The analysis of logarithm fitting method for measuring decay time of optical fiber fluorescence sensors

The logarithm fitting method, due to its simple principle, quick operational speed and accepted accuracy, is widely used to measure the decay time of the fluorescence temperature or pH value sensors. Using logarithm fitting method, the unavoidable random noise of the acquired signal causes the random fitting error of the decay time. In addition, we found that the random noise will lead a systemic deviation of the fitting decay time. The higher the noise level is, the smaller the fitting decay time is. Based on analysis and simulation, we explained the reason of systemic deviation of the decay time of a single-exponential decay with random noise and gave a modified method.