This PDF file contains the front matter associated with SPIE Proceedings Volume 9481 including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

Integration and pixel scaling are enabling trends for low-cost, small form-factor, light-weight, and low-power camera systems across all optical frequency bands. Integration allows on-chip implementations of optical functionalities, e.g., polarization, color and spectral selectivity, which were previously achieved using bulky external components (e.g., prisms, filter wheels). Wavelength-size pixels require focusing and guiding of light at the pixel-level (e.g., micro-lenses, light guides), which was not necessary for larger pixels. On-chip integration of optical functionalities and pixel-level light control is often based on miniaturized versions of conventional optical components. These components derive their functionality from material properties or shapes, but do not lend themselves well to integration or scale to wavelengthsize pixels. Here, I present an overview of innovative integrated optical devices that overcome the problems associated with the integration and scaling of conventional components. They are enabled by scaling of imager and focal plane array technology, and by advanced nanofabrication. Wafer-scale processing and nanofabrication have made nano-scale patterning possible, while recent discoveries regarding the optical properties of nano-patterned structures have opened up important opportunities to develop ultra-compact photonic devices. I discuss design implementations for the visible (VIS) and infrared (IR) wavelength bands, including VIS integrated color pixels (ICPs) in a complementary metal-oxide semiconductor (CMOS) technology with geometry-based color filters, micro-lens functionality based on planar nanoaperture designs, and metal-based spectral filters for mid-wave IR (MWIR) multispectral imaging that can be implemented using standard nanofabrication methods. The devices are planar and/or ultra-thin, rely on processcompatible materials only, and derive their functionality from sub-wavelength geometry design.

Banpil Photonics has developed a novel InGaAs based photodetector array for Short-Wave Infrared (SWIR) imaging, for the most demanding security, defense, and machine vision applications. These applications require low noise from both the detector and the readout integrated circuit arrays. In order to achieve high sensitivity, it is crucial to minimize the dark current generated by the photodiode array. This enables the sensor to function in extremely low light situations, which enables it to successfully exploit the benefits of the SWIR band. In addition to minimal dark current generation, it is essential to develop photodiode arrays with higher operating temperatures. This is critical for reducing the power consumption of the device, as less energy is spent in cooling down the focal plane array (in order to reduce the dark current). We at Banpil Photonics are designing, simulating, fabricating and testing SWIR InGaAs arrays, and have achieved low dark current density at room temperature. This paper describes Banpil’s development of the photodetector array. We also highlight the fabrication technique used to reduce the amount of dark current generated by the photodiode array, in particular the surface leakage current. This technique involves the deposition of strongly negatively doped semiconductor material in the area between the pixels. This process reduces the number of dangling bonds present on the edges of each pixel, which prevents electrons from being swept across the surface of the pixels. This in turn drastically reduces the amount of surface leakage current at each pixel, which is a major contributor towards the total dark current. We present the optical and electrical characterization data, as well as the analysis that illustrates the dark current mechanisms. Also highlighted are the challenges and potential opportunities for further reduction of dark current, while maintaining other parameters of the photodiode array, such as size, weight, temperature of peak performance (lowest dark current), and power consumption.

A deposition technique has been developed to create thin metal surfaces composed of functionalized fluorescent silver nanoparticles on top of glass or plastic substrates. Deposition is controlled through excitation of nanoparticles via a confocal microscope, allowing for rapid surface formation, high resolution patterning and convenient imaging. The functionalization of these nanoparticles can be tailored to a desired application. Initial investigations have demonstrated that surfaces can be designed to mimic the glucan and mannan layers of a fungal cell wall, which in turn can be used to stimulate and study responses from human immune cells.

