics have been compared, based on multidimensional angular distance. Results obtained by applying the new algorithm to real data are presented and discussed. Performance evaluation highlighted the effectiveness of the proposed approach with respect to traditional methods, resulting in a consistent improvement of both the probability of detection of changes and the capability of suppressing the background.

Hyperspectral imaging is used in various applications to identify and classify the materials present in a scene. Often the requirement is to detect a specific target material, a single style of red shirt for example, and spectral processing selects only that singular object. This paper explains a novel new approach to identifying much larger and more spectrally varied classes of objects, using the specific example of ‘people’, based on a series of spectral matched filter style algorithms. This new approach has successfully been demonstrated against a range of targets in various scenarios alongside current thermal imaging techniques for person identification.

In this paper, a prior knowledge model is proposed in order to increase the effectiveness of a multidimensional striping noise compensation (SNC) algorithm. This is accomplished by considering an optoelectronic approach, thereby generating a more accurate mathematical representation of the hyperspectral acquisition process. The proposed model includes knowledge on the system spectral response, which can be obtained by means of an input with known spectral radiation. Further, the model also considers the dependence of the noise structure on the analog-digital conversion process, that is, schemes such as active-pixel sensor (APS) and passive-pixel sensor (PPS) have been considered. Finally, the model takes advantage of the degree of crosstalk between consecutive bands in order to determinate how much of this spectral information is contributing to the read out data obtained in a particular band. All prior knowledge is obtained by a series of experimental analysis, and then integrated into the model. After estimating the required parameters, the applicability of the multidimensional SNC is illustrated by compensating for stripping noise in hyperspectral images acquired using an experimental setup. A laboratory prototype, based on both a Photonfocus Hurricane hyperspectral camera and a Xeva Xenics NIR hyperspectral camera, has been implemented to acquire data in the range of 400-1000 [nm] and 900-1700 [nm], respectively. Also, a mobile platform has been used to simulate and synchronize the scanning procedure of the cameras and an uniform tungsten lamp has been installed to ensure an equal spectral radiance between the different bands for calibration purpose.

AISA hyperspectral imagers have been utilized in airborne applications for various defense related Intelligence, Surveillance and Reconnaissance (ISR) applications. In expanding the utility and capabilities of hyperspectral imagers for defense related applications, the implementation in a ground scanning configuration for check-point and forensic purposes has been achieved. System specifications, design, and operational considerations for a fully automated, near real-time target detection capability are presented. The system utilizes modularized software architecture, combining C++ command, capture, calibration, and messaging functions with drop-in IDL exploitation module for detection algorithm and target set flexibility. Performance capability against known defense related targets of interest have been tested, verified, and are presented utilizing full 400-2450nm spectral range provided by combined AisaEAGLE and AisaHAWK hyperspectral imagers. Initial results are also described for a new extended InGaAs system, covering 585-1630nm to provide a similar capability for integrations which have size, weight, and power restrictions.

The design and implementation of a compact multiple-image Fourier transform spectrometer (FTS) is presented. Based on the multiple-image FTS originally developed by A. Hirai, the presented device offers significant advantages over his original implementation. Namely, its birefringent nature results in a common-path interferometer which makes the spectrometer insensitive to vibration. Furthermore, it enables the potential of making the instrument ultra-compact, thereby improving the portability of the sensor. The theory of the birefringent FTS is provided, followed by details of its specific embodiment. A laboratory proof of concept of the sensor, designed and developed at the Optical Detection Lab, is also presented. Spectral measurements of laboratory sources are provided, including measurements of light-emitting diodes and gas-discharge lamps. These spectra are verified against a calibrated Ocean Optics USB2000 spectrometer. Other data were collected outdoors and of a rat esophagus, demonstrating the sensor’s ability to resolve spectral signatures in both standard outdoor lighting and environmental conditions, as well as in fluorescence spectroscopy.

Persistent surveillance and collection of airborne intelligence, surveillance and reconnaissance information is critical in today’s warfare against terrorism. High resolution imagery in visible and infrared bands provides valuable detection capabilities based on target shapes and temperatures. However, the spectral resolution provided by a hyperspectral imager adds a spectral dimension to the measurements, leading to additional tools for detection and identification of targets, based on their spectral signature. The Telops Hyper-Cam sensor is an interferometer-based imaging system that enables the spatial and spectral analysis of targets using a single sensor. It is based on the Fourier-transform technology yielding high spectral resolution and enabling high accuracy radiometric calibration. It provides datacubes of up to 320×256 pixels at spectral resolutions as fine as 0.25 cm^-1. The LWIR version covers the 8.0 to 11.8 μm spectral range. The Hyper-Cam has been recently used for the first time in two compact airborne platforms: a bellymounted gyro-stabilized platform and a gyro-stabilized gimbal ball. Both platforms are described in this paper, and successful results of high-altitude detection and identification of targets, including industrial plumes, and chemical spills are presented.

Remote gas detection and visualization provides vital information in scenarios involving chemical accidents, terrorist attacks or gas leaks. Previous work showed how imaging infrared spectroscopy can be used to assess the location, the dimensions, and the dispersion of a potentially hazardous cloud. In this work the latest developments of an infrared hyperspectral imager based on a Michelson interferometer in combination with a focal plane array detector are presented. The performance of the system is evaluated by laboratory measurements. The system was deployed in field measurements to identify industrial gas emissions. Excellent results were obtained by successfully identifying released gases from relatively long distances.

Remote sensing infrared characterization of rapidly evolving events generally involves the combination of a spectro-radiometer and infrared camera(s) as separated instruments. Time synchronization, spatial coregistration, consistent radiometric calibration and managing several systems are important challenges to overcome; they complicate the target infrared characterization data processing and increase the sources of errors affecting the final radiometric accuracy. MR-i is a dual-band Hyperspectal imaging spectro-radiometer, that combines two 256 x 256 pixels infrared cameras and an infrared spectro-radiometer into one single instrument. This field instrument generates spectral datacubes in the MWIR and LWIR. It is designed to acquire the spectral signatures of rapidly evolving events. The design is modular. The spectrometer has two output ports configured with two simultaneously operated cameras to either widen the spectral coverage or to increase the dynamic range of the measured amplitudes. Various telescope options are available for the input port. Recent platform developments and field trial measurements performances will be presented for a system configuration dedicated to the characterization of airborne targets.

The emergence of new infrared camouflage and countermeasure technologies in the context of military operations has paved the way to enhanced detection capabilities. Camouflage devices such as candles (or smoke bombs) and flares are developed to generate either large area or localized screens with very high absorption in the infrared. Similarly, soldier's camouflage devices such as clothing have evolved in design to dissolve their infrared characteristics with that of the background. In all cases, the analysis of the targets infrared images needs to be conducted in both multispectral and hyperspectral domains to assess their capability to efficiently provide visible and infrared camouflage. The Military University of Technology has conducted several intensive field campaigns where various types of smoke candles and camouflage uniforms were deployed in different conditions and were measured both in the multispectral and hyperspectral domains. Cooled broadband infrared cameras were used for the multispectral analysis whereas the high spectral, spatial and temporal resolution acquisition of these thermodynamic events was recorded with the Telops Hyper-Cam sensor. This paper presents the test campaign concept and the analysis of the recorded measurements.

A rotating direct vision prism, chromotomosynthetic imaging (CTI) system operating in the visible creates hyperspectral imagery by collecting a set of 2D images with each spectrally projected at a different rotation angle of the prism. Mathematical reconstruction techniques that have been well tested in the field of medical physics are used to reconstruct the data to produce the 3D hyperspectral image. The instrument operates with a 100 mm focusing lens in the spectral range of 400-900 nm with a field of view of 71.6 mrad and angular resolution of 0.8-1.6 μrad. The spectral resolution is 0.6 nm at the shortest wavelengths, degrading to over 10 nm at the longest wavelengths. Measurements using a pointlike target show that performance is limited by chromatic aberration. The accuracy and utility of the instrument is assessed by comparing the CTI results to spatial data collected by a wideband image and hyperspectral data collected using a liquid crystal tunable filter (LCTF). The wide-band spatial content of the scene reconstructed from the CTI data is of same or better quality as a single frame collected by the undispersed imaging system with projections taken at every 1°. Performance is dependent on the number of projections used, with projections at 5° producing adequate results in terms of target characterization. The data collected by the CTI system can provide spatial information of equal quality as a comparable imaging system, provide high-frame rate slitless 1-D spectra, and generate 3-D hyperspectral imagery which can be exploited to provide the same results as a traditional multi-band spectral imaging system. While this prototype does not operate at high speeds, components exist which will allow for CTI systems to generate hyperspectral video imagery at rates greater than 100 Hz. The instrument has considerable potential for characterizing bomb detonations, muzzle flashes, and other battlefield combustion events.