Laser Focus World - January 2015

Optical Sensor Solutions

First Sensor provides in-house design, manufacturing and testing of sensor solutions for all needs. Light sensors include UV, visible light and infrared detectors, emitters as laser diodes and LEDs as well as optoelectronic modules. All options can be provided as standard, custom, hybrid and integrated solutions.

call 818 706-3400 contact.us@first-sensor.com www.first-sensor.com Sensor solutions by First Sensor Come and visit us at Photonics West 2015, Booth 2517

Standard products available through www.mouser.com

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InGaN-based nanowire LEDs emit different colors depending on nanowire properties. A three-color LED pixel (top center); single-color LEDs emit (counterclockwise from left) red, yellow, green, and blue-green. (Courtesy McGill University)

NITRIDE LEDS

Multicolor InGaN nanowire LED
arrays span the visible spectrum

Indium gallium nitride (InGaN)-based
LEDs have revolutionized the lighting and
other industries, leading to high-power
white-light LEDs, among other achieve-
ments. However, due to properties of
bulk InGaN, conventional InGaN LEDs
can only be made to emit light at wave-
lengths between the UV and the green
spectral regions; other LED colors are
achieved either by the use of phosphor or
by the addition of other LEDs of different
composition (for example, indium gallium
aluminum phosphide
red-emitting LEDs).
Now, research-
ers at McGill Univer-
sity (Montreal, QC
Canada), New Jersey
Institute of Technology
intensified active-pixel sensor (IAPS) of
the UV-imaging detector are compared
to previously imaged radiance values
from the selected UV-emitting stars,
and associated conversion factors are
computed. The UV transmission must
also be calibrated against the vignett-
ing function of the telescope, the reflec-
tivity of its mirrors, the interference-fil-
ter transmissivity, the detector quantum
efficiency, and the telescope point-spread
function as produced by optics on the
UV focal plane.

These in-flight observations are then compared to predicted/previously measured data to perform radiometric calibration, allowing the instrument to monitor system throughput and track intensity variations that could be caused by optical contamination or degradation due to outgassing or cosmic radiation (mainly protons) that characterize the harsh space environment in which Solar Orbiter shall operate. In addition to using UV-emitting stars, UV emission from other suitable sources (such as planets)

could also be used if they fall in the field of view of METIS during its coronal observations.

“Solar Orbiter will be a very exciting mission, leading to a deep knowledge of our Star and its atmosphere— responsible for our daily life,” says Mauro Focardi, a Young Scientist fellow at the INAF-OAA Arcetri Astrophysical Observatory. “At present, our research group is also working on the development of new technologies based on nanostructures to perform UV-imaging polarimetry in the HI Lyman-alpha line. This would provide, for the first time, the capabilities to perform diagnostics on the hot coronal plasma, measuring the magnetic fields defining the thin coronal structures and following the Hanle effect rules.” — Gail Overton

REFERENCE

1. Mauro Focardi, et al., SPIE Newsroom; doi: 10.1117/2.1201411.005684 (December 1, 2014) or see http://spie.org/x110915.xml?hig hlight=x2418&ArticleID=x110915