Research And Realization Of Key Technology Of Fluorescent Optical Fiber Temperature Sensor

In industrial production,military,medical and other fields,real-time online monitoring of temperature parameters is needed.In particular,the fields of military and medical have higher requirements for the accuracy of temperature detection.However,traditional active temperature sensors(thermocouples)are susceptible to interference from the electrical signals of other military equipment and strong electromagnetic fields in the external environment in the above-mentioned harsh areas,and the temperature measurement accuracy and stability cannot be guaranteed.Therefore,it is necessary to study the high-precision fluorescent optical fiber temperature sensor with complete insulation.Firstly,this paper compares and analyzes the principle and advantages of three optical fiber fluorescence temperature measurement systems,and finally the fluorescence lifetime optical fiber temperature sensor is selected as the research focus.Then,the key technologies such as hardware circuit,software and data processing algorithm of the system are deeply studied and designed,and the principle prototype of fluorescent optical fiber temperature sensor is realized.The main contents of this paper are as follows:1.In order to ensure the integrity and consistency of the fluorescence signal,the driving circuit of the light-emitting diode(LED)and the amplification circuit of the fluorescence signal are studied and designed in this paper.The LED drive circuit is based on pulse width modulation and negative feedback,which realizes the periodic modulation of the light source and the indirect regulation of the intensity of the fluorescent signal.The negative feedback scheme can reduce the influence of the fluctuation of the fluorescence intensity on the temperature measurement accuracy of the system.In order to ensure that the amplifier circuit works in the linear region,the static working voltage of the amplifier circuit is corrected by negative feedback technology.The negative feedback scheme can avoid cut-off distortion or saturation distortion of the fluorescent signal.2.The calculation accuracy of fluorescence lifetime depends on sampling interval and data processing algorithm.In this paper,a timer is used to trigger Analog-to-Digital Converter(ADC)sampling,and Direct Memory Access(DMA)is configured to transmit the sampling data,so that the sampling interval is equal.In the data processing algorithm,a new weighted linear least squares fitting algorithm is implemented in this paper.The algorithm does not need to set the initial guess value.Experimental results show that the accuracy of the algorithm is improved by about 65.5%compared with the weighted linear least squares fitting algorithm without improvement,and the response time of the data processing algorithm is reduced by about 36.5%.3.Based on the principle of correlation between fluorescence lifetime and temperature,the circuit,software and data processing algorithm of the system are designed,and the principle prototype of fluorescence fiber temperature sensor is realized.The test data shows that the fluorescence lifetime has a good linearity with temperature.In the temperature range of25? to 100?,the best temperature measurement accuracy of the system is about ±0.1?.