For surveillance and reconnaissance applications in the short-wave infrared (SWIR) spectral range, the imaging systems have to cope with usually very low photon flux densities. Thus, dark-current and noise characteristics of the focal plane array (FPA) are demanding. On the other hand, the challenge of detecting extremely low photocurrents can be mitigated by utilizing an internal gain as provided by avalanche photodiodes (APDs). Fraunhofer IAF has recently started the development of InGaAs-based SWIR detectors. We report on the current development status covering design considerations, epitaxy, process technology and electro-optical characterization. Detector structures based on both, classical InGaAs PIN homojunction diodes as well as InGaAs/InAlAs APDs in separated-absorption-grading-charge-and-multiplication layer heterostructures, have been grown by molecular beam epitaxy on InP. Diodes structures were fabricated with a dry-etch mesa process and a subsequent dielectric passivation of the mesa sidewalls. High-resolution FPAs with 640 x 512 pixels and a 15 μm pixel pitch based on PIN diodes have been assembled to a SWIR camera system in cooperation with AIM Infrarot-Module GmbH. Design variations, in particular for the APDs, were assisted by band-edge-profile simulations. APD test structures as well as fan-out hybrids have been characterized, revealing gain values larger than 300 at room temperature.

Challenges and opportunities of ultraviolet (UV), visible (VIS) and near-infrared (NIR) light imaging technologies are overviewed in this paper. For light detectors and image sensors for UV/VIS/NIR imaging, it is required that they have high sensitivity for wide spectral light waveband or targeted narrow waveband as well as the high stability of light sensitivity toward UV light based on cost effective technology. Wide spectral response, high sensitivity and high stability advanced Si photodiode (PD) pn junction formation technology based on the flattened Si surface and high transmittance on-chip optical filter formation technology were developed. A linear photodiode array (PDA), wide dynamic range and ultrahigh speed CMOS image sensors employing the developed technology were fabricated and their advanced performances are described in this paper.

The size, weight and power (SWaP) of state of the art infrared focal plane arrays are limited by the pixel size approaching the diffraction limit. We investigate a novel detector architecture which allows improvements in detectivity by shrinking the absorber volume while maintaining high quantum efficiency and wide field of view (FOV). It has been previously shown that the Nanopillar Optical Antenna (NOA) utilizes 3D plasmonic modes to funnel light into a subwavelength nanopillar absorber. We show detailed electro-optical simulations for the NOA-nBn architecture for overcoming generation recombination current with suitable surface passivation to achieve background limited infrared performance.

In this work, we studied a mid-infrared modulating retro-reflector (MRR) design that is GaAs-based because of the flexibility to monolithically incorporate reflective optics along with quantum well modulator region. Using solid-source molecular beam epitaxy, we produced MRR devices, where the GaAs quantum well(s) in the modulator region contained Al_xGa_1-xAs barriers to tune the wavelength selectivity beyond three microns. The width of the quantum well was also adjusted in order to achieve free electron absorption within the confined energy subbands and modified by way of the quantum confined Stark effect. When the applied electric field varies in polarity, intensity, or frequency, the fabricated MRRs behave as an optional shutter--absorbing or transmitting the incident mid-infrared energy depending on the applied field. Our work shows that the ability for the modulating region to effectively act as a shutter for mid-infrared radiation depends on the number of cascading quantum wells, though increasing the number of wells directly increases the overall thickness of the modulating region and adversely affects the reflected power of the mid-infrared modulated beam. The shutter operation was achieved by applying an alternating square bias across the QWM region, and the speed at which the quantum wells switch from absorbing to non-absorbing was dependent on the physical size of the device. Increasing the physical size increases the associated device capacitance. The maximum achievable contrast ratio for these devices is calculated to be 1.6:1 for applied voltages between 12V and 25V.

This paper presents a hybrid technique for measuring conversion gain that blends spatial and temporal information, allowing users to calculate an accurate conversion gain with little knowledge of sensor defects. It blends a single pixel method with multiple pixel methods. We present measured data from a visible CMOS image sensor using two multiple pixel methods and the hybrid method. Additionally, we provide arguments for validity of the hybrid method. To our knowledge, this is the first report of this technique. Conversion gain (e-/DN) directly relates measured digital numbers (DN) to input-referred electrons (e-) for an image sensor. Conversion gain can be directly measured by considering the sensor under varying illumination states in coordination with Poisson statistics. Typically, there are two approaches: measure a single pixel over time or measure a group of pixels at one point in time after correcting for gain non-uniformity. The plotted statistics from these measurements are called either mean-variance or photon-transfer curves. The measurement of a single pixel is relatively straightforward and requires collection of many consecutive frames to get meaningful statistics not dominated by thermal noise. The data volume for an accurate single-pixel measurement can become unwieldy in terms of number of frames required. This is especially true for large format image sensors. In contrast, the measurement of a group of pixels requires fewer consecutive frames, but needs non-uniformity adjustments to correctly calculate statistics.

