Browsing by Subject "Infrared imaging"
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Item Open Access An analysis for the broad-band absorption enhancement using plasmonic structures on uncooled infrared detector pixels(SPIE, 2012-05) Lüleç, S. Z.; Küçük, S. E.; Battal, Enes; Okyay, Ali Kemal; Tanrıkulu, M. Y.; Akın, T.This paper introduces an analysis on the absorption enhancement in uncooled infrared pixels using resonant plasmon modes in metal structures, and it reports, for the first time in literature, broad-band absorption enhancement using integrated plasmonic structures in microbolometers for unpolarized long-wave IR detection. Different plasmonic structures are designed and simulated on a stack of layers, namely gold, polyimide, and silicon nitride in order to enhance absorption at the long-wave infrared. The simulated structures are fabricated, and the reflectance measurements are conducted using an FTIR Ellipsometer in the 8-12 μm wavelength range. Finite difference time domain (FDTD) simulations are compared to experimental measurement results. Computational and experimental results show similar spectral reflection trends, verifying broad-band absorption enhancement in the spectral range of interest. Moreover, this paper computationally investigates pixel-wise absorption enhancement by plasmonic structures integrated with microbolometer pixels using the FDTD method. Special attention is given during the design to be able to implement the integrated plasmonic structures with the microbolometers without a need to modify the pre-determined microbolometer process flow. The optimized structure with plasmonic layer absorbs 84 % of the unpolarized radiation in the 8-12 μm spectral range on the average, which is a 22 % increase compared to a reference structure with no plasmonic design. Further improvement may be possible by designing multiply coupled resonant structures.Item Open Access Development and characterization of a megapixel SWIR imaging system(Bilkent University, 2022-01) Erdoğan, MustafaThis thesis aims to develop a megapixel SWIR camera electronics and share the knowledge that has been acquired during the design phase as a detailed document that explains the theory and design steps to stand as a reference for academic researchers and engineers who work in this field. Valuable information from many different resources including books, presentations, technical articles, theses, etc. has been compiled and presented in this thesis following the design order. This thesis reviews the nature of light and its detection mechanisms and then concentrates on the idea of developing a product to detect light in the SWIR band. The sensors to detect light in the SWIR band are designed and manufactured in NANOTAM. There is a need to develop both hardware and software to process the sensor outputs which carry information about the captured image to generate a meaningful and useful set of data to be displayed. The objective is to come up with an imaging system that uses the in-house manufactured sensors and digitally visualizes the SWIR band with the best per-formance possible. The components that will make up the imaging system are examined thoroughly to be able to inherit correct design procedures and go for the best performance while preventing costly over-design. Different image sensor types such as CCD, CMOS, InGaAs, etc., and their characteristics and requirements are studied in detail. Analog Front End electronics are designed to add the lowest possible noise and thus degrading the sensor performance minimally. Other electronic circuits such as Thermoelectric Cooler controller, power regulation, FPGA electronics, etc. are designed to meet required operations without causing dis-turbance to Analog Front End electronics. Designs are carried out by abiding by correct PCB design practices which are addressed in this thesis. This way, it is made sure that the sensor performance, which is the limiting factor, is not degraded by the external electronics.Item Open Access LWIR all-atomic layer deposition ZnO bilayer microbolometer for thermal imaging(SPIE, 2017) Poyraz, M.; Gorgulu, K.; Sisman, Z.; Tanrikulu, M. Y.; Okyay, Ali KemalWe propose an all-ZnO bilayer microbolometer, operating in the long-wave infrared regime that can be implemented by consecutive atomic layer deposition growth steps. Bilayer design of the bolometer provides very high absorption coefficients compared to the same thickness of a single ZnO layer. High absorptivity of the bilayer structure enables higher performance (lower noise equivalent temperature difference and time constant values) compared to single-layer structure. We observe these results computationally by conducting both optical and thermal simulations. © 2017 Society of Photo-Optical Instrumentation Engineers (SPIE).Item Open Access Mean-shift tracking of moving objects using multi-dimensional histograms(Society of Photo-Optical Instrumentation Engineers (SPIE), 2004-04) Cüce, Halil I.; Çetin, A. EnisIn this paper, a moving object tracking algorithm for infrared image sequences is presented. The tracking algorithm is based on the mean-shift tracking method which is based on comparing the histograms of moving objects in consecutive image frames. In video obtained after visible light, the color histogram of the object is used for tracking. In forward looking infrared image sequences, the histogram is constructed not only from the pixel values but also from a highpass filtered version of the original image. The reason behind the use of highpass filter outputs in histogram construction is to capture structural nature of the moving object. Simulation examples are presented.Item Open Access Simultaneous extraction of geometry and surface properties of targets using simple infrared sensors(SPIE, 2004) Aytaç, T.; Barshan, B.We investigate the use of low-cost infrared (IR) sensors for the simultaneous extraction of geometry and surface properties of commonly encountered features or targets in indoor environments, such as planes, corners, and edges. The intensity measurements obtained from such sensors are highly dependent on the location, geometry, and surface properties of the reflecting target in a way that cannot be represented by a simple analytical relationship, therefore complicating the localization and recognition process. We propose the use of angular intensity scans and present an algorithm to process them to determine the geometry and the surface type of the target and estimate its position. The method is verified experimentally with planes, 90-deg corners, and 90-deg edges covered with aluminum, white cloth, and Styrofoam packaging material. An average correct classification rate of 80% of both geometry and surface over all target types is achieved and targets are localized within absolute range and azimuth errors of 1.5 cm and 1.1 deg, respectively. Taken separately, the geometry and surface type of targets can be correctly classified with rates of 99 and 81%, respectively, which shows that the geometrical properties of the targets are more distinctive than their surface properties, and surface determination is the limiting factor. The method demonstrated shows that simple IR sensors, when coupled with appropriate processing, can be used to extract substantially more information than that for which such devices are commonly employed. © 2004 Society of Photo-Optical Instrumentation Engineers.