光纤荧光传感器衰减寿命的加权对数拟合法

荧光寿命的检测是荧光光学传感器的核心内容，国际上尝试了多种方法来拟合这种理论上为单指数衰减信号的荧光衰减曲线。这些方法包括非线性函数标准拟合方法。即Levenburg-Marquardt方法，以及Prony方法、FFT方法，对数拟合法等等。为了克服在实际应用中发生的信号退化，需要在测量信号衰减寿命的同时测量信号的初始强度。文章介绍了一种加权的对数拟合法，经计算机仿真及实际数据测试均可以得到和Levenburg-Marquardt方法非常接近的结果，且拟合时间大大缩短，测量稳定性大大提高。仿真测试及具体实验测试结果显示了这种方法的有效性。该方法不仅与Levenburg-Marquardt方法的偏差曲线非常相似，而且实验测得的荧光寿命与Levenburg-Marquardt方法偏差在0．2％以内。

Weighted Log-fit Method for Measuring Decay Time of Optical Fiber Fluorescence Sensors

Measurement of the fluorescence-decay time is the key technique of the fluorescence optical sensors. Some methods are attempted to fit the fluorescence decay curve, which theoretically is a single-exponential decay. The standard non-linear-function fitting method, the Levenburg-Marquardt method, is one of them. Besides it, the Prony method, FFT method, log-fit method can be used to estimate the fluorescence-decay time. To overcome the signal decline in a real system, the initial intensity of the signal should be measured with the decay lifetime. A new logarithm estimation method with weight (termed as the weighted log-fit method) is proposed. The results obtained by this method are very similar to those by Levenburg-Marquardt method. In addition, the new method is much quicker and stable than the Levenburg-Marquardt method. The simulative and experimental results show the effec-tiveness of this method. The deviation curve of this new method is very similar to that of the Levenburg-Marquardt method. The difference between the fluorescence-decay times measured under these two methods is less than 0.2 % in the experiments.