Instrument of Fluorescence Thermal Measurement Based on Fast Fourier Transform

A sapphire fiber thermal probe with Cr~(3+)ion-doped end is grown from the laser heated pedestal growth method.The fluorescence thermal probe offers advantages of compact construct,high performance and ability to withstand high temperature among the detection range from the room temperature to 450 ℃.Basing on the fast Fourier transform(FFT).The fluorescence lifetime is obtained from the tangent function of the phase angle of the first non-zeroth items of the FFT result.This method has advantages such as quick calculation,high accuracy and immunity to the base signal.Comparing with other traditional fitting methods,the standard deviation of the FFT method is about half of the standard deviation of the Prony method and near that of the Marquardt method.In addition,the FFT method is immunity to the background noise of the signal,so that the process of signal processing by the FFT method can be advanced.