August 1998

Briefs : Photonics/Optics
Photochromic Image-Plane Filter Extends Dynamic Range of CCD

A simple technique for extending the dynamic range of a charge-coupled-device (CCD) video camera involves the use of photochromic material — the same material used in self-adjusting sunglasses. The dynamic range of an image is the ratio between the maximum and minimum brightness...

Briefs : Mechanical & Fluid Systems
Updated Program for Computing Stresses in Spur Gears

DANST-PC is version 3.01 of a computer program for analysis of the statics and dynamics of spur-gear systems. ["DANST" signifies "Dynamic Analysis of Spur Gear Transmissions." A previous version was described in "Computing Stresses in Spur Gears," NASA Tech Briefs, Vol. 19, No. 12 (December...

Briefs : Physical Sciences
Microwave-Heating Technique for Batch Processing

A microwave-heating technique provides for batch processing of multiple, identically sized and shaped samples of the same material. The technique involves (1) excitation of a symmetrical electromagnetic mode or modes in a symmetrical microwave cavity and (2) positioning the samples symmetrically...

Briefs : Electronics & Computers
"Smart" Optoelectronic Sensor System for Recognizing Targets

The Viewing Imager/Gimballed Instrumentation Laboratory and Analog Neural Three-Dimensional Processing Experiment (VIGILANTE) is a "smart" optoelectronic sensor system that features ultrafast processing of image information for recognition and tracking of targets. VIGILANTE serves as...

Briefs : Robotics, Automation & Control
Doped ZnTe: a Developmental Photorefractive Material

Zinc telluride is a semiconductive material that has been found to become photorefractive when it is suitably doped with vanadium or with manganese and vanadium. The combination of photorefractivity and semiconductivity make this material attractive for use in a variety of applications,...

Briefs : Photonics/Optics
A Polymeric Optical Correlator for Security Verification

Rapid technological progress, especially in computers, CCD technology, color printers and scanners makes forgery and counterfeit of identification documents such as credit cards, or other important objects, increasingly simple. Current techniques such as the embossed hologram on credit...

Briefs : Robotics, Automation & Control
Snakelike Robots Would Maneuver in Tight Spaces

Robots with multiple-link arms that could reach through narrow openings into hidden cavities are undergoing development. Called "multifunction dexterous boro-robots" (MDBRs), these robots would resemble snakes (see Figure 1), in both general appearance and in the slithering motion with which they...

Briefs : Robotics, Automation & Control
Wavy Blades for Secondary Centrifugal Blood-Pump Impeller

The rectangular-cross-section blades of a centrifugal secondary impeller in a ventricular-assist blood pump would be replaced with blades of wavy cross section, according to a proposal. As explained below, the resulting modification in the flow pattern would reduce the tendency toward...

Briefs : Electronics & Computers
Laser Doppler Velocimeter System for Use on Gas Turbines

A laser Doppler velocimeter (LDV) system has been developed for use on practical gas-turbine engines. The system has been used to measure inlet and exhaust velocities on an F-100 EMD engine from an F-15 airplane (see Figure 1). To perform this work successfully, it was necessary to...

Briefs : Photonics/Optics
Coherent Gradient Sensing for Measuring Curvature

Coherent gradient sensing (CGS) is a diffraction-based, noncontact optical technique for measuring the slight curvature of a nearly flat thin film or specimen surface. CGS is especially useful for measuring curvatures of micromechanical structures and of thin films in electronic devices, to...

Briefs : Electronics & Computers
Self-Checking Circuitry for Detecting Single-Event Latchups

High-performance electronic circuits would incorporate self-checking features for detection of radiation-induced single-event latchups (SELs), according to a proposal. The basic SEL-detection scheme calls for redundant circuitry and a current-voting scheme similar to voting schemes...

Briefs : Materials
LaNi₅₋ₓGeₓ Electrodes for Ni/MH Electrochemical Cells

Experiments have shown that improved hydride-forming negative electrodes for rechargeable nickel/metal hydride (Ni/MH) electrochemical cells can be made by substituting Ge for some of the Ni in LaNi5. A similar discovery regarding the substitution of Sn for some of the Ni...

Briefs : Photonics/Optics
Voltage-Tunable Surface-Plasmon Band-Pass Optical Filters

Voltage-tunable optical band-pass filters based on surface plasmon waves have been proposed. These filters would function at both visible and infrared wavelengths. Whereas liquid-crystal tunable optical filters now on the market exhibit efficiencies of 20 percent or less, theoretical...

Briefs : Photonics/Optics
Heteroepitaxy with Large Lattice Mismatch

A process for the growth of single-crystal (epitaxial) multilayer films has been developed at the Naval Surface Warfare Center, Dahlgren Division. This process is predicated on the preparation of a compliant interfacial "template" layer of atomic dimensions that can overcome large lattice mismatches....

