中文摘要：

分析了LED芯片非接触检测系统噪声信号的功率谱，研究了噪声信号的抑制方法。针对现有检测系统存在检测信噪比低的不足，提出对交变电压信号进行相关检测，采用相关检测后，检测系统的信噪比可以提高20dB以上。实验结果与仿真结果吻合。该研究对于改进检测系统的性能以满足对多种芯片的正确检测有重要意义。

英文摘要：

The noise power spectra of the non-contact detection system for LED chips and the noise suppression methods are discussed. As the detection system has the deficiency of low signal-to-noise ratio, the alternating signal is processed by the method of correlation detection. By using this method, the signal-tonoise ratio of the system can be increased by 20dB or more. The experimental results and simulation results are well in agreement with each other. This is very important for improving the system performance on correctly detecting more kinds of chips.