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2684 results about "Emissivity" patented technology

The emissivity of the surface of a material is its effectiveness in emitting energy as thermal radiation. Thermal radiation is electromagnetic radiation and it may include both visible radiation (light) and infrared radiation, which is not visible to human eyes. The thermal radiation from very hot objects (see photograph) is easily visible to the eye. Quantitatively, emissivity is the ratio of the thermal radiation from a surface to the radiation from an ideal black surface at the same temperature as given by the Stefan–Boltzmann law. The ratio varies from 0 to 1. The surface of a perfect black body (with an emissivity of 1) emits thermal radiation at the rate of approximately 448 watts per square metre at room temperature (25 °C, 298.15 K); all real objects have emissivities less than 1.0, and emit radiation at correspondingly lower rates.

Non-contacting temperature sensing device

The device according to the invention provides a non-contacting temperature sensing device incorporating micro-bolometric detectors as the suitable infrared sensors for automotive applications. A first and second infrared sensors each include an active infrared sensing element and a temperature drift compensating element. A current bias is applied to the active infrared sensing element as well as to the temperature drift compensating element, which is identical in structure with the active infrared sensing element, and the voltage outputs of these two elements pass through a differential amplifier. The fluctuation in the substrate temperature or the ambient temperature affects the active sensing element and the compensating element in the same way, thus it is cancelled out. Instead of using one spectral band of the infrared radiation, as in the prior art, two spectral bands are used resulting in a first and second signal generated by the first and second infrared sensors. A ratio of the first and second signals is obtained. The ratio of the signals is emissivity independent, so that the device of the present invention provides a more accurate measurement of temperature. The need to compensate for window contamination is also eliminated by this two band approach. The filtering elements for the two bands can be multi-layer thin film filters either coated on flat windows or on diffractive micro-lenses. The use of diffractive micro-lenses further reduces the size of the device, and eliminates the need for a separate optical lens.
Owner:MONTEREY RES LLC +1

Method and apparatus for alignment, comparison and identification of characteristic tool marks, including ballistic signatures

Systematic use of infrared imaging characterizes marks made on items and identifies the particular marking tool with better accuracy than use of visual imaging. Infrared imaging performed in total darkness eliminates shadows, glint, and other lighting variations and artifacts associated with visible imaging. Although normally used to obtain temperature measurements, details in IR imagery result from emissivity variations as well as thermal variations. Disturbing an item's surface texture creates an emissivity difference producing local changes in the infrared image. Identification is most accurate when IR images of unknown marks are compared to IR images of marks made by known tools. However, infrared analysis offers improvements even when only visual reference images are available. Comparing simultaneous infrared and visual images of an unknown item, such as bullet or shell casing, can detect illumination-induced artifacts in the visual image prior to searching the visual database, thereby reducing potential erroneous matches. Computer numerically controlled positioning of the toolmark relative to imaging sensors which use fixed focus optics with shallow depth of focus, varying focus distance and orientation systematically to construct a sequence of images, maximizes reliability of resulting images and their comparisons.
Owner:PROKOSKI FRANCINE J

Solar selective coating having higher thermal stability useful for harnessing solar energy and a process for the preparation thereof

The present invention provides an improved solar selective multilayer coating having higher thermal stability and a process for the preparation thereof. Solar selective coatings having higher thermal stability are useful in solar steam generation, solar steam turbines to produce electricity and also on automobile engine components. In the present invention, a tandem stack of three layers of TiAlN, TiAlON and Si3N4 is deposited on metal and non-metal substrates at room temperature using a planar reactive direct current magnetron sputtering process. The first two layers function as the absorber and the third antireflection layer further enhances the coating's absorptance. The solar selective coatings were annealed in air and vacuum to test the thermal stability at different temperatures and durations. The coatings of the present invention deposited on copper substrates are stable in air up to a temperature of 625° C. for a duration of 2 hours and exhibit higher solar selectivity in the order of 9-10 and these coating also show no change in the absorptance and the emittance values even after vacuum annealing at 600° C. for 3 hours. Coatings deposited on copper substrates showed no significant degradation in the optical properties even after continuous heating in air at 525° C. for 50 hours. The solar selective coatings of the present invention exhibit high hardness, high oxidation resistance, chemical inertness and stable microstructure.
Owner:COUNCIL OF SCI & IND RES
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