Comparison of photo detectors and operating conditions for decay time determination in phosphor thermometry

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Abstract

This work compares the extent of linear response regions from standard time-resolving optical detectors
for phosphor thermometry. Different types of photomultipliers (ordinary and time-gated) as
well as an avalanche photodiode were tested and compared using the phosphorescence decay time of
cadmium tungstate (CdWO4). Effects originating from incipient detector saturation are revealed as a
change in evaluated phosphorescence decay time, which was found to be a more sensitive measure for
saturation than the conventional signal strength comparison between in- and output. Since the decay
time of thermographic phosphors is used for temperature determination systematic temperature errors
in the order of several tens of Kelvins may be introduced. Saturation from the initial intensity is isolated
from temporally developed saturation by varying the CdWO4 decay time over the microsecond
to nanosecond range, resultant of varying the temperature from 290 to 580 K. A detector mapping procedure
is developed in order to identify linear response regions where the decay-to-temperature evaluations
are unbiased. In addition, this mapping procedure generates a library of the degree of distortion
for operating points outside of linear response regions. Signals collected in the partly saturated regime
can thus be corrected to their unbiased value using this library, extending the usable detector operating
range significantly. © 2012 American Institute of Physics.

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  • Atom and Molecular Physics and Optics
Original languageEnglish
Article number094901
JournalReview of Scientific Instruments
Volume83
Issue number9
Publication statusPublished - 2012
Publication categoryResearch
Peer-reviewedYes

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