Photonics/Optics

Multiple-Event, Single-Photon Counting Imaging Sensor

This sensor has applications in high-energy physics and medical and biological imaging systems. The single-photon counting imaging sensor is typically an array of silicon Geiger-mode avalanche photodiodes that are monolithically integrated with CMOS (complementary metal oxide semiconductor) readout, signal processing, and addressing circuits located in each pixel and the peripheral area of the chip. The major problem is its “single-event” method for photon count number registration. A single-event single-photon counting imaging array only allows registration of up to one photon count in each of its pixels during a frame time, i.e., the interval between two successive pixel reset operations. Since the frame time can’t be too short, this will lead to very low dynamic range and make the sensor merely useful for very low flux environments. The second problem of the prior technique is a limited fill factor resulting from consumption of chip area by the monolithically integrated CMOS readout in pixels. The resulting low photon collection efficiency will substantially ruin any benefit gained from the very sensitive single-photon counting detection.

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

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Qualification of Fiber Optic Cables for Martian Extreme Temperature Environments

Means have been developed for enabling fiber optic cables of the Laser Induced Breakdown Spectrometer instrument to survive ground operations plus the nominal 670 Martian conditions that include Martian summer and winter seasons. The purpose of this development was to validate the use of the rover external fiber optic cabling of ChemCam for space applications under the extreme thermal environments to be encountered during the Mars Science Laboratory (MSL) mission.

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

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Transverse Pupil Shifts for Adaptive Optics Non-Common Path Calibration

A simple new way of obtaining absolute wavefront measurements with a laboratory Fizeau interferometer was recently devised. In that case, the observed wavefront map is the difference of two cavity surfaces, those of the mirror under test and of an unknown reference surface on the Fizeau’s transmission flat. The absolute surface of each can be determined by applying standard wavefront reconstruction techniques to two grids of absolute surface height differences of the mirror under test, obtained from pairs of measurements made with slight transverse shifts in X and Y.Adaptive optics systems typically provide an actuated periscope between wavefront sensor (WFS) and common-mode optics, used for lateral registration of deformable mirror (DM) to WFS. This periscope permits independent adjustment of either pupil or focal spot incident on the WFS. It would be used to give the required lateral pupil motion between common and non-common segments, analogous to the lateral shifts of the two phase contributions in the lab Fizeau.

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

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Solid-State Spectral Light Source System

A solid-state light source combines an array of light-emitting diodes (LEDs) with advanced electronic control and stabilization over both the spectrum and overall level of the light output. The use of LEDs provides efficient operation over a wide range of wavelengths and power levels, while electronic control permits extremely stable output and dynamic control over the output.

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

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3D Imaging Technology Changing the Way We Look at Things

Everywhere we look we are bombarded with 3D. It’s in movies, in-home entertainment, digital camcorders, gaming systems, laptops, and even in our labs. What is it about 3D that is so fascinating and what are some of the technology drivers that are determining its future?

Posted in: Articles, Features, ptb catchall, Photonics

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Creating 3D Terrain Maps from 2D Data

Disaster relief workers, border patrol officers, wildfire fighters, and many others need up-to-date information about what they will see when they enter an area, not just sketchy topographic maps that may be years out of date. For them, things change in a hurry, and high-resolution details may be critical to their mission success.

Posted in: Articles, Applications, Features, ptb catchall, Photonics

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Tunable Laser Module and Fast Spectral Loss Engine

Agilent Technologies (Santa Clara, CA) has introduced a compact tunable laser module for its 816x Series lightwave measurement platform. The Agilent 81960A module, which features a 200 nm/s sweep speed and increased acceleration, measures dense-wavelength division multiplexing (DWDM) components. The 81960A offers C- and L-band wavelength coverage for DWDM component measurements; it also provides bidirectional sweeping and 1-3 Hz repetition rate, depending on range. Automated measurements are supported by N7700A measurement engines, an updated 816x plug-and-play driver, N4150A photonic foundation library, and direct SCPI commands. The 81960A features up to +14 dBm output power, adjustable down to +6 dBm.

Posted in: Products, Products, ptb catchall, Photonics

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