The Advanced Computational Sensors Team at the Johns Hopkins University Applied Physics Laboratory and the Johns Hopkins University Department of Electrical and Computer Engineering has been developing advanced readout integrated circuit (ROIC) technology for more than 10 years with a particular focus on the key challenges of dynamic range, sampling rate, system interface and bandwidth, and detector materials or band dependencies. Because the pixel array offers parallel sampling by default, the team successfully demonstrated that adding smarts in the pixel and the chip can increase performance significantly. Each pixel becomes a smart sensor and can operate independently in collecting, processing, and sharing data. In addition, building on the digital circuit revolution, the effective well size can be increased by orders of magnitude within the same pixel pitch over analog designs. This research has yielded an innovative class of a system-on-chip concept: the Flexible Readout and Integration Sensor (FRIS) architecture. All key parameters are programmable and/or can be adjusted dynamically, and this architecture can potentially be sensor and application agnostic. This paper reports on the testing and evaluation of one prototype that can support either detector polarity and includes sample results with visible, short-wavelength infrared (SWIR), and long-wavelength infrared (LWIR) imaging.

The present generation of mobile handheld devices comes equipped with a large number of sensors. The key sensors include the Ambient Light Sensor, Proximity Sensor, Gyroscope, Compass and the Accelerometer. Many mobile applications are driven based on the readings obtained from either one or two of these sensors. However the presence of multiple-sensors will enable the determination of more detailed activities that are carried out by the user of a mobile device, thus enabling smarter mobile applications to be developed that responds more appropriately to user behavior and device usage. In the proposed research we use recent advances in machine learning to fuse together the data obtained from all key sensors of a mobile device. We investigate the possible use of single and ensemble classifier based approaches to identify a mobile device’s behavior in the space it is present. Feature selection algorithms are used to remove non-discriminant features that often lead to poor classifier performance. As the sensor readings are noisy and include a significant proportion of missing values and outliers, we use machine learning based approaches to clean the raw data obtained from the sensors, before use. Based on selected practical case studies, we demonstrate the ability to accurately recognize device behavior based on multi-sensor data fusion.

The evolution of infrared (IR) imaging sensor technology for defense market has played an important role in developing commercial market, as dual use of the technology has expanded. In particular, technologies of both reduction in pixel pitch and vacuum package have drastically evolved in the area of uncooled Long-Wave IR (LWIR; 8-14 μm wavelength region) imaging sensor, increasing opportunity to create new applications. From the macroscopic point of view, the uncooled LWIR imaging market is divided into two areas. One is a high-end market where uncooled LWIR imaging sensor with sensitivity as close to that of cooled one as possible is required, while the other is a low-end market which is promoted by miniaturization and reduction in price. Especially, in the latter case, approaches towards consumer market have recently appeared, such as applications of uncooled LWIR imaging sensors to night visions for automobiles and smart phones. The appearance of such a kind of commodity surely changes existing business models. Further technological innovation is necessary for creating consumer market, and there will be a room for other companies treating components and materials such as lens materials and getter materials and so on to enter into the consumer market.

CMOS image sensor manufacturer, AWAIBA, is providing the world’s smallest digital camera modules to the world market for minimally invasive surgery and one time use endoscopic equipment. Based on the world’s smallest digital camera head and the evaluation board provided to it, the aim of this paper is to demonstrate an advanced fast response dynamic control algorithm of the illumination LED source coupled to the camera head, over the LED drivers embedded on the evaluation board. Cost efficient and small size endoscopic camera modules nowadays embed minimal size image sensors capable of not only adjusting gain and exposure time but also LED illumination with adjustable illumination power. The LED illumination power has to be dynamically adjusted while navigating the endoscope over changing illumination conditions of several orders of magnitude within fractions of the second to guarantee a smooth viewing experience. The algorithm is centered on the pixel analysis of selected ROIs enabling it to dynamically adjust the illumination intensity based on the measured pixel saturation level. The control core was developed in VHDL and tested in a laboratory environment over changing light conditions. The obtained results show that it is capable of achieving correction speeds under 1 s while maintaining a static error below 3% relative to the total number of pixels on the image. The result of this work will allow the integration of millimeter sized high brightness LED sources on minimal form factor cameras enabling its use in endoscopic surgical robotic or micro invasive surgery.

