Physical Sciences

Diode-Laser-Based Spectrometer for Sensing Gases

A diode-laser-based spectrometer has been developed for measuring concentrations of gases and is intended particularly for use in analyzing and monitoring combustion processes under microgravitational conditions in a drop tower or a spacecraft.

Posted in: Physical Sciences, Briefs, TSP

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Scattering-Type Surface-Plasmon-Resonance Biosensors

Sensitivities would greatly exceed those of reflection-type SPR biosensors. Biosensors of a proposed type would exploit scattering of light by surface plasmon resonance (SPR). Related prior biosensors exploit absorption of light by SPR. Relative to the prior SPR biosensors, the proposed SPR biosensors would offer greater sensitivity — in some cases, enough sensitivity to detect bioparticles having dimensions as small as nanometers.

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Microparticle Flow Sensor

As many as 1,000 microparticles can be identified, tracked, and counted. The microparticle flow sensor (MFS) is a system for identifying and counting microscopic particles entrained in a flowing liquid. The MFS includes a transparent, optoelectronically instrumented laminar-flow chamber (see figure) and a computer for processing instrument-readout data. The MFS could be used to count microparticles (including micro-organisms) in diverse applications — for example, production of microcapsules, treatment of wastewater, pumping of industrial chemicals, and identification of ownership of liquid products.

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Pd/CeO2/SiC Chemical Sensors

Nanostructured interfacial CeO2 layers contribute to thermal stability and transfer of electrons. The incorporation of nanostructured interfacial layers of CeO2 has been proposed to enhance the performances of Pd/SiC Schottky diodes used to sense hydrogen and hydrocarbons at high temperatures. If successful, this development could prove beneficial in numerous applications in which there are requirements to sense hydrogen and hydrocarbons at high temperatures: examples include monitoring of exhaust gases from engines and detecting fires.

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Fiber-Optic Sensor Would Monitor Growth of Polymer Film

Changes in thickness would be inferred from interference fringes. A proposed optoelectronic sensor system would measure the increase in thickness of a film of parylene (a thermoplastic polymer made from para-xylene) during growth of the film in a vapor deposition process. By enabling real-time monitoring of film thickness, the system would make it possible to identify process conditions favorable for growth and to tailor the final thickness of the film with greater precision than is now possible.

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Theodolite Ring Lights

These lights facilitate the use of spherical tooling balls as position references. Theodolite ring lights have been invented to ease a difficulty encountered in the well-established opticalmetrology practice of using highly reflective spherical tooling balls as position references. As described in more detail below, a theodolite ring light is attached to a theodolite or telescope and used to generate a visible target on a tooling ball.

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White-Light Whispering-Gallery-Mode Optical Resonators

Overlapping resonator modes are exploited to obtain wide, high-Q spectra. Whispering-gallery-mode (WGM) optical resonators can be designed to exhibit continuous spectra over wide wavelength bands (in effect, white-light spectra), with ultrahigh values of the resonance quality factor (Q) that are nearly independent offrequency. White-light WGM resonators have potential as superior alternatives to(1) larger, conventional optical resonators in ring-down spectroscopy, and (2) optical-resonator/electro-opticalmodulator structures used in coupling of microwave and optical signals in atomic clocks. In these and other potential applications, the use of white-light WGM resonators makes it possible to relax the requirement of high-frequency stability of lasers, thereby enabling the use of cheaper lasers.

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