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
Home

Statistical Sampling of Tide Heights Study

The goal of the study was to determine if it was possible to reduce the cost of verifying computational models of tidal waves and currents. Statistical techniques were used to determine the least number of samples required, in a given situation, to remain statistically significant, and thereby reduce overall project costs. Commercial, academic, and Federal agencies could benefit by applying these techniques, without the need to “touch” every item in the population. For example, the requirement of this project was to measure the heights and times of high and low tides at 8,000 locations for verification of computational models of tidal waves and currents. The application of the statistical techniques began with observations to determine the correctness of submitted measurement data, followed by some assumptions based on the observations.

Posted in: Briefs, Materials

Read More >>

Wafer-Level Lens Alignment

Over one billion cell phones with cameras are sold every year, and this number has been increasing annually at a rate of about 15 percent for the past 7 years. Approximately 80 percent of cell phones now have embedded cameras, with about 20 percent of new cell phones having two cameras – one on the back for taking photographs and one on the front for videoconferencing.

Posted in: Application Briefs, ptb catchall

Read More >>

Multiparallel Three-Dimensional Optical Microscopy

Lyndon B. Johnson Space Center, Houston, Texas Multiparallel three-dimensional optical microscopy is a method of forming an approximate three-dimensional image of a microscope sample as a collection of images from different depths through the sample. The imaging apparatus includes a single microscope plus an assembly of beam splitters and mirrors that divide the output of the microscope into multiple channels. An imaging array of photodetectors in each channel is located at a different distance along the optical path from the microscope, corresponding to a focal plane at a different depth within the sample. The optical path leading to each photodetector array also includes lenses to compensate for the variation of magnification with distance so that the images ultimately formed on all the photodetector arrays are of the same magnification.

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

Read More >>

Sub-Aperture Interferometers

Multiple target sub-beams are derived from the same measurement beam. NASA’s Jet Propulsion Laboratory, Pasadena, California Sub-aperture interferometers — also called wavefront-split interferometers — have been developed for simultaneously measuring displacements of multiple targets. The terms “sub-aperture” and “wavefront-split” signify that the original measurement light beam in an interferometer is split into multiple sub-beams derived from non-overlapping portions of the original measurement- beam aperture. Each measurement sub-beam is aimed at a retroreflector mounted on one of the targets. The splitting of the measurement beam is accomplished by use of truncated mirrors and masks, as shown in the example below.

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

Read More >>

Vacuum-Compatible Wideband White Light and Laser Combiner Source System

NASA’s Jet Propulsion Laboratory, Pasadena, California For the Space Interferometry Mission (SIM) Spectrum Calibration Development Unit (SCDU) testbed, wideband white light is used to simulate starlight. The white light source mount requires extremely stable pointing accuracy (hts were coupled to a photonic crystal fiber (PCF).

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

Read More >>

Stabilization of Phase of a Sinusoidal Signal Transmitted Over Optical Fiber

Two-way transmissions allow for rapid correction of common reference tones. NASA’s Jet Propulsion Laboratory, Pasadena, California In the process of connecting widely distributed antennas into a coherent array, it is necessary to synchronize the timing of signals at the various locations. This can be accomplished by distributing a common reference signal from a central source, usually over optical fiber. A high-frequency (RF or microwave) tone is a good choice for the reference. One difficulty is that the effective length of the optical fiber changes with temperature and mechanical stress, leading to phase instability in the received tone. This innovation provides a new way to stabilize the phase of the received tone, in spite of variations in the electrical length of the fiber.

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

Read More >>

Optical Tapers as White-Light WGM Resonators

Such resonators could be attractive for broad-band optical processing applications. NASA’s Jet Propulsion Laboratory, Pasadena, California A theoretical analysis has revealed that tapered optical waveguides could be useful as white-light whispering-gallery-mode (WGM) optical resonators. The compactness and the fixed-narrow-frequency-band nature of the resonances of prior microdisk and microsphere WGM resonators are advantageous in low-power, fixed-narrow-frequency-band applications. However for optical-processing applications in which there are requirements for power levels higher and/or spectral responses broader than those of prior microdisk and microsphere WGM resonators, white-light WGM resonators in the form of optical tapers would be preferable.

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

Read More >>

The U.S. Government does not endorse any commercial product, process, or activity identified on this web site.