Proceedings Article | 24 August 2009
KEYWORDS: Temperature metrology, Sensors, Black bodies, Wavelets, Signal processing, Optical fibers, Signal detection, Optical filters, Interference (communication), Calibration
High temperature is one of the most important parameters in the fields of scientific research and industrial production. At
present, thermocouple, thermo resistive and radiance thermometer are already technologically mature which can be
adopted to measure the general temperature, but when it comes to the transient high temperature that changes pretty
quickly in wretched conditions, those traditional pyrometers can not meet the requirements any more. In this paper, we
designed a transient optical high temperature measurement system. First, design of the temperature measurement probe.
The system took blackbody cavity sensor together with optical fiber to receive the measured signal, here, the integrated
emissivity model of the blackbody cavity was established and the optimum structure parameters were confirmed.
Secondly, design of the entire temperature measurement system. A contact-noncontact measurement method was
applied, which is to make the blackbody cavity and the measured high-temperature source contact, the fiber probe and
the blackbody cavity noncontact, as a result, the error caused by contact measurement is overcame and the precision is
guaranteed at the same time. In addition, a fiber grating was introduced as the wavelength filter device which can realize
the dynamic filter of narrow-band signals and reduce the impact of background light. Thirdly, signal processing. In this
part, we applied labVIEW software and wavelet analysis method. All of the signal acquisition and processing were
realized in the labVIEW environment. Through calling matlab in labVIEW, the signals from optical fiber detector were
wavelet denoised and decomposed, thus the temperature information was extracted, and the temperature value was
obtained. On basis of wavelet transformation, the paper adopted the 4dB wavelet with horizontal scale of 5 to realize the
feature extraction and noise removal, parts of the signals before and after the wavelet noise removal were given and
analyzed. Finally, the experimental result shows: the resolution is 1°C,the measurement range is 500~2000°C and the
dynamic response time is 5s.In view of possessing a high precision and resolution, resisting high temperature and
corrosion, and being able to realize the continuous measurement of the dynamic temperature, this transient optical fiber
high temperature measurement system can be applied widely in the continuous temperature measurement of molten steel
and heating furnace kiln temperature measurement and so many other fields of engineering technology.