Nowadays, the number and capacity of very high resolution optical satellites grows permanently, so the access to very high resolution space images is not any more a problem. The use of Geographic Information Systems (GISs) together with Remote Sensing became important. With the increased ground resolution a competition to aerial images exist. For the generation of topographic maps, today available as GIS, the accuracy and the information content - what elements can be identified in the image - are important. Both may limit the presentation scale of topographic maps. As horizontal accuracy 0.25mm up to 0.3mm in the map scale are accepted. The required information content is more complicate. The object details to be presented in topographic maps vary from area to area which is based on the planned and unplanned areas. In this study, images from IRS-1C, Kompsat-1, SPOT 5, OrbView-3, IKONOS, QuickBird and WorldView-1 have been used for topographic mapping. For this reason, Zonguldak test fields are an important area for applications of the high resolution imageries. The details which can be identified in the space images dominantly depends upon the ground resolution, available as ground sampling distance (GSD). In this study, high resolution imageries have been tested depending on the GSD and corresponding to the map scales for updating GIS database.

Due to the richness on high frequency components, hyperspectral image (HSI) is more sensitive to distortion like aliasing. Many methods aiming at removing such distortion have been proposed. However, seldom of them are suitable to HSI, due to low spatial resolution characteristic of HSI. Fortunately, HSI contains plentiful spectral information, which can be exploited to overcome such difficulties. Motivated by this, we proposed an aliasing removing method for HSI. The major differences between proposed and current methods is that proposed algorithm is able to utilize fractal structure information, thus the dilemma originated from low-resolution of HSI is solved. Experiments on real HSI data demonstrated subjectively and objectively that proposed method can not only remove annoying visual effect brought by aliasing, but also recover more high frequency component.

A low noise low power 512×256 readout integrated circuit (ROIC) based on Capacitance Trans-impedance Amplifier (CTIA) was designed in this paper. The ROIC with 30μm pixel-pitch and 70 fF integrated capacitance as normal structure and test structure capacitance from 5 to 60 fF, was fabricated in 0.5μm DPTM CMOS process. The results showed that output voltage was larger than 2.0V and power consumption was about 150mW, output ROIC noise was about 3.6E-4V which equivalent noise was 160e-, and the test structure noise was from 20e- to 140 e-. Compared the readout noises in Integration Then Readout (ITR) mode and Integration While Readout (IWR) mode, it indicated that in IWR mode, readout noise comes mainly from both integration capacitance and sampling capacitance, while in ITR mode, readout noise comes mostly from sampling capacitance. Finally the ROIC was flip-chip bonded with Indium bumps to extended wavelength InGaAs detectors with cutoff wavelength 2.5μm at 200K. The peak detectivity exceeded 5E11cmHz^1/2/w with 70nA/cm² dark current density at 200K.

For safe driving, it is important for driver to check traffic conditions such as traffic lights, or traffic signs as early as soon. If on-vehicle camera takes image of important objects to understand traffic conditions from long distance and shows these to driver, driver can understand traffic conditions earlier. To take image of long distance objects clearly, the focal length of camera must be long. When the focal length is long, on-vehicle camera doesn’t have enough field of view to check traffic conditions. Therefore, in order to get necessary images from long distance, camera must have long-focal length and controllability of shooting direction. In previous study, driver indicates shooting direction on displayed image taken by a wide-angle camera, a direction controllable camera takes telescopic image, and displays these to driver. However, driver uses a touch panel to indicate the shooting direction in previous study. It is cause of disturb driving. So, we propose a telephoto camera system for driving support whose shooting direction is controlled by driver’s gaze to avoid disturbing drive. This proposed system is composed of a gaze detector and an active telephoto camera whose shooting direction is controlled. We adopt non-wear detecting method to avoid hindrance to drive. The gaze detector measures driver’s gaze by image processing. The shooting direction of the active telephoto camera is controlled by galvanometer scanners and the direction can be switched within a few milliseconds. We confirmed that the proposed system takes images of gazing straight ahead of subject by experiments.

