Photonics

Going Green in the Workplace with LEDs

In August 2007, Cree’s management made a bold decision to replace the existing fluorescent lighting technology at its Durham, NC facility with new energy-saving, environmentally friendly LED lighting technology. The group started with the company’s headquarters building, but eventually plans to replace more than 7,000 existing fluorescent light fixtures covering more than 800,000 square feet campus-wide. Phase one replaced 200 existing fixtures in 7,000 square feet of space in the visitor lobby, waiting areas and conference rooms. All the exterior parking lot lighting was also converted from high-pressure sodium to LED lighting. Both parts of phase one had to be completed by early November 2007, just 3 months later.

Posted in: Features, ptb catchall, Photonics, Articles

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Precision Prism Manufacturing — Art or Science?

Prisms are used in countless optical systems — from the pair of binoculars in your closet to cutting edge targeting systems to retroreflectors on the Moon. In modern, high-end optical systems, precision optics may be required that push the envelope of manufacturability within given cost constraints. Prisms are an integral component in many of these systems and often require manual fabrication in small quantities; however, they save space, mounting time, and materials, presenting opportunities as well as challenges for optical system designers.

Posted in: ptb catchall, Applications, Photonics, Application Briefs

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Multichannel Monitor-Stabilizer for Injection-Locked Lasers

NASA’s Jet Propulsion Laboratory, Pasadena, California Temp Tracker and Temp Tracker 12 ch (single-channel and 12-channel versions) programs are designed for use with an atomic gravity gradiometer. They support the stable operation of the injection-locked slave laser(s) in an autonomous regime. Due to changes of environmental conditions and aging, slave lasers tend to drift from the locking range and need to be relocked. This program checks the injection-locking range for each slave laser and re-centers them with respect to the master lasers, if needed. The master laser is assumed to be locked at an absorption line of Cs.

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

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Self-Quenching Single-Photon Detector

The detector has applications in nuclear physics instruments, spectroscopy, night-vision devices, and biological instrumentation. NASA’s Jet Propulsion Laboratory, Pasadena, California The self-quenching single-photon detector exhibits unique avalanching behaviors. It can automatically quench each of the Geiger mode avalanche events occurring inside the detector, can maintain the capability over a broad bias range, and can output explicit pulses with virtually constant and high value gain.

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

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Reducing Temperature Effects in Optical Resonator Sensors

Influences of temperature fluctuations are suppressed by factors of about 105. NASA’s Jet Propulsion Laboratory, Pasadena, California A differential-frequency measurement technique has been devised to reduce the spurious contributions of temperature fluctuations to determinations of physical quantities from readings of optical resonator and interferometric sensors. The technique is applicable mainly to sensors in the form of whispering-gallery mode (WGM) optical resonators. The evanescent electromagnetic fields of such resonators interact with their environments, such that their resonance frequencies change in response to environmental changes (e.g., a change in the index of refraction of the surrounding medium) that one seeks to measure. The resonance frequencies also vary significantly with temperature, with consequent introduction of errors and uncertainties and, hence, effective loss of sensitivity to changes in quantities other than temperature that one seeks to determine.

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

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Using Laser Vibrometry to Validate Gossamer Space Structures

NASA has been developing large ultra-lightweight structures commonly referred to as Gossamer space structures for many years to reduce launch costs and to exploit the unique capabilities of particular concepts. For instance, dish antennas are currently being pursued because they can be inflated in space to sizes as large as 30 meters and then rigidized to enable high data rate communications.

Posted in: Features, ptb catchall, Photonics, Articles

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Nanophotonics Principles and Applications

The term “nanophotonics” is used to encompass the scientific study of the interaction of matter and light at the nanometer scale. It is possible to design nanometer scale devices to slow down, enhance, produce, or manipulate light by understanding how light behaves as it travels through, or otherwise interacts with, materials at the nanometer scale. Two applications where nanophotonics have had an impact on society are devices used in optical switching for telecommunications and Organic Light Emitting Diodes (OLEDs) used in display technology and lighting.

Posted in: ptb catchall, Applications, Photonics, Application Briefs

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