Special Coverage

Technique Provides Security for Multi-Robot Systems
Bringing New Vision to Laser Material Processing Systems
NASA Tests Lasers’ Ability to Transmit Data from Space
Converting from Hydraulic Cylinders to Electric Actuators
Automating Optimization and Design Tasks Across Disciplines
Vibration Tables Shake Up Aerospace and Car Testing
Supercomputer Cooling System Uses Refrigerant to Replace Water
Computer Chips Calculate and Store in an Integrated Unit
Electron-to-Photon Communication for Quantum Computing

Semiconductor Bolometers Give Background-Limited Performance

These devices can be fabricated inexpensively by use of established silicon-processing techniques.

Semiconductor bolometers that are capable of detecting electromagnetic radiation over most or all of the infrared spectrum and that give background-limited performance at operating temperatures from 20 to 300 K have been invented. The term “background-limited performance” as applied to a bolometer, thermopile, or other infrared detector signifies that the ability to detect infrared signals that originate outside the detector is limited primarily by thermal noise attributable to the background radiation generated external to the bolometer. The signal- to-noise ratios and detectivities of the bolometers and thermopiles available prior to this invention have been lower than those needed for background-limited performance by factors of about 100 and 10, respectively.

Posted in: Briefs, Semiconductors & ICs, Semiconductor devices, Sensors and actuators, Performance upgrades, Noise, Radiation

Multichannel X-Band Dielectric-Resonator Oscillator

Unlike other DROs, this one is electrically tunable.

A multichannel dielectric-resonator oscillator (DRO), built as a prototype of a local oscillator for an X-band transmitter or receiver, is capable of being electrically tuned among and within 26 adjacent frequency channels, each 1.16 MHz wide, in a band ranging from ≈7,040 to ≈7,070 GHz. The tunability of this oscillator is what sets it apart from other DROs, making it possible to use mass-produced oscillator units of identical design in diverse X-band applications in which there are requirements to use different fixed frequencies or to switch among frequency channels.

Posted in: Briefs, TSP, Semiconductors & ICs, Calibration, Architecture, Radio equipment, Product development

Control Software for Advanced Video Guidance Sensor

Embedded software has been developed specifically for controlling an Advanced Video Guidance Sensor (AVGS). [As described in several previous NASA Tech Briefs articles, a Video Guidance Sensor is an optoelectronic system that provides guidance for automated docking of two vehicles (space-craft in the original intended application). Such a system includes pulsed laser diodes and a video camera, the output of which is digitized. From the positions of digitized target images and known geometric relationships, the relative position and orientation of the vehicles are computed.] The present software consists of two subprograms running in two processors that are parts of the AVGS. The subprogram in the first processor receives commands from an external source, checks the commands for correctness, performs commanded non-image-data-processing control functions, and sends image-data-processing parts of commands to the second processor. The subprogram in the second processor processes image data as commanded. Upon power-up, the software performs basic tests of functionality, then effects a transition to a standby mode. When a command is received, the software goes into one of several operational modes (e.g. acquisition or tracking). The software then returns, to the external source, the data appropriate to the command.

Posted in: Briefs, TSP, Software, Architecture, Embedded software, Optics, Spacecraft guidance

Earth Observing System Data Gateway

The Earth Observing System Data Gateway (EDG) software provides a “onestop-shopping” standard interface for exploring and ordering Earth-science data stored at geographically distributed sites. EDG enables a user to do the following:
Posted in: Briefs, TSP, Software, Computer software and hardware, Human machine interface (HMI), Data management

Mercury Shopping Cart

Mercury Shopping Cart Interface (MSCI) is a reusable component of the Power User Interface 5.0 (PUI) program described in the immediately preceding article. MSCI is a means of encapsulating the logic and information needed to describe an orderable item consistent with Mercury Shopping Cart service protocol. Designed to be used with Web-browser software, MSCI generates Hypertext Markup Language (HTML) pages on which ordering information can be entered. MSCI comprises two types of Practical Extraction and Report Language (PERL) modules: template modules and shopping-cart logic modules. Template modules generate HTML pages for entering the required ordering details and enable submission of the order via a Hypertext Transfer Protocol (HTTP) post. Shopping-cart modules encapsulate the logic and data needed to describe an individual orderable item to the Mercury Shopping Cart service. These modules evaluate information entered by the user to determine whether it is sufficient for the Shopping Cart service to process the order. Once an order has been passed from MSCI to a deployed Mercury Shopping Cart server, there is no further interaction with the user.

