Tech Briefs

Photonics & Imaging

Access our comprehensive library of technical briefs on photonics and imaging, from engineering experts at NASA and major government, university, and commercial laboratories.

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Briefs: Photonics/Optics
Three modifications have been proposed for hydrogen sensors in which hydrogen in the air causes changes in the reflection spectra of interferometric film stacks that are interrogated via...
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Briefs: Photonics/Optics
A prototype wavelength-agile external-cavity diode laser (ECDL) was demonstrated in the first phase of a continuing effort to develop noninvasive laser-based instruments that would measure absolute...
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Briefs: Photonics/Optics
Enhanced Optical Microresonators for Detecting Molecules
Sensors based on microscopic optical resonators and arrays of such resonators have been proposed for detecting trace amounts of specific molecules in small gaseous, liquid, and solid samples. In addition to compactness, these sensors would offer ultrahigh sensitivity - in some cases, enough...
Briefs: Photonics/Optics
The figure depicts the optical layout and meridional-plane ray-trace diagram of a four-element superachromatic near-infrared (IR) lens system. The system features a 30-mm-diameter...
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Briefs: Photonics/Optics
Software for Multidisciplinary Concurrent Optical Design
The Integrated Optical Design Analyzer (IODA) is a computer program that facilitates multidisciplinary concurrent engineering of highly precise optical instruments. (IODA should not be confused with a multidisciplinary optical-system-analysis program, called "IMOS," that has been reported...
Briefs: Photonics/Optics
An optical assembly that combines the output of mutually incoherent lasers into a multibeam source for transmission into free space was designed, assembled, and tested. This design was motivated by the need for...
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Briefs: Photonics/Optics
Improved Fiber-Pigtailed Non-Planar Ring Oscillator Laser
An improved non-planar ring oscillator (NPRO) of the fiber-pigtailed type has been developed. The improvements over prior lasers of this type lie in details of design and construction that are intended to enhance mechanical stability and thereby increase the stability of optical...
Briefs: Photonics/Optics
Computing Atmospheric Profiles From Spectral Measurements
The SEASCRAPE computer program estimates the composition, temperature, and pressure of the atmosphere as a function of position by fitting remote-sounding spectroscopic data to a mathematical model of the transfer of radiation through the atmosphere. SEASCRAPE consists of two integrated...
Briefs: Photonics/Optics
Design and development of miniature paraboloidal mirrors that would be deflected magnetically to vary their radii of curvature (and thus their focal lengths)...
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Briefs: Photonics/Optics
Study of Stitching Errors in Shot-Shifted E-Beam Lithography
A report presents a study of the efficacy of shot shifting for reducing stitching errors in diffraction gratings made by electron-beam (E-beam) lithography. Stitching errors arise from fabricating a grating as a mosaic of smaller gratings by frequently translating the grating blank....
Briefs: Photonics/Optics
A prototype ring laser in which a transparent microsphere serves as an electromagnetic-mode selector has been constructed in a continuing effort to develop optoelectronic oscillators...
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Briefs: Physical Sciences
A class of proposed photonic switching devices would utilize interactions among light bullets that have been studied theoretically. Because they function at speeds much greater than those of...
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Briefs: Photonics/Optics
The figure depicts an example of a proposed type of optoelectronic oscillator (OEO) based on some of the same principles as those described in the preceding article. In the proposed...
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Briefs: Photonics/Optics
An assembly that includes electromechanical rotary actuators has been developed specifically for use as the shutter mechanism of a cryogenic infrared camera that will be part of an...
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Briefs: Photonics/Optics
Optoelectronic oscillators (OEOs) of a proposed type would be based partly on the use of fiber-optic linear or ring resonators in place of the long fiber-optic delay lines that have...
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Briefs: Photonics/Optics
Fractal-Based Encryption
In 1987 a discovery led to the formal proof that it is possible to use chaotic functions to arrive at a nonprobabilistic and nondeterministic method normal context of the operation of this system, and by using a virtual operational environment, the investigators are manipulating data in eight dimensions, which require a...
Briefs: Photonics/Optics
An apparatus that includes a pulsed electron gun and a high-resolution ultraviolet spectrometer has been developed for use in (1) pulsed electron-impact excitation of transitions among...
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Briefs: Photonics/Optics
Infrared-sensor systems for real-time detection of accretion of ice on helicopter rotor blades are undergoing development. By providing early warnings of icing conditions, these systems...
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Briefs: Photonics/Optics
Efforts are under way to develop back-surface-illuminated, thinned silicon charge-coupled devices (CCDs) with delta doping and integral optical filters to be used as image detectors...
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Briefs: Photonics/Optics
Capture and Escape of Charge Carriers in Quantum Dots
A report describes an experimental investigation of effects of thermally induced intermixing of In0.6Ga0.4As and GaAs on the dynamics of photoexcited charge carriers in In0.6Ga0.4As/GaAs quantum dots. The quantum dots (nanometer-size islands of In0.6Ga0.4As surrounded by GaAs) were grown by...
Briefs: Photonics/Optics
Rayleigh-Scattering Measurements in Underexpanded Jets
A report describes experiments in which time-averaged and unsteady local variations in the densities of underexpanded supersonic free jets issuing from a choked circular nozzle were measured by laser-induced Rayleigh scattering. This study is part of a continuing effort to understand the...
Briefs: Photonics/Optics
Common-path heterodyne interferometers (COPHIs) have been proposed for measuring small variations in the heights of surfaces. A COPHI could be used, for example, to measure the deviation of the surface of...
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Briefs: Physical Sciences
Shared-aperture multiplexed holographic scanning telescopes have been proposed for use in lidar transceivers and other laser transmitters and receivers in remote sensing instruments....
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Briefs: Physical Sciences
Experiments have demonstrated the feasibility of using flame-heated refractory dielectric solid bodies as wavelength-selective sources of light for special applications; in...
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Briefs: Electronics & Computers
Arrays of photon-counting detectors and associated digital signal processors have been proposed for receivers in optical communication systems in which the optical signals...
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Briefs: Photonics/Optics
Pyramid-Shape Light Coupler for Multi-Quantum-Well Photodetectors
Wavelength-independent light couplers in the form of planar arrays of pyramids have been proposed for use on multiple-quantum-well infrared photodetectors. Wavelength-independent light couplers are needed for focal-plane arrays of QWIPs designed to operate in multiple and/or broad...
Briefs: Photonics/Optics
A compact two-axis scanning-mirror assembly (see figure) has been developed for use as part of a laser rangefinder on a robotic vehicle. The assembly is designed to enable scanning of the laser beam...
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Briefs: Photonics/Optics
Quantum-well infrared photodetectors (QWIPs) that include two-dimensional surface grating light couplers would be modified, according to a proposal to incorporate crossed slots. It...
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Briefs: Physical Sciences
Two polarization-recycling techniques have been proposed to increase the efficiency of illumination of liquid-crystal display (LCD) panels. The motivation for this proposal lies in the...
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