A new electromagnetic induction imaging system is presented which is capable of imaging metallic samples of different conductivities. The system is based on a parallel LCR circuit made up of a cylindrical ferrite-cored coil and a capacitor bank. An AC current is applied to the coil, thus generating an AC magnetic field. This field is modified when a conductive sample is placed within the magnetic field, as a consequence of eddy current induction inside the sample. The electrical properties of the LCR circuit, including the coil inductance, are modified due to the presence of this metallic sample. Position-resolved measurements of these modifications should then allow imaging of conductive objects as well as enable their characterization. A proof-of-principle system is presented in this paper. Two imaging techniques based on Q-factor and resonant frequency measurements are presented. Both techniques produced conductivity maps of 14 metallic objects with different geometries and values of conductivity ranging from 0.54х10⁶ to 59.77х10⁶ S/m. Experimental results highlighted a higher sensitivity for the Q-factor technique compared to the resonant frequency one; the respective measurements were found to vary within the following ranges: ΔQ=[-11,-2]%, Δf=[-0.3,0.7]%. The analysis of the images, conducted using a Canny edge detection algorithm, demonstrated the suitability of the Q-factor technique for accurate edge detection of both magnetic and non-magnetic metallic samples.

The present generation of Ambient Light Sensors (ALS) of a mobile handheld device suffer from two practical shortcomings. The ALSs are narrow angle, i.e. they respond effectively only within a narrow angle of operation and there is a latency of operation. As a result mobile applications that operate based on the ALS readings could perform sub-optimally especially when operated in environments with non-uniform illumination. The applications will either adopt with unacceptable levels of latency or/and may demonstrate a discrete nature of operation. In this paper we propose a framework to predict the ambient illumination of an environment in which a mobile device is present. The predictions are based on an illumination model that is developed based on a small number of readings taken during an application calibration stage. We use a machine learning based approach in developing the models. Five different regression models were developed, implemented and compared based on Polynomial, Gaussian, Sum of Sine, Fourier and Smoothing Spline functions. Approaches to remove noisy data, missing values and outliers were used prior to the modelling stage to remove their negative effects on modelling. The prediction accuracy for all models were found to be above 0.99 when measured using R-Squared test with the best performance being from Smoothing Spline. In this paper we will discuss mathematical complexity of each model and investigate how to make compromises in finding the best model.

We report the observation of surface-enhanced Raman scattering (SERS) from a chemically etched ZnSe surface using 4-mercaptopyridine (4-MPy) as probe molecules. A thin film of ZnSe is grown by molecular beam epitaxy (MBE) and then etched using a strong acid. Protrusions of hemi-ellipsoidal nanoparticles are observed on the surface. Using the results of the Mie theory, we controlled the size of the nanoparticles to overlap significantly with maximum efficiency of near-field plasmon enhancement. In the Raman spectrum, we observe large enhancements of the a₁, b₁, and b₂ modes when 4-MPy molecules are adsorbed on the surface using a 514.5 nm laser for excitation, indicating strong charge-transfer contributions. An enhancement factor of (2×10⁶) is observed comparable to that of silver nanoparticles. We believe this large enhancement factor is an indication of the coupled contribution of several resonances. We propose that some combination of surface plasmon, charge transfer, band gap resonances are most likely the contributing factors in the observed Raman signal enhancement, since all three of these resonances lie close to the excitation wavelength.

Self-assembled In(Ga)As/GaAs quantum dot infrared photodetectors (QDIPs) have promising applications in the midwavelength infrared and long-wavelength infrared regions for various defense and space application purposes. It has been demonstrated that the performance of QDIPs has improved significantly by using architectures such as dots-in-awell, different combinational capping or post growth treatment with high energy hydrogen ions. In this work, we enhanced the electrical properties InGaAs/GaAs using high energy proton implantation. Irradiation with proton resulted suppression in field assisted tunnelling of dark current by three orders for implanted devices. Photoluminescence (PL) enhancement was observed up to certain dose of protons due to eradication of as-grown defects and non radiative recombination centers. In addition, peak detectivity (D*) increased up to two orders of magnitude from 6.1 x10⁸ to 1.0 × 10¹⁰ cm-Hz^1/2/W for all implanted devices.

