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On the automation of thermographic phosphor calibration

Abou Nada, Fahd Jouda LU ; Knappe, Christoph LU ; Xu, Xin; Richter, Mattias LU and Aldén, Marcus LU (2014) 60th International Instrumentation Symposium In Proceedings of the 60th International Instrumentation Symposium
Abstract
Thermographic phosphors can be robust temperature remote sensors. The accuracy of the temperature measured by the phosphor is highly dependent on the quality of the phosphor calibration used. Conventionally, thermographic phosphors are calibrated by measuring a series of decay curves at known stable oven temperatures. The process is then repeated covering the thermal sensitivity range of the phosphor chosen. Heating and cooling rates of high temperature ovens are usually low. Also, thermal equilibrium of the system is required at each calibration temperature before acquiring luminescence decay curves. Thus, the process is usually time consuming and the number of calibration points achieved is limited to a couple of dozen points. This study... (More)
Thermographic phosphors can be robust temperature remote sensors. The accuracy of the temperature measured by the phosphor is highly dependent on the quality of the phosphor calibration used. Conventionally, thermographic phosphors are calibrated by measuring a series of decay curves at known stable oven temperatures. The process is then repeated covering the thermal sensitivity range of the phosphor chosen. Heating and cooling rates of high temperature ovens are usually low. Also, thermal equilibrium of the system is required at each calibration temperature before acquiring luminescence decay curves. Thus, the process is usually time consuming and the number of calibration points achieved is limited to a couple of dozen points. This study presents and validates the development of an automatic routine for the calibration of thermographic phosphors. It was designed to continuously and simultaneously acquire phosphor decay curves along with their corresponding thermocouple temperatures. The developed routine required software and hardware improvements. An updated design of the calibration substrate was implemented to improve the thermal conditions during calibration. Thermal gradients were further studied using a heat transfer model. The routine implemented a specially designed sparsing algorithm that reduced the sampling rate of the decaying luminescence curve without influencing the calculated decay time. The upper heating rate is set at 4 K.min-1 due to limitation imposed by the ceramic calibration oven. The phosphors CdWO4 and Mg3F2GeO4:Mn were chosen to validate the finalized routine. After the completion of the calibration process, a library-based calibration is created as the final product. The automated calibration routine delivered an overall accuracy improvement of 1-2 K, reduced calibration duration by factor of four and provided the possibility of deriving signal recognition algorithms. The condensed calibration dataset produced by the proposed calibration routine was further employed to develop a novel signal shape recognition algorithm for temperature evaluation. (Less)
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author
organization
publishing date
type
Chapter in Book/Report/Conference proceeding
publication status
in press
subject
keywords
thermographic phosphors, calibration, thermometry.
in
Proceedings of the 60th International Instrumentation Symposium
pages
6 pages
publisher
Institution of Engineering and Technology
conference name
60th International Instrumentation Symposium
language
English
LU publication?
yes
id
95ee23c0-84a8-4647-9fa0-f1a15d0fb6c0 (old id 4530120)
date added to LUP
2014-07-04 09:46:32
date last changed
2016-10-05 07:51:56
@misc{95ee23c0-84a8-4647-9fa0-f1a15d0fb6c0,
  abstract     = {Thermographic phosphors can be robust temperature remote sensors. The accuracy of the temperature measured by the phosphor is highly dependent on the quality of the phosphor calibration used. Conventionally, thermographic phosphors are calibrated by measuring a series of decay curves at known stable oven temperatures. The process is then repeated covering the thermal sensitivity range of the phosphor chosen. Heating and cooling rates of high temperature ovens are usually low. Also, thermal equilibrium of the system is required at each calibration temperature before acquiring luminescence decay curves. Thus, the process is usually time consuming and the number of calibration points achieved is limited to a couple of dozen points. This study presents and validates the development of an automatic routine for the calibration of thermographic phosphors. It was designed to continuously and simultaneously acquire phosphor decay curves along with their corresponding thermocouple temperatures. The developed routine required software and hardware improvements. An updated design of the calibration substrate was implemented to improve the thermal conditions during calibration. Thermal gradients were further studied using a heat transfer model. The routine implemented a specially designed sparsing algorithm that reduced the sampling rate of the decaying luminescence curve without influencing the calculated decay time. The upper heating rate is set at 4 K.min-1 due to limitation imposed by the ceramic calibration oven. The phosphors CdWO4 and Mg3F2GeO4:Mn were chosen to validate the finalized routine. After the completion of the calibration process, a library-based calibration is created as the final product. The automated calibration routine delivered an overall accuracy improvement of 1-2 K, reduced calibration duration by factor of four and provided the possibility of deriving signal recognition algorithms. The condensed calibration dataset produced by the proposed calibration routine was further employed to develop a novel signal shape recognition algorithm for temperature evaluation.},
  author       = {Abou Nada, Fahd Jouda and Knappe, Christoph and Xu, Xin and Richter, Mattias and Aldén, Marcus},
  keyword      = {thermographic phosphors,calibration,thermometry.},
  language     = {eng},
  pages        = {6},
  publisher    = {ARRAY(0xb4dbc58)},
  series       = {Proceedings of the 60th International Instrumentation Symposium},
  title        = {On the automation of thermographic phosphor calibration},
  year         = {2014},
}