暗电流作为光电探测器的固有噪声，是影响双光束分光光度计检测性能的重要因素。为消除此影响，提出自适应滤波双光束分光光度计。首先，设计实时暗电流检测系统，能在每个检测周期内捕获样品信号、参考信号和暗电流信号。其次，针对时域差异引起的暗电流消除问题，引入自适应级联滤波算法(Recursive Least Squares and Normalized Least Mean Squares，RLS-NLMS)，算法采用三级级联滤波模型，一级局部均值(Lo-cal Mean，LM)降低暗电流与检测信号之间的相关性，二级低阶RLS滤波器用于检测信号滤波，三级高阶NLMS滤波器用于处理RLS输出信号。实验结果显示，自适应滤波双光束分光光度计的透射比相对误差仅为1。46％，较传统方法降低了 66％，在暗电流消除方面表现出色，具有实际应用价值。
Dark current elimination design based on adaptive filtering
Dark current,as an inherent noise in photodetectors,significantly affects the detection performance of dual-beam spectrophotometers.To mitigate this impact,an adaptive filtering dual-beam spectrophotometer is pro-posed.Firstly,a real-time dark current detection system is designed to capture the sample signal,reference signal,and dark current signal within each detection cycle.Secondly,an adaptive cascaded filtering algorithm called Recur-sive Least Squares and Normalized Least Mean Squares(RLS-NLMS)is introduced to address the issue of dark cur-rent elimination caused by temporal differences.The algorithm employs a three-level cascaded filtering model.The first level,local mean(LM),reduces the correlation between dark current and the detection signal.The second level utilizes a low-order RLS filter for signal filtering,while the third level employs a high-order NLMS filter to process the output signal from RLS.Experimental results demonstrate that the adaptive filtering dual-beam spectrophotometer a-chieves a relative error of only 1.46％in transmittance ratio measurement,reducing it by 66％compared to traditional methods.It exhibits excellent performance in dark current cancellation and holds significant practical value.
dark currentdouble beam spectrophotometerphotodetectorspectroscopic systemcascade filtering
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