Spectrometric Temperature Measurement Using a Zinc Selenide-Based Fiber-Optic Sensor

An extrinsic fiber-optic sensor for temperature monitoring based on the spectral shift of ZnSe has been developed. The calibration model is based on wavelength position data rather than intensity, eliminating the need for measurement of the input light intensity and making it robust with respect to lamp and detector fluctuations. The wavelength accuracy necessary to obtain quality results with this method was achieved on a low-cost spectrometer by combining the sensor output with light from a mercury lamp that enabled realtime correction data to be acquired simultaneously with the spectral shift of the ZnSe. The results on this economically priced system were similar to those from a more expensive, more wavelength stable spectrometer that did not require wavelength correction. In both cases, the standard error of prediction (SEP) for temperatures in the 25–70 °C range was initially around 0.2 °C. After two weeks, the SEP increased to around 0.4–0.5 °C.