Photonics/Optics

n-B-pi-p Superlattice Infrared Detector

A specially designed barrier (B) is inserted at the n-pi junction [where most G-R (generation-recombination) processes take place] in the standard n-pi-p structure to substantially reduce generation-recombination dark currents. The resulting n-B-pi-p structure also has reduced tunneling dark currents, thereby solving some of the limitations to which current type II strained layer superlattice infrared detectors are prone. This innovation is compatible with common read-out integrated circuits (ROICs).

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

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Monolithic, High-Speed Fiber-Optic Switching Array for Lidar

Electro-optic crystals allow for fast, multi-fiber switching without moving parts.Current fiber switch technologies use mechanical means to redirect light beams, resulting in slow switch time, as well as poor reliability due to moving parts wearing out quickly at high speeds. A non-mechanical ability to switch laser output into one of multiple fibers within a fiber array can provide significant power, weight, and costs savings to an all-fiber system.

Posted in: Briefs, TSP, ptb catchall, Tech Briefs, Mechanical Components, Photonics

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Radius of Curvature Measurement of Large Optics Using Interferometry and Laser Tracker

This method determines the curvature radius of large mirrors.The determination of radius of curvature (ROC) of optics typically uses either a phase measuring interferometer on an adjustable stage to determine the position of the ROC and the optics surface under test. Alternatively, a spherometer or a profilometer are used for this measurement.

Posted in: Briefs, TSP, ptb catchall, Tech Briefs, Photonics, Physical Sciences

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Creep Measurement Video Extensometer

This automated system measures test-sample creep rates for materials testing.Understanding material behavior under load is critical to the efficient and accurate design of advanced aircraft and spacecraft. Technologies such as the one disclosed here allow accurate creep measurements to be taken automatically, reducing error.

Posted in: Briefs, TSP, ptb catchall, Tech Briefs, Photonics, Physical Sciences

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General Tool for Evaluating High-Contrast Coronagraphic Telescope Performance Error Budgets

The Coronagraph Performance Error Budget (CPEB) tool automates many of the key steps required to evaluate the scattered starlight contrast in the dark hole of a space-based coronagraph. The tool uses a Code V prescription of the optical train, and uses MATLAB programs to call ray-trace code that generates linear beam-walk and aberration sensitivity matrices for motions of the optical elements and line-of-sight pointing, with and without controlled fine-steering mirrors (FSMs). The sensitivity matrices are imported by macros into Excel 2007, where the error budget is evaluated. The user specifies the particular optics of interest, and chooses the quality of each optic from a predefined set of PSDs. The spreadsheet creates a nominal set of thermal and jitter motions, and combines that with the sensitivity matrices to generate an error budget for the system.

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

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Microwave Tissue Soldering for Immediate Wound Closure

Wounds can be closed rapidly, without staples, sutures, or tapes.A novel approach for the immediate sealing of traumatic wounds is under development. A portable microwave generator and handheld antenna are used to seal wounds, binding the edges of the wound together using a biodegradable protein sealant or “solder.” This method could be used for repairing wounds in emergency settings, by restoring the wound surface to its original strength within minutes. This technique could also be utilized for surgical purposes involving solid visceral organs (i.e., liver, spleen, and kidney) that currently do not respond well to ordinary surgical procedures.

Posted in: Briefs, MDB, Briefs, Medical, Lasers & Laser Systems, Photonics

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Fiber Optic Technology: Shining New Light On An Old Concept

While it may appear state-of-the-art on the surface, fiber optic technology is a fairly simple method of conducting light that has been around for some time. The principle of guiding light by refraction was first demonstrated in the mid 19th century, and has been developing for use in practical applications ever since.

Posted in: Articles, Features, ptb catchall, Photonics

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