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Optical Engineering

Stimulation of visible luminescence by irradiation of a novel phosphor screen with an infrared beam
Author(s): Robert Withnall; Jack Silver; Nicola Wilstead; Terry G. Ireland; George Robert Fern; David Klein; Stephen Bishton; Robert J. Rhodes
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Paper Abstract

A handheld gas detector is being developed that consists of a laser diode emitting light of wavelength equal to 1651 nm and an extended InGaAs detector. The IR laser beam is double-passed through a column of air via a folding mirror to a detector. The air column is in contact with the outside atmosphere so that low-relative-molecular-mass hydrocarbon gases, which diffuse into the air column, can be detected by the absorption of some of the IR light. The absorption at around 1651 nm is due to the overtones of C—H stretching vibrations and the limit of detection of the technique is at the parts per million level. One of the problems of using such a device in the field is that the operator cannot visualize the IR beam directly. Consequently, if the gas detection device fails to give a reading, the operator cannot be sure whether the laser is emitting light and the beam is correctly aligned. We describe the use of a novel phosphor screen to visualize the beam by converting the IR radiation into visible light. The properties of a number of phosphors that were developed and tested for the visualization of the beam are described. The merits of storage phosphors are compared to those of upconversion phosphors for use at this wavelength, which is longer than wavelengths previously visualized using upconversion phosphors.

Paper Details

Date Published: 1 February 2006
PDF: 9 pages
Opt. Eng. 45(2) 024001 doi: 10.1117/1.2172171
Published in: Optical Engineering Volume 45, Issue 2
Show Author Affiliations
Robert Withnall, Univ. of Greenwich (United Kingdom)
Jack Silver, Univ. of Greenwich (United Kingdom)
Nicola Wilstead, Univ. of Greenwich (United Kingdom)
Terry G. Ireland, Univ. of Greenwich (United Kingdom)
George Robert Fern, Univ. of Greenwich (United Kingdom)
David Klein, Semelab plc (United Kingdom)
Stephen Bishton, Semelab plc (United Kingdom)
Robert J. Rhodes, Semelab plc (United Kingdom)


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