In this report, we are comparing two different QDIP architectures capped with quaternary and ternary layer of different barrier thicknesses and effect of rapid thermal annealing on the device performances. Low temperature power dependent PL spectra exhibit a multimodal distribution of the QDs in all the heterostructures which has been confirmed by XTEM. High thermal stability up to 800°C i.e. minimum PL peak shift in terms of wavelength was observed in all quaternary coupled devices with annealing compared to ternary (it was up to 700°C) capped QDIP. The vertical strain propagating from underlying QDs prevents the inter-diffusion by maintaining a strain relaxed state. Minimum Dark current density was observed in quaternary capped QDIP with total capping thickness of 15nm and one order enhancement in detectivity compared to ternary. Quaternary capped QDIP with 12 nm total capping thickness was most red shifted and a peak spectral response was observed at 7.3μm. Compared to ternary all quaternary devices showed narrow spectrum with less than 20% spectral line-width. Quaternary capped QDIP with 15 nm total capping thickness was annealed and devices were fabricated using 2 step lithography process. For 750°C annealed QDIP a maximum operating temperature of 140K with 5-fold increase in photocurrent compared to other was observed.

The barrier enhanced InAs/GaSb long wavelength photodetectors were proved to have better performance. Our previous work showed a PBIN detector with an electron barrier inserted show significantly improved electrical performances compared to a PIN structure. To improve the quantum efficiency, Be-doping was employed to convert the conductivity of the long wavelength SL structure, the PN junction moves away from the B-I hetrostructure to the π-N interface which loses the barrier effect. Therefore, the hole barrier was needed to form a PBπBN structure. In this paper, both the abrupt and gradual hole barrier was designed without Al element to form a PBπBN structure. The gradual hole barrier was optimized to avoid the blocking of photo generated current, maximized the quantum efficiency. The R_maxA product of the PBπBN detector was measured to be 77 Ωcm² and the dark current density under -0.05V bias was measured to be 8.8×10^-4A/cm² at 80K. The quantum efficiency of gradual hole barrier detector was measured to be 27.2% at 10.6 μm and the quantum efficiency was slowly decreased under reverse bias. The result shows the gradual hole barrier efficiently eliminate the peak barrier in the electron band. The peak detectivity of this graded detector is calculated to be 9.46×10¹⁰cm.Hz^1/2.W^-1 at 10.6 μm.

An automated alignment optical system will greatly simplify alignment tasks, increase the flexibility and utility of reconfigurable optical systems, and allow for the quick and efficient set up distributed optical systems. In this work, we demonstrate automated alignment of a tilted and decentered focal lens using only focal plane imaging by exploiting the aberration effects caused by the misalignment. A Gaussian beam is passed through the lens with 4 degrees of freedom and onto a science camera. The deformation of the spot image is analyzed to determine the tilt and shift misalignments on the lens. Corrections based on these measurements are applied in closed loop to align the system. We discuss various techniques for mitigating measurement errors, characterizing the system and operating the control loop and present results from the experiment.

Attachment of quantum dots or fluorescent molecules to gold nanoparticles has a variety of optical labeling and sensory applications. In this study, we use both e-beam lithography and DNA origami to examine the fluorescence enhancement of fluorescent molecules and quantum dots with a systematic approach to understanding the contribution of gold nanoparticle size and interparticle spacing. The unique design of our patterns allows us to study the effects of size and spacing of the gold nanoparticles on the enhancement of fluorescence in one quick study with constant conditions – removing undesirable effects such as differences in concentration of quantum dots or other chemistry differences that plague multiple experiments. We also discuss the fluorescence and bonding of CdSe/ZnS quantum dots to both gold as well as DNA for use in self assembled DNA constructs. Specifically, bioconjugated CdSe/ZnS core/shell quantum dots were synthesized and functionalized with MPA using both traditional ligand exchange as well as newly developed in situ functionalization techniques used to increase the quantum yield of the quantum dots. We will present fluorescent images showing results of optimal size and spacing for fluorescence as well as demonstrating attachment chemistry of the quantum dots.

