Special Coverage

Mechanoresponsive Healing Polymers
Variable Permeability Magnetometer Systems and Methods for Aerospace Applicationst
Evaluation Standard for Robotic Research
Small Robot Has Outstanding Vertical Agility
Smart Optical Material Characterization System and Method
Lightweight, Flexible Thermal Protection System for Fire Protection
High-Precision Electric Gate for Time-of-Flight Ion Mass Spectrometers
Polyimide Wire Insulation Repair System
Distributed Propulsion Concepts and Superparamagnetic Energy Harvesting Hummingbird Engine
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Photonic Choke-Joints for Dual-Polarization Waveguides

The joint is constructed from a conductive metal, and requires no maintenance or peripheral equipment to operate.Photonic choke-joint (PCJ) structures for dual-polarization waveguides have been investigated at NASA's Goddard Space Flight Center for use in device and component packaging. This interface enables the realization of a high-performance, non-contacting waveguide joint without degrading the in-band signal propagation properties. The choke properties of two tiling approaches — symmetric square Cartesian and octagonal quasi-crystal lattices of metallic posts — are explored and optimal PCJ design parameters are presented. For each of these schemes, the experimental results for structures with finite tilings demonstrate near ideal transmission and reflection performance over a full waveguide band.

Posted in: Briefs, Photonics

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Smart Optical Material Characterization System and Method

This technology creates a flexible, unified platform for dynamic smart optical material evaluation.NASA's Langley Research Center has developed an adaptable and powerful interferometric test platform that uniquely enables multi-parameter evaluation of a wide variety of smart optical materials (SOM). The patent-pending SOM characterization system was created to measure the dynamic optical response of stimuli-responsive (“smart”) optical materials while external physical/electrical/thermal/chemical/pressure/magneto stimuli are applied to the material. Using novel interferometric fringe analysis software and a multi-stimuli-capable SOM test cell, the SOM characterization system enables a wide variety of materials — such as liquid crystals, nonlinear crystals, electro- and thermo-active polymer optics, and magneto- or piezo-driven optics — to be optically characterized for real-time changes in intensity, phase, and polarization. The versatility of the SOM test platform combined with the powerful, efficient, and user-friendly software interface makes it a valuable tool for the research or commercial development of smart materials.

Posted in: Briefs, Photonics

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Compact Planar Microwave Blocking Filters

Innovators at NASA's Goddard Space Flight Center have designed, fabricated, and characterized absorptive thermal blocking filters for cryogenic microwave applications. The device allows direct integration of the high-frequency signal and microwave readout, and mitigates spurious resonances in the circuit response. This leads to improved electrical performance and a reduction in the required circuit area. The transmission line filter's input characteristic impedance is designed to match 50 ohms and its response has been validated from 0 to 50 GHz. The observed return loss in the 0 to 20 GHz design band is greater than 20 dB and shows graceful degradation with frequency. The filter's response is calculable, repeatable under cryogenic cycling, and is capable of providing an intrinsically broadband matched impedance termination.

Posted in: Briefs, Photonics

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System and Method for Generating a Frequency-Modulated Linear Laser Waveform

Applications include manufacturing equipment, robotics, surveillance and security, military imaging, and spectroscopy.NASA's Langley Research Center has made a breakthrough improvement in laser frequency modulation. Frequency modulation technology has been used for surface mapping and measurement in sonar, radar, and time-of-flight laser technologies for decades. Although adequate, the accuracy of distance measurements made by these technologies can be improved by using a high-frequency triangular-waveform laser instead of a sine waveform or lower-frequency radio or microwaves. This new system generates a triangular modulation waveform with improved linearity that makes possible precision laser radar (light detection and ranging [lidar]) for a variety of applications.

Posted in: Briefs, Photonics

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Systems and Methods for Mirror Mounting with Minimized Distortion

The use of larger, lighter, and more precise space optics requires not only a means of manufacture, but also a means of spacecraft integration and performance verification. Engineers at NASA's Goddard Space Flight Center (GSFC) have demonstrated a process capable of producing a high-precision, mounted, lightweight mirror, and have validated its on-orbit figure. This effort included the design of a mount capable of surviving the launch environment of a sounding rocket, as well as a mounting process that did not introduce performance-degrading figure distortion. Additionally, analysis techniques were developed and adapted to address the challenges in measuring an optic that exceeds its figure specification under the strain of its own weight.

Posted in: Briefs, Photonics

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Improved Approach to Exoplanet Coronagraphy

Visible nulling coronagraphy and interferometry requires that the wavefront errors be held to unprecedented precision in the presence of environmental disturbances. A Null Diversity algorithm is used to first attain the precision, but it does not execute at high enough temporal bandwidth to hold the precision for long periods of time (hours). The environmental changes, mostly vibration and jitter with some thermal drift, can be rapidly varying and thus require a fast control algorithm. To perform rapid control, an algorithm, based upon a series of approximations, has been developed and simulated at NASA Goddard Space Flight Center for the sensing and control, in closed loop, of extremely precise wave-front errors in an interferometer. It operates over the range of ~5 nanometers rms down to <100 picometers rms in closed loop at high bandwidth (~20 Hz) and is used to hold (i.e. maintain) the requisite wavefront error.

Posted in: Briefs, Photonics

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Apparatus and Method for a Light Direction Sensor

This invention, developed at NASA's Goddard Space Flight Center, was originally conceived as a high-accuracy, high-sensitivity, bi-axial Sun angle sensor, but has also been proposed for applications involving the general field of precisely measuring the direction in which light travels toward the sensor. It has applications in spacecraft navigation, formation flying in space, space beacons, and automotive collision avoidance.

Posted in: Briefs, Photonics

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