Engine Oil Detection and Quantification Based on LED-IF Modulation-Demodulation Technology
WANG Xin-yi1, 2, MA Wei-xin1, 2, MA Chong-hao1, 2, WANG Wei3, QUAN Jia-xiang3, JI Zhong-hua1, 2*, ZHAO Yan-ting1, 2
1. Institute of Laser Spectroscopy Shanxi University, State Key Laboratory of Quantum Optics Technologies and Devices, Taiyuan 030006, China
2. Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
3. Wuxi Hymos Intelligent Technology Co., Ltd., Wuxi 214112, China
Abstract：To address the demand for engine oil leakage detection in mechanical manufacturing, this study proposes a high-sensitivity detection method combining LED-induced fluorescence (LED-IF) with modulation-demodulation technology, supported by quantitative analysis. A compact engine oil detection system operable under ambient natural light conditions was designed and implemented. Specifically, a 365 nm LED with an optical power of 20 mW at the output port was employed to excite engine oil samples, while a photodetector measured fluorescence emissions within the 410～460 nm range as the detection criterion. Optical filters and dichroic mirrors were utilized to purify the excitation light and fluorescence frequencies, effectively eliminating interference from ambient light sources on engine oil fluorescence signals. To further enhance sensitivity for weak fluorescence detection, modulation-demodulation technology was introduced to optimize system performance through parameter configuration of sliding filter window data volume, modulation amplitude, modulation frequency, and gain factor. This approach achieved a 70 dB improvement in signal-to-noise ratio compared to systems without modulation-demodulation. Based on the LED-IF modulation-demodulation framework, quantitative detection of engine oil volume and film thickness was investigated. Experimental results demonstrated a detection limit of 0.189 μL for engine oil volume at a 10 mm detection distance and a detection limit of 0.2 μm for engine oil film thickness on a water surface with a 32 mm inner diameter. These findings validate the effectiveness of the LED-IF modulation-demodulation technology in trace engine oil quantification and highlight its practical potential in natural light environments. Compared to conventional laser-induced fluorescence combined with spectrometer-based techniques, this solution offers a lower cost, a more compact footprint, and enