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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 253 records · Page 14

On-Board Calibrator for the Multi-angle Imaging SpectroRadiometer

The EOS/MISR instrument includes nine pushroom cameras, each at different view to Earth, and an on-board calibrator. The latter includes photodiode detectors, used as the radiometric standards for the experiment, and two Spectralon diffuse panels.

Multi-angle Imaging SpectroRadiometer pushroom cam↗

Negative Avalanche Feedback Detectors for Photon-Counting Optical Communications

Negative Avalanche Feedback photon counting detectors with near-infrared spectral sensitivity offer an alternative to conventional Geiger mode avalanche photodiode or phototube detectors for free space communications links at 1 and 1.55 microns. These devices demonstrate linear mode photon counting without requiring any external reset circuitry and may even be operated at room temperature. We have now characterized the detection efficiency, dark count rate, after-pulsing, and single photon jitter for three variants of this new detector class, as well as operated these uniquely simple to use devices in actual photon starved free space optical communications links.

single photon detector↗

Simple circuit positions film frames in projector

Individual frames on a photographic film strip in a projector are automatically positioned by a simple circuit. The circuit uses a photodiode that senses frame registry position and a relay that stops the film-advance motor to suspend the film at point of registry.

Silver, R. H.↗

A new solid-state logarithmic radiometer

Combination of temperature-compensated logarithmic amplifiers and p-i-n photodiodes operating in zero-bias mode provides lightweight radiometer for detecting spectral intensities encompassing more than three decades over a range of at least 300 to 800 nanometers at low power levels.

Burrous, C. N.↗

Particle detection by a light-scattering technique

Instrument measures concentration of small particles in aqueous medium in terms of amount of light scattered and degree to which light transmission is attenuated. Sensitivity to small particles is optimized because both scattered and transmitted illumination levels are detected by photodiodes.

Kormanyos, S.↗

Temperature compensation of light-emitting diodes

Circuit which includes a thermistor-resistor combination to compensate for temperature fluctuations by supplying input voltage to light-emitting diode, maintains constant light output. Similar circuits can be used for temperature-induced variations in photodiode applications.

Deboo, G. J.↗

An absentee monitoring device

Development of audio alarm system to provide remote monitoring of warning devices is discussed. Device uses photodiode connected to self-powered audio alarm unit. Photograph of equipment is included.

Meadows, A. L.↗

Binary-selectable detector holdoff circuit

High-speed switching circuit protects detectors from sudden, extremely-intense backscattered radiation that results from short-range atmospheric dust layers, or low-level clouds, entering laser/radar field of view. Function of circuit is to provide computer-controlled switching of photodiode detector, preamplifier power-supply voltages, in approximately 10 nanoseconds.

Kadrmas, K. A.↗