Posted in: Briefs, TSP, Software, Communication protocols, Internet of things, Human machine interface (HMI), Data management

Cassini Archive Tracking System

The Cassini Archive Tracking System (CATS) is a computer program that enables tracking of scientific data transfers from originators to the Planetary Data System (PDS) archives. Without CATS, there is no systematic means of locating products in the archive process or ensuring their completeness. By keeping a database of transfer communications and status, CATS enables the Cassini Project and the PDS to efficiently and accurately report on archive status. More importantly, problem areas are easily identified through customized reports that can be generated on the fly from any Web-enabled computer. A Web-browser interface and clearly defined authorization scheme provide safe distributed access to the system, where users can perform functions such as create customized reports, record a transfer, and respond to a transfer. CATS ensures that Cassini provides complete science archives to the PDS on schedule and that those archives are available to the science community by the PDS. The three-tier architecture is loosely coupled and designed for simple adaptation to multi-mission use. Written in the Java programming language, it is portable and can be run on any Java-enabled Web server.

Posted in: Briefs, TSP, Software, Architecture, Data exchange, Internet, Documentation

Computing Fault Displacements From Surface Deformations

Simplex is a computer program that calculates locations and displacements of subterranean faults from data on Earth-surface deformations. The calculation involves inversion of a forward model (given a point source representing a fault, a forward model calculates the surface deformations) for displacements, and strains caused by a fault located in isotropic, elastic half-space. The inversion involves the use of nonlinear, multi-parameter estimation techniques. The input surface-deformation data can be in multiple formats, with absolute or differential positioning. The input data can be derived from multiple sources, including interferometric synthetic-aperture radar, the Global Positioning System, and strain meters. Parameters can be constrained or free. Estimates can be calculated for single or multiple faults. Estimates of parameters are accompanied by reports of their covariances and uncertainties. Simplex has been tested extensively against forward models and against other means of inverting geodetic data and seismic observations.

Posted in: Briefs, TSP, Software, Mathematical analysis, Computer software and hardware, Global positioning systems, Global positioning systems (GPS), Radar, Terrain

Thermal Light Valve Brings IR Imaging to the Masses

Technology uses MEMS structure with refractive properties sensitive to thermal radiation and reads out signal with inexpensive laser diode and CMOS sensor.

RedShift Systems, Waltham, Massachusetts

The desire to “see” in complete darkness or through obscurants such as smoke or fog has driven the development and adoption of thermal imaging technology. Thermal imaging is the translation of a scene’s heat signature — the 8-μm to 14-μm or long-wavelength infrared (LWIR) energy an object emits — into a visible image or data that can be interpreted by a computer.

Posted in: Briefs, ptb catchall, Tech Briefs, Photonics

Optically Driven Deformable Mirrors

There is no wiring on the back sides of these mirrors.

NASA’s Jet Propulsion Laboratory, Pasadena, California

Optically driven deformable mirrors may eventually supplant electrically driven deformable mirrors in some adaptive-optics and active-optics applications. Traditionally, the mirror facets in electrically driven deformable mirrors are actuated, variously, by means of piezoelectric, electrostrictive, microelectromechanical, liquid-crystal, or thermal devices. At least one such device must be dedicated to each facet, and there must be at least one wire carrying a control or drive signal to the device. If a deformable mirror comprises many (e.g., thousands) of facets, then wiring becomes a major problem for design, and the problem is compounded in cases of piezoelectric or other actuators for which high drive voltages are required. In contrast, in optically driven mirrors, the wiring problem is eliminated.

Posted in: Briefs, ptb catchall, Tech Briefs, Photonics, Mirrors, Wiring

Automatic Alignment of Displacement-Measuring Interferometer

Corrections are derived from fluctuations associated with circular dithering of a laser beam.

NASA’s Jet Propulsion Laboratory, Pasadena, California

A control system strives to maintain the correct alignment of a laser beam in an interferometer dedicated to measuring the displacement or distance between two fiducial corner-cube reflectors. The correct alignment of the laser beam is parallel to the line between the corner points of the corner-cube reflectors: Any deviation from parallelism changes the length of the optical path between the reflectors, thereby introducing a displacement or distance measurement error.

Posted in: Briefs, ptb catchall, Tech Briefs, Photonics, Measurements, Electronic control systems, Lasers, Test equipment and instrumentation

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