The Experts below are selected from a list of 186522 Experts worldwide ranked by ideXlab platform
Christelloic Tisse - One of the best experts on this subject based on the ideXlab platform.
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single image based solution for optics temperature dependent Nonuniformity correction in an uncooled long wave infrared camera
Optics Letters, 2014Co-Authors: Christelloic TisseAbstract:In this Letter, we propose an efficient and accurate solution to remove temperature-dependent Nonuniformity effects introduced by the imaging optics. This single-image-based approach computes optics-related fixed pattern noise (FPN) by fitting the derivatives of correction model to the gradient components, locally computed on an infrared image. A modified bilateral filtering algorithm is applied to local pixel output variations, so that the refined gradients are most likely caused by the Nonuniformity associated with optics. The estimated bias field is subtracted from the raw infrared imagery to compensate the intensity variations caused by optics. The proposed method is fundamentally different from the existing Nonuniformity correction (NUC) techniques developed for focal plane arrays (FPAs) and provides an essential image processing functionality to achieve completely shutterless NUC for uncooled long-wave infrared (LWIR) imaging systems.
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shutterless solution for simultaneous focal plane array temperature estimation and Nonuniformity correction in uncooled long wave infrared camera
Applied Optics, 2013Co-Authors: Christelloic TisseAbstract:In uncooled long-wave infrared (LWIR) microbolometer imaging systems, temperature fluctuations of the focal plane array (FPA) result in thermal drift and spatial Nonuniformity. In this paper, we present a novel approach based on single-image processing to simultaneously estimate temperature variances of FPAs and compensate the resulting temperature-dependent Nonuniformity. Through well-controlled thermal calibrations, empirical behavioral models are derived to characterize the relationship between the responses of microbolometer and FPA temperature variations. Then, under the assumption that strong dependency exists between spatially adjacent pixels, we estimate the optimal FPA temperature so as to minimize the global intensity variance across the entire thermal infrared image. We make use of the estimated FPA temperature to infer an appropriate Nonuniformity correction (NUC) profile. The performance and robustness of the proposed temperature-adaptive NUC method are evaluated on realistic IR images obtained by a 640×512 pixels uncooled LWIR microbolometer imaging system operating in a significantly changed temperature environment.
V G Karpov - One of the best experts on this subject based on the ideXlab platform.
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blocking thin film nonuniformities photovoltaic self healing
Applied Physics Letters, 2004Co-Authors: Y Roussillon, Dean M Giolando, Diana Shvydka, Alvin D. Compaan, V G KarpovAbstract:An approach is developed to block the effects of lateral nonuniformities in thin-film semiconductor structures. The Nonuniformity modulates the surface photovoltage distribution. When exposed to light and immersed in a proper electrolyte, this distribution will generate laterally nonuniform electrochemical reactions. Such treatments result in a nonuniform interfacial layer that balances the original Nonuniformity. This approach has been implemented for CdTe/CdS photovoltaic devices, in which it improved the device efficiency from 1%–3% to 11%–12%.
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The mesoscale physics of large-area photovoltaics
3rd World Conference onPhotovoltaic Energy Conversion 2003. Proceedings of, 2003Co-Authors: V G Karpov, Diana Shvydka, Y. Roussilon, Alvin D. CompaanAbstract:Recent findings make the physics of large-area thin- film devices a distinctive field of its own, considerably different from that of microelectronics. We show that (i) large-area thin-film photovoltaic (PV) devices are intrinsically nonuniform in the lateral directions, (ii) the Nonuniformity spans over microscopically large dimensions, which can vary dramatically (from microns to meters) depending on light intensity and bias, and (iii) the Nonuniformity significantly impacts the device performance and stability. Our understanding suggests the concept of interfacial layer that blocks the Nonuniformity effects and can be applied photo-electrochemically. This concept is experimentally verified.
A N Kuchko - One of the best experts on this subject based on the ideXlab platform.
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spin wave interferometer employing a local Nonuniformity of the effective magnetic field
Journal of Applied Physics, 2007Co-Authors: S V Vasiliev, V V Kruglyak, M L Sokolovskii, A N KuchkoAbstract:We have investigated scattering of exchange spin waves by a model Nonuniformity of the effective magnetic field. In particular, certain profiles of the Nonuniformity are characterized by a total transmission of the spin wave intensity while inducing large shifts to the phase of transmitted spin waves. These properties are discussed in the context of potential application within a spin wave logic device—a spin wave interferometer containing such a Nonuniformity in one of its branches. We demonstrate limitations imposed upon the size and the speed of operation of such a device by a requirement that it be controlled by an external uniform magnetic field.
Edward Yi Chang - One of the best experts on this subject based on the ideXlab platform.
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study of inherent gate coupling Nonuniformity of inas gasb vertical tfets
IEEE Transactions on Electron Devices, 2016Co-Authors: Yuping Zeng, Chen-yen Chang, Chenming Hu, Edward Yi ChangAbstract:An electrostatic Nonuniformity in the cantilever vertical tunneling FETs intrinsically exists in the InAs/GaSb junction to InAs cantilever transition region. The effects of the coupling ratio (CR) Nonuniformity are investigated in this paper. The results show that the switching characteristics are degraded by the CR Nonuniformity, especially in the case of large InAs/GaSb band offset. This paper also reveals that the Nonuniformity in InAs/GaSb vertical tunneling FETs can be mitigated with the optimized band offset of heterojunction, scaling of oxide thickness, and acute angle etching profile.
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Study of Inherent Gate Coupling Nonuniformity of InAs/GaSb Vertical TFETs
IEEE Transactions on Electron Devices, 2016Co-Authors: Yuping Zeng, Chen-yen Chang, Chenming Hu, Edward Yi ChangAbstract:An electrostatic Nonuniformity in the cantilever vertical tunneling FETs intrinsically exists in the InAs/GaSb junction to InAs cantilever transition region. The effects of the coupling ratio (CR) Nonuniformity are investigated in this paper. The results show that the switching characteristics are degraded by the CR Nonuniformity, especially in the case of large InAs/GaSb band offset. This paper also reveals that the Nonuniformity in InAs/GaSb vertical tunneling FETs can be mitigated with the optimized band offset of heterojunction, scaling of oxide thickness, and acute angle etching profile.
Y Roussillon - One of the best experts on this subject based on the ideXlab platform.
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blocking thin film nonuniformities photovoltaic self healing
Applied Physics Letters, 2004Co-Authors: Y Roussillon, Dean M Giolando, Diana Shvydka, Alvin D. Compaan, V G KarpovAbstract:An approach is developed to block the effects of lateral nonuniformities in thin-film semiconductor structures. The Nonuniformity modulates the surface photovoltage distribution. When exposed to light and immersed in a proper electrolyte, this distribution will generate laterally nonuniform electrochemical reactions. Such treatments result in a nonuniform interfacial layer that balances the original Nonuniformity. This approach has been implemented for CdTe/CdS photovoltaic devices, in which it improved the device efficiency from 1%–3% to 11%–12%.