This paper discusses how GigE Vision® video interfaces – the technology used to transfer data from a camera or image sensor to a mission computer or display – help designers reduce the cost and complexity of military imaging systems, while also improving usability and increasing intelligence for end-users. The paper begins with a detailed review of video connectivity approaches commonly used in military imaging systems, followed by an overview on the GigE Vision standard. With this background, the design, cost, and performance benefits that can be achieved when employing GigE Vision-compliant video interfaces in a vetronics retrofit upgrade project are outlined.

There is enormous interest in detection of simple & complex odors by mean of electronic instrumentation. Specifically, our work focuses on creating derivatized-nanotube-based “electronic noses” for the detection and identification of gases, and other materials. We have grafted single-walled carbon nanotubes (SWNTs) with an array of electron-donating and electron withdrawing moieties and have characterized some of the physicochemical properties of the modified nanotubes. Gas sensing elements have been fabricated by spin coating the functionalized nanotubes onto interdigitated electrodes (IDE’s), creating an array of sensors. Each element in the sensor array can contain a different functionalized matrix. This facilitates the construction of chemical sensor arrays with high selectivity and sensitivity; a methodology that mimics the mammalian olfactory system. Exposure of these coated IDEs to organic vapors and the successful classification of the data obtained under DC monitoring, indicate that the system can function as gas sensors of high repeatability and selectivity for a wide range of common analytes. Since the detection of explosive materials is also of concern in this research, our next phase focuses on explosives such as, TNT, RDX, and Triacetone Triperoxide (TATP). Sensor data from individual detection are assessed on their own individual merits, after which they are amalgamated and reclassified to present each vapor as unique data point on a 2-dimensional map and with minimum loss of information. This approach can assist the nation's need for a technology to defeat IEDs through the use of methods that detect unique chemical signatures associated with explosive molecules and byproducts.

Because of a significant impact of the microbolometer array temperature on the infrared image quality, it is necessary to compensate the influence of the temperature on the NUC process. In the most common applications two approaches are used: the first is a stabilization of the microbolometer array temperature by a thermoelectric cooler, the second is updating correction coefficients obtained from reference source, for example a shutter [14]. Both of the most common approaches have theirs disadvantages. The first case needs a considerable amount of energy for temperature stabilisation. The second one needs a reference target and a mechanical procedure to place the target at the front of the detector. Additionally, during calibration the reference target is blocking radiation from the scene, thus interrupting measurements with the thermal camera. In the article a non-uniformity correction method is presented which allows to compensate for the influence of detector’s temperature drift. For this purpose, dependency between output signal value and the temperature of the detector array was investigated. Additionally the influence of the temperature on the Offset and Gain coefficients was measured. Presented method utilizes estimated dependency between output signal of detectors and their temperature. In the presented method, the dependency between output signal value and the temperature of the detector is estimated during time of starting detector. The coefficients are estimated for every pixel. In the article proposed method allows to compensate the influence of detectors temperature fluctuation and increase a time between shutter actuation process.

A novel high-sensitivity active pixel sensor (APS) with a variable threshold photodetector has been presented and for the first time, a simple SPICE model for the variable threshold photodetector is presented. Its SPICE model is in good agreement with measurements and is more simpler than the conventional model. The proposed APS has a gate/body-tied PMOSFET-type photodetector with an overlapping control gate that makes it possible to control the sensitivity of the proposed APS. It is a hybrid device composed of a metal-oxide-semiconductor field-effect transistor (MOSFET), a lateral bipolar junction transistor (BJT) and a vertical BJT. Using sufficient overlapping control gate bias to operate the MOSFET in inversion mode, the variable threshold photodetector allows for increasing the photocurrent gain by 10⁵ at low light intensities when the control gate bias is -3 V. Thus, the proposed APS with a variable threshold photodetector has better low-light-level sensitivity than the conventional APS operating mode, and it has a variable sensitivity which is determined by the control gate bias. The proposed sensor has been fabricated by using 0.35 μm 2-poly 4-metal standard complementary MOS (CMOS) process and its characteristics have been evaluated.