Briefs : Physical Sciences
Miniature Microscope Without Lenses

In a proposed optical microscope, the focusing optics of a conventional microscope would be supplanted by a combination of a microchannel filter and an advanced electronic image sensor. Elimination of focusing optics would eliminate the need for the time-consuming focusing operation, making it possible to...

Briefs : Photonics/Optics
Methods of Manufacturing Fiber Optic Components

The methods described are used with existing fiber optic technologies, and are based on several patents and on disclosures now before the U.S. Patent and Trademark Office. The patents are No. 4,755,037 ("Fiber Optic Coupler," 1988); No. 4,765,816 ("Method and Apparatus for Making Optical Fiber...

Briefs : Physical Sciences
Microlenses for Calibrating Phase Doppler Particle Analyzers

Simple optical devices called "scattering reticles" have been invented for calibrating Phase Doppler Particle Analyzers (PDPAs), which are optical instruments that analyze scattered light to determine the sizes and velocities of droplets. A scattering reticle comprises a polymeric...

Briefs : Physical Sciences
Miniature Electron Microscopes Without Vacuum Pumps

The proposed electron microscope would function without the need for external vacuum pumps and thus have a significant reduction in size, mass, and power consumption, as compared to conventional (vacuum-pump-equipped) electron microscopes now used in many laboratories. These devices could be...

Briefs : Mechanical & Fluid Systems
Subliming Solid Microthrusters

Devices are proposed that would sublime solid propellants to generate small thrusts for maneuvering spacecraft with masses of no more than 15 kg. With solids rather than gases in propellant tanks, there would be no leakage and thus no waste of limited quantities of propellants. There would also be none of the...

Briefs : Materials
LaNi₅₋ₓSnₓ Electrodes for Ni/MH Electrochemical Cells

Experiments have shown that improved hydride-forming negative electrodes for rechargeable nickel/metal hydride (Ni/MH) electrochemical cells can be made by substituting Sn for some of the Ni in LaNi5. Since the year 1988, it has been known that partial substitution of Sn...

Briefs : Mechanical & Fluid Systems
Trefoil Rotary Flexure

The figure illustrates a device that flexes to allow rotation about a single axis through a total range of ±12°. This device was designed to offer the following advantages over commercial flexural pivots:

Briefs : Robotics, Automation & Control
Jewellike Bearings for Blood Pumps

Jewellike bearings have been devised to enhance the performance and safety of small rotary pumps that are used to increase or sustain flows of blood in cardiac patients. A pump of this type includes a spinning impeller in an axial- or radial-flow configuration. The impeller shaft is supported at its ends by...

Briefs : Photonics/Optics
Fiber Laser Amplifiers with Broad Applications

The Boeing Company has developed fiber-laser-amplifier technology representing the latest in diode-laser-pumped systems, providing high output power, high brightness, tunability, frequency-doubled output, multi-wavelength amplification, and narrow linewidth operation. The technology is a proven...

Briefs : Electronics & Computers
TRL Fixture for Cryogenic Testing of Microwave Components

A single-block fixture enables the rapid and accurate electrical characterization of planar microwave electronic components, by use of the through-reflect-line (TRL) technique, in air or in a vacuum at any temperature from ambient down to cryogenic temperatures. Heretofore, the TRL...

Briefs : Physical Sciences
Easy-to-Use High-Temperature Strain-Sensor Systems

Easy-to-use high-temperature strain-sensor systems based on strain gauges made from Pd/Cr-alloy wires have been developed. These systems include strain-gauge units comprising Pd/Cr wires bonded to high-temperature metal-alloy shims by flame spraying of ceramic materials. Optionally, a...

Briefs : Materials
Improved Bond-Coat Layers for Thermal-Barrier Coatings

Current production thermal-barrier coatings (TBCs) have been shown to be capable of reducing the average temperatures of metallic components by 50 to 80 °C and hot-spot temperature by up to 140 °C. This substantial temperature reduction has been used to extend the life of metallic...

Briefs : Electronics & Computers
Stable Breakdown Obtained in Silicon Carbide Rectifiers

Experiments have revealed that stable breakdown-voltage characteristics can be achieved in silicon carbide rectifiers. Stable breakdown-voltage characteristics are essential to the ability to withstand overvoltage transients and are therefore necessary for reliability in high-power...

Briefs : Photonics/Optics
Semimonolithic Cavities for Optical Frequency Conversion

Semimonolithic resonant structures external to lasers have been proposed for use in optical frequency-conversion applications - for example, doubling the frequencies of laser beams. These structures would offer most of the advantages, without most of the disadvantages, of monolithic...

Briefs : Materials
Trading Risk Versus Cost of a Composite-Material Structure

A probabilistic method has been developed for use in designing a composite-material structure to achieve a balance between maximum reliability and minimum cost. This method accounts for all naturally occurring uncertainties in properties of constituent materials, fabrication variables,...

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