Sapphire fiber thermal probe based on wavelet transform

A sapphire fiber fluorescence thermal probe with Cr3+iondoped end was grown from the laser heated pedestal growth method. The fluorescence thermal probe offers the advantages of compact in structure, high performance and ability to detect temperature ranging from the room temperature to 450℃. The data processing based on the wavelet transform can effectively decrease the noise out of the signal so that the signaltonoise ratio can be improved. Based on the theoretical analysis of the fluorescence temperature measurement methodology and fiber technology, a phaselock loop technology is adopted to make the realtime measurement without the interference of the exciting light. Taking advantage of the different features indicated by noise and signal when wavelet transformation is applied, the temperature signal extraction and noise elimination method based on the wavelet transformation theory is given. In comparison with other processing methods, the wavelet transform method overcomes the shortcoming in the fast Fourier transform and can be applied to mutation signals, and it has a variable window that the Gabor transform does not has. Therefore, the method can shorten the process of signal processing and improve the measurement resolution.