Tech Briefs

Improved Charge-Transfer Fluorescent Dyes

Improved charge- transfer fluorescent dyes have been developed for use as molecular probes. These dyes are based on benzofuran nuclei with attached phenyl groups substituted with, variously, electron donors, electron acceptors, or combi- nations of donors and acceptors. Optionally, these dyes could be incorporated as parts of polymer backbones or as pendant groups or attached to certain surfaces via self-assembly-based methods.

Posted in: Briefs, Materials


Measuring Two Key Parameters of H3 Color Centers in Diamond

These parameters are needed for the further development of diamond lasers.A method of measuring two key parameters of H3 color centers in diamond has been created as part of a continuing effort to develop tunable, continuouswave, visible lasers that would utilize diamond as the lasing medium. (An H3 color center in a diamond crystal lattice comprises two nitrogen atoms substituted for two carbon atoms bonded to a third carbon atom. H3 color centers can be induced artificially; they also occur naturally. If present in sufficient density, they impart a yellow hue.) The method may also be applicable to the corresponding parameters of other candidate lasing media. One of the parameters is the number density of color centers, which is needed for designing an efficient laser. The other parameter is an optical-absorption cross section, which, as explained below, is needed for determining the number density.

Posted in: Briefs, TSP, Physical Sciences


Networked Equipment Makes Spherical and Aspheric Optics Manufacturing Predictable

Optical component production becomes more stable and predictable when metrology results inform the manufacturing process. In their quest for the twin grails of high production volume and extreme precision in the manufacture of both spherical and aspherical optical surfaces, manufacturers have been stymied by the difficulty of translating measurement results obtained from metrology tools to adjustments of grinding and polishing processes. In the past, this process involved manual analysis by highly skilled technical personnel — in other words, error-prone humans.

Posted in: Briefs, Physical Sciences


Video-Camera-Based Position- Measuring System

Coordinates of nearby targeted objects are measured quickly, easily, and safely. A prototype optoelectronic system measures the three dimensional relative coordinates of objects of interest or of targets affixed to objects of interest in a workspace. The system includes a charge-coupled-device video camera mounted in a known position and orientation in the workspace, a frame grabber, and a personal computer running image-data-processing software. Relative to conventional optical surveying equipment, this system can be built and operated at much lower cost; however, it is less accurate. It is also much easier to operate than are conventional instrumentation systems. In addition, there is no need to establish a coordinate system through cooperative action by a team of surveyors.

Posted in: Briefs, Electronics & Computers


Insect-Inspired Optical-Flow Navigation Sensors

Optical mouse chips are used to measure optical flow. Integrated circuits that exploit optical flow to sense motions of computer mice on or near surfaces (“optical mouse chips”) are used as navigation sensors in a class of small flying robots now undergoing development for potential use in such applications as exploration, search, and surveillance. The basic principles of these robots were described briefly in “Insect-Inspired Flight Control for Small Flying Robots” (NPO-30545), NASA Tech Briefs, Vol. 29, No. 1 (January 2005), page 61. To recapitulate from the cited prior article: The concept of optical flow can be defined, loosely, as the use of texture in images as a source of motion cues. The flight-control and navigation systems of these robots are inspired largely by the designs and functions of the vision systems and brains of insects, which have been demonstrated to utilize optical flow (as detected by their eyes and brains) resulting from their own motions in the environment.

Posted in: Briefs, TSP, Electronics & Computers


Faster Evolution of More Multifunctional Logic Circuits

Evolution is driven to find circuits that perform larger numbers of logic functions. A modification in a method of automated evolutionary synthesis of voltage controlled multifunctional logic circuits makes it possible to synthesize more circuits in less time. Prior to the modification, the computations for synthesizing a four-function logic circuit by this method took about 10 hours. Using the method as modified, it is possible to synthesize a six function circuit in less than half an hour.

Posted in: Briefs, TSP, Semiconductors & ICs


N-Type d Doping of High-Purity Silicon Imaging Arrays

Success depends on details of a low-temperature MBE process. A process for n-type (electron-donor) delta (d) doping has shown promise as a means of modifying back-illuminated image detectors made from n-doped high-purity silicon to enable them to detect high-energy photons (ultraviolet and x-rays) and low-energy charged particles (electrons and ions). This process is applicable to imaging detectors of several types, including charge-coupled devices, hybrid devices, and complementary metal oxide/semiconductor detector arrays.

Posted in: Briefs, TSP, Semiconductors & ICs


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