Norwegian Defence Research Establishment FFI

Horten, Norway

Norwegian Defence Research Establishment FFI

Horten, Norway
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Skauli T.,Norwegian Defence Research Establishment FFI
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2017

The current state of the art of specifying spectral imagers falls short of what is needed. Commercial datasheets do not adequately reflect the performance of hyperspectral imagers offered as standard products. In particular, imperfections such as coregistration error, noise performance and stray light are rarely well specified. A standardized way to specify spectral imagers would benefit both developers and users of such instruments. The paper reviews the many different characteristics that are needed to describe various aspects of imager performance, and discusses possible ways to form figures of merit relevant to application performance. In particular, the product of quantum efficiency, optics transmission and nominal throughput (étendue) is shown to be a good figure of merit for radiometric performance. A list of about 30 characteristics is suggested as a standard for a complete specification of spectral imagers. For some characteristics, notably coregistration, it is necessary to establish a standardized measurement methodology. © 2017 SPIE.


Myhrer T.,Norwegian Defence Research Establishment FFI | Aas P.,Norwegian Defence Research Establishment FFI
Neuroscience and Biobehavioral Reviews | Year: 2016

The threat of chemical warfare agents like nerve agents requires life saving measures of medical pretreatment combined with treatment after exposure. Pretreatment (pyridostigmine) may cause some side effects in a small number of individuals. A comprehensive research on animals has been performed to clarify effects on behavior. The results from these studies are far from unambiguous, since pyridostigmine may produce adverse effects on behavior in animals in relatively high doses, but not in a consistent way. Other animal studies have examined the potential of drugs like physostigmine, galantamine, benactyzine, trihexyphenidyl, and procyclidine, but they all produce marked behavioral impairment at doses sufficient to contribute to protection against a convulsant dose of soman. Attempts have also been made to develop a combination of drugs capable of assuring full protection (prophylaxis) against nerve agents. However, common to all combinations is that they at anticonvulsant doses cause behavioral deficits. Therefore, the use of limited pretreatment doses may be performed without marked side effects followed by post-exposure therapy with a combination of drugs. © 2016 Elsevier Ltd


Hoye G.,Norwegian Defence Research Establishment FFI | Fridman A.,Norsk Elektro Optikk
Optics Express | Year: 2013

Current high-resolution push-broom hyperspectral cameras introduce keystone errors to the captured data. Efforts to correct these errors in hardware severely limit the optical design, in particular with respect to light throughput and spatial resolution, while at the same time the residual keystone often remains large. The mixel camera solves this problem by combining a hardware component - an array of light mixing chambers - with a mathematical method that restores the hyperspectral data to its keystone-free form, based on the data that was recorded onto the sensor with large keystone. A Virtual Camera software, that was developed specifically for this purpose, was used to compare the performance of the mixel camera to traditional cameras that correct keystone in hardware. The mixel camera can collect at least four times more light than most current high-resolution hyperspectral cameras, and simulations have shown that the mixel camera will be photon-noise limited - even in bright light - with a significantly improved signal-to-noise ratio compared to traditional cameras. A prototype has been built and is being tested. © 2013 Optical Society of America.


Hovland H.,Norwegian Defence Research Establishment FFI
Optics Express | Year: 2014

This work presents a novel imaging device based on tomographic reconstruction. Similar in certain aspects to the earlier presented tomographic scanning (TOSCA) principle, it provides several important enhancements. The device described generates a stream of onedimensional projections from a linear array of thin stripe detectors onto which the (circular) image of the scene is rotated. A two-dimensional image is then reproduced from the one-dimensional signals using tomographic processing techniques. A demonstrator is presented. Various aspects of the design and construction are discussed, and resulting images and movies are presented. ©2014 Optical Society of America


Skauli T.,Norwegian defence research establishment FFI
Optics Express | Year: 2011

Many types of hyperspectral image processing can benefit from knowledge of noise levels in the data, which can be derived from sensor physics. Surprisingly, such information is rarely provided or exploited. Usually, the image data are represented as radiance values, but this representation can lead to suboptimal results, for example in spectral difference metrics. Also, radiance data do not provide an appropriate baseline for calculation of image compression ratios. This paper defines two alternative representations of hyperspectral image data, aiming to make sensor noise accessible to image processing. A "corrected raw data" representation is proportional to the photoelectron count and can be processed like radiance data, while also offering simpler estimation of noise and somewhat more compact storage. A variance-stabilized representation is obtained by square-root transformation of the photodetector signal to make the noise signal-independent and constant across all bands while also reducing data volume by almost a factor 2. Then the data size is comparable to the fundamental information capacity of the sensor, giving a more appropriate measure of uncompressed data size. It is noted that the variance-stabilized representation has parallels in other fields of imaging. The alternative data representations provide an opportunity to reformulate hyperspectral processing algorithms to take actual sensor noise into account. © 2011 Optical Society of America.


Hanson T.,Norwegian Defence Research Establishment FFI
International Journal of Production Economics | Year: 2016

Most nations spend a considerable part of their gross domestic product (GDP) on defense. However, no previous study has addressed productivity and efficiency in the core area of the armed forces, operational units, using Data Envelopment Analysis (DEA). Introducing a model for the production process of an operational unit, productivity and efficiency are estimated by DEA for units of one branch of the Norwegian armed forces. Small samples are a characteristic of DEA studies in the military, and the public sector in general, resulting in nearly half of the units being estimated as fully efficient. We find that, by using the bootstrap technique to estimate confidence intervals, we can point to uncertainty in the estimates and reduce the number of candidates for best practice. © 2016 Elsevier B.V. All rights reserved. All rights reserved.


Hovland H.,Norwegian Defence Research Establishment FFI
Optics Express | Year: 2013

This work presents the first experimental demonstrator of an imager based on a tomographic scanning (TOSCA) principle. The device described generates a stream of multispectral images of a scene or target using simple conical scan optics and a simple patterned reticle, followed by collecting optics and one or several single pixel detectors. Tomographic processing techniques are then applied to the one-dimensional signals to reproduce two-dimensional images. Various aspects of the design and construction are described, and resulting images and movies are shown. © 2013 Optical Society of America.


Van Walree P.A.,Norwegian Defence Research Establishment FFI
IEEE Journal of Oceanic Engineering | Year: 2013

Systematic measurements were performed to characterize shallow-water acoustic propagation channels for applications in the field of underwater communications. The survey was conducted in northern Europe and covers the continental shelf, Norwegian fjords, a sheltered bay, a channel, and the Baltic Sea. The measurements were performed in various frequency bands between 2 and 32 kHz. The outcome of the study is a variety of channels that differ in many ways, defying any attempt to define a typical acoustic communication channel. Miscellaneous forward propagation effects are presented, which are relevant to channel models for the design of modulation schemes, network protocols, and simulation environments. © 2013 IEEE.


Hovland H.,Norwegian Defence Research Establishment FFI
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

The tomographic scanner (TOSCA) detects signals using line detectors scanning a scene at regularly distributed angles. These line scan signals are then processed to reconstruct 2-dimensional images. In the simplest form, a 1-axis rotating conical scan optics scans across a simple patterned reticle, the signal collection being done with a single pixel detector. Experimental mono- and multispectral cameras using this approach are demonstrated under varying illumination conditions. Of particular interest is the TOSCA system's ability to handle and compensate for light sources modulated with a frequency higher than that of the frame rate. We also demonstrate for the first time a TOSCA imager operating in the infrared region. The device is put together using 3D-printed key parts and low cost optical components, leading to a very economical infrared camera. © 2014 SPIE.


Skauli T.,Norwegian Defence Research Establishment FFI
Applied Optics | Year: 2013

The performance of spectral imagers is customarily described by several characteristics including resolution, noise, and coregistration. These must be traded off against each other in a practical imager design. This paper proposes a way to use the information capacity, in an information-theoretic sense, as a figure of merit for spectral imagers. In particular, it is shown how a metric [Opt. Express 20, 918 (2012)] can be used to incorporate coregistration performance in a definition of total noise, which in turn can be used in the definition of information capacity. As an example, it is shown how the information capacity can be used to optimize the pixel size in a simple case that can be treated analytically. Generally, the information capacity is attractive as a fundamental, application-independent figure of merit for spectral imager optimization and benchmarking. © 2013 Optical Society of America.

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