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Yaniv R.,Open University of Israel | Yair Y.,Open University of Israel | Price C.,Tel Aviv University | Bor J.,Geodetic Observatory | And 5 more authors.
Journal of Atmospheric and Solar-Terrestrial Physics | Year: 2014

Optical observations of 66 sprites, using a calibrated commercial CCD camera, were conducted in 2009-2010 and 2010-2011 winter seasons as part of the ILAN (Imaging of Lightning And Nocturnal flashes) campaign in the vicinity of Israel and the eastern Mediterranean. We looked for correlations between the properties of parent lightning (specifically, the charge moment change; CMC) to the properties of column sprites, such as the measured radiance, the length and the number of column elements in each sprite event. The brightness of sprites positively correlates with the CMC (0.7) and so does the length of sprite elements (0.83). These results are in agreement with previous studies, and support the QE model of sprite generation. © 2013 Elsevier Ltd. Source


Rozenstein O.,Ben - Gurion University of the Negev | Devir A.,IARD Sensing Solutions Ltd. | Karnieli A.,Ben - Gurion University of the Negev
Remote Sensing | Year: 2014

Spectrometer calibration and measurements of spectral radiance are often required when performing ground, aerial, and space measurements. While calibrating a spectrometer in the field using an integrating sphere is practically unachievable, calibration against a quartz halogen (QH) lamp is a quite easy and feasible option. We describe a calibration protocol whereby a professional QH lamp, operating with a stabilized current source, is first calibrated in the laboratory against a US National Institute of Standards and Technology (NIST) traceable integrating sphere and, then, used for the field calibration of a spectrometer before a ground or airborne campaign. Another advantage of the lamp over the integrating sphere is its ability to create a continuous calibration curve at the spectrometer resolution, while the integrating sphere is calibrated only for a few discrete wavelengths. A calibrated lamp could also be used for a secondary continuous calibration of an un-calibrated integrating sphere. © 2014 by the authors. Source


Kellarev A.,IARD Sensing Solutions Ltd. | Sheffer D.,IARD Sensing Solutions Ltd.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

The subject of this article is implementation of terahertz remote sensing for detection and imaging of concealed objects from distances of several metres. Many materials used for packaging and clothing are partially transparent in the spectral range 0.1 - 10 THz. The transparency property can be utilised to detect objects concealed by the materials, which are often opaque in other spectral regions. This can be achieved by detecting the radiation from these objects through the use of an appropriate detector, which is sensitive at THz frequencies. The radiation from the concealed objects can be either self-emitted or reflected. The use of THz remote sensing is being pursued in IARD by both theoretical and practical approaches. The article contains a short review on the detectors, sources and components, which can be used for remote sensing systems operating at THz frequencies, and describes energy calculations and system design considerations. Characteristic and exemplar performance of the components, which are being used in IARD, is presented. The article then describes prototypes of a passive THz radiometer and an active THz system, which were built in IARD. Performance characteristics of both systems are described. The measurement results of the optical properties of various materials are presented as well as examples of images obtained by the active THz system. © 2010 SPIE. Source


Devir A.D.,IARD Sensing Solutions Ltd. | Bushlin Y.,IARD Sensing Solutions Ltd. | Mendelewicz I.,IARD Sensing Solutions Ltd. | Lessin A.B.,IARD Sensing Solutions Ltd. | Engel M.,IARD Sensing Solutions Ltd.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

Knowledge regarding the processes involved in blasts and detonations is required in various applications, e.g. missile interception, blasts of high-explosive materials, final ballistics and IED identification. Blasts release large amount of energy in short time duration. Some part of this energy is released as intense radiation in the optical spectral bands. This paper proposes to measure the blast radiation by a fast multispectral radiometer. The measurement is made, simultaneously, in appropriately chosen spectral bands. These spectral bands provide extensive information on the physical and chemical processes that govern the blast through the time-dependence of the molecular and aerosol contributions to the detonation products. Multi-spectral blast measurements are performed in the visible, SWIR and MWIR spectral bands. Analysis of the cross-correlation between the measured multi-spectral signals gives the time dependence of the temperature, aerosol and gas composition of the blast. Farther analysis of the development of these quantities in time may indicate on the order of the detonation and amount and type of explosive materials. Examples of analysis of measured explosions are presented to demonstrate the power of the suggested fast multispectral radiometric analysis approach. © 2011 SPIE. Source


Sabati T.Y.,IARD Sensing Solutions Ltd. | Devir A.D.,IARD Sensing Solutions Ltd. | Lessin A.B.,IARD Sensing Solutions Ltd. | Engel M.,IARD Sensing Solutions Ltd. | Bushlin Y.,IARD Sensing Solutions Ltd.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

Blasts and detonations release large amount of energy in short time duration. Some of this energy is released in the form of intense radiation in the whole optical spectrum. In most cases, the study of blasts is mainly based on cameras that document the event in the visible range at very high frame rates. We propose to complement this mode of blast analysis with a fast measurement of the radiation emitted by the blast at different spectral bands simultaneously. A fast multispectral radiometer that operates in the proper spectral bands provides extensive information on the physical processes that govern the blast. This information includes the time dependence of the temperature, aerosol and gas composition of the blast, as well as minute changes in the expansion of the blast - changes that may indicate the order of the detonation. This paper presents the new methodology and instrumentation of fast multispectral blast radiometry and shows analysis of measured explosions that demonstrate the power of this methodology. © 2010 Copyright SPIE - The International Society for Optical Engineering. Source

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