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We report on the performance of planar silicon diodes operating in the double injection mode and emitting modulated infrared radiation at temperature range above 300 K. Results present theoretical analysis and experimental verification of an optimization aimed at maximal difference between emissivity of this structure for cases with and without forward bias applied to p–n junction. Several advantages of the structures were shown: wide emission spectrum (3÷12m), short rise-fall time (300s), high operating temperature (≈400 K). These planar photonic sources can be used as easily controlled sources of modulated infrared radiation in wide spectral range, image simulators, e.g. dynamic scene simulation devices with frame frequencies well above 200 Hz and for measurements of thermovision camera dynamic parameters. © 2010 Elsevier B.V. All rights reserved.

Development of highly efficient security systems is one of the most urgent topics for science and engineering. There are many kinds of threats and many methods of prevention. It is very important to detect a threat as early as possible in order to neutralize it. One of the very challenging problems is detection of dangerous objects hidden under human's clothing. This problem is particularly important for safety of airport passengers. In order to develop methods and algorithms to detect hidden objects it is necessary to determine the thermal signatures of such objects of interest. The laboratory measurements were conducted to determine the thermal signatures of dangerous tools hidden under various clothes in different ambient conditions. Cameras used for measurements were working in spectral range 0.6-12.5 μm An infrared imaging Fourier transform spectroradiometer was also used, working in spectral range 7.7-11.7 μm. Analysis of registered thermograms and hyperspectral datacubes has yielded the thermal signatures for two types of guns, two types of knives and home-made explosive bombs. The determined thermal signatures will be used in the development of method and algorithms of image analysis implemented in proposed monitoring systems.

The article presents the detection of gases using an infrared imaging Fouriertransform spectrometer (IFTS). The Telops Company has developed the IFTS instrument HyperCam, which is offered as short or long wave infrared device. The principle of HyperCam operation and methodology of gases detection has been shown in the paper, as well as theoretical evaluation of gases detection possibility. The calculation of an optical path between an IFTS device, cloud of gases and background has been also discussed. The variation of a signal reaching the IFTS caused by the presence of a gas has been calculated and compared with the reference signal obtained without the presence of a gas in IFTS’s field of view. Verification of theoretical result has been made by laboratory measurements. Some results of the detection of various types of gases have also been included in the paper.

In this paper we discuss a choice between the diffractive and refractive binary micro-lenses for the longwave IR FPA. To investigate diffraction on the micro-lenses we have used a numerical code based-on the rigorous electromagnetic theory, because neither geometrical optics nor thin element approach of scalar diffraction theory can correctly describe waveguide, shadowing and interference effects inside the micro-lens surface relief. These effects strongly influence the micro-lens diffraction efficiency when the width of the surface-relief features is close to the wavelength.

This paper presents emisivity (e) measurements for some materials used in microelectronics, eg.: aluminium, silicon, germanium and diamond-like structures. In this work we emphasise emissivity evaluation for semitransparent and multilayer dielectric materials. The measurement was performed with the use of IR Spectrometer. For every sample we measured the reflected and transmitted energy, and evaluated material constants for various spectral ranges. The results of this work may be useful in calculating heat removal by radiation in microelectronic devices.

The zero-bias resistance-area product ( R o A ) of LN 2 temperature Cd x Hg 1− x Te 8–14 μm range photodiodes has been calculated. The influence of the types: the Auger and the radiative recombination in p - and n -type regions was taken into account. It was shown that the photodiode ultimate performance is determined by the Auger 7 recombination in p -type material. The ultimate value of ( R o A ) is about 8 Ω cm 2 and it is much lower than calculated in recent works.

Experimental work directed toward the development of means for in-process control of residual stress during tube drawing is described. Experiments were done on 304 and 321 stainless steels, Incoloy 800, and copper tubing. While classical tube reducing processes, such as mandrel and plug drawing and sinking were the main objective, limited data on the effects of reeling and rock-rolling were also included. The distribution of residual axial and hoop stresses across the wall was determined by a Sachs’ analysis. Tandem drawing, wherein a small reduction (∼2 percent) was taken in the second die, produced a drastic reduction of the residual stress levels. A tapered bearing exit-die was specially efficient in this respect. However, the method was inefficient in pure sinking which always left residual stresses of high magnitude.

Design prerequisites were examined for a strip mill which would spontaneously provide a nearly-uniform percent reduction of thickness across a metal sheet or strip regardless of the latter’s cross-sectional form. The main requirement is that the flexural rigidity of the roll assembly be small (yet finite) and that the rolls be loaded uniformly over their working length rather than be end-supported. When operated with front and back tensions, a machine built along these lines should also correct initially malshaped material. The analysis is supported by a computer-solved comprehensive example wherein a conventional 4-high and a “flexible,” hydraulically loaded cluster mill are compared.

The principal parameters involved in drawing of metal tubes containing metallic, mineral, and organic powders were investigated on small copper, mild steel, and 304 stainless tubing. The type of filler controlled the change of the ratio of diameter to wall thickness which decreased at first but became constant after a certain reduction. The above decrease could be held to a minimum by employing a center rod of ductile metal separated from the tube by a powder barrier. The particulate core or barrier need not form an integral part of the product but can be used as a “deformable mandrel” being eventually removed from the reduced tube by reeling, melting, dissolving, or washing the powder out. Such a drawing procedure should prove useful in bulk reducing hard to draw (e.g., refractory) tubing. If warm drawing is called for, the operation is facilitated by the substantial heat capacity of the quasi-solid cross section. The danger of local interwelding (galling) between tube and inside tool is eliminated because of the absence of relative slippage between tube and inside tool.

La temperature de reponse «morte» (temperature d'une source de rayonnement de corps noir pour laquelle la reponse en tension totale du detecteur photoelectromagnetique est nulle) peut etre un parametre utile pour caracteriser les performances des detecteurs IR photoelectromagnetiques a couches minces

WILSON1 has recently reported that the intensity of magnetization of a high-carbon steel increases with plastic deformation of one kind, but that it suffers a recession after a relatively small additional plastic strain applied in a direction opposite to that originally used. I suggest that these results could be predicted from an analysis of the Bauschinger effect.

IT is well known that ductile metals in the soft condition work-harden progressively when subject to cyclic straining, for example, in fatigue testing. On the other hand, I have shown1 that metals originally cold-worked soften when plastically deformed under conditions in which a Bauschinger effect is operative. Since a Bauschinger effect is to be expected whenever the original and superimposed methods of deformation differ, it can be anticipated that initially cold-reduced metals may soften when later exposed to cyclic plastic strains. This is confirmed by the following experiments (see graph).