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Sol-Gel Glass Holographic Light-Shaping Diffusers

Defined areas can be illuminated diffusely with high efficiency. Holographic glass light-shaping diffusers (GLSDs) are optical components for use in special-purpose illumination systems (see figure). When properly positioned with respect to lamps and areas to be illuminated, holographic GLSDs efficiently channel light from the lamps onto specified areas with specified distributions of illumination — for example, uniform or nearly uniform irradiance can be concentrated with intensity confined to a peak a few degrees wide about normal incidence, over a circular or elliptical area.

Posted in: Physical Sciences, Briefs

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Phase Correction for GPS Antenna With Nonunique Phase Center

Position can be determined more accurately. A method of determining the position and attitude of a body equipped with a Global Positioning System (GPS) receiver includes an accounting for the location of the nonunique phase center of a distributed or wraparound GPS antenna. The method applies, more specifically, to the case in which (1) the GPS receiver utilizes measurements of the phases of GPS carrier signals in its position and attitude computations and (2) the body is axisymmetric (e.g., spherical or round cylindrical) and wrapped at its equator with a single- or multiple-element antenna, the radiation pattern of which is also axisymmetric with the same axis of symmetry as that of the body.

Posted in: Physical Sciences, Briefs

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Estimating Aeroheating of a 3D Body Using a 2D Flow Solver

A method for rapidly estimating the aeroheating, shear stress, and other properties of hypersonic flow about a three-dimensional (3D) blunt body has been devised. First, the geometry of the body is specified in Cartesian coordinates. The surface of the body is then described by its derivatives, coordinates, and principal curvatures. Next, previously relatively simple equations are used to find, for each desired combination of angle of attack and meridional angle, a scaling factor and the shape of an equivalent axisymmetric body. These factors and equivalent shapes are entered as inputs into a previously developed computer program that solves the two-dimensional (2D) equations of flow in a non-equilibrium viscous shock layer (VSL) about an axisymmetric body. The coordinates in the output of the VSL code are transformed back to the Cartesian coordinates of the 3D body, so that computed flow quantities can be registered with locations in the 3D flow field of interest. In tests in which the 3D bodies were elliptic paraboloids, the estimates obtained by use of this method were found to agree well with solutions of 3D, finite-rate-chemistry, thin-VSL equations for a catalytic body.

Posted in: Physical Sciences, Briefs

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Miniature Focusing Time-of-Flight Mass Spectrometer

Resolution is retained despite the reduction in size. An improved miniature time-of-flight mass spectrometer has been developed in a continuing effort to minimize the sizes, weights, power demands, and costs of mass spectrometers for such diverse applications as measurement of concentrations of pollutants in the atmosphere, detecting poisonous gases in mines, and analyzing exhaust gases of automobiles.

Posted in: Physical Sciences, Briefs

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Measuring Humidity in Sealed Glass Encasements

This noninvasive technique helps in the preservation of valuable documents. A technique has been devised for measuring the relative humidity levels in the protective helium/water vapor atmosphere in which the Declaration of Independence, the United States Constitution, and the Bill of Rights are encased behind glass panels on display at the National Archives in Washington, DC. The technique is noninvasive: it does not involve penetrating the encasements (thereby risking contamination or damage to the priceless documents) to acquire samples of the atmosphere. The technique could also be applied to similar glass encasements used to protect and display important documents and other precious objects in museums.

Posted in: Physical Sciences, Briefs

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Science Instruments to Examine Pluto and Its Moon

Science instruments Southwest Research Institute San Antonio, TX 210-684-5111 www.swri.org

Posted in: Application Briefs

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Collaboration Software Connects NASA Employees with Suppliers

Teamcenter®product lifecycle management software UGS Corp. Plano, TX 341-264-8216 www.ugs.com

Posted in: Application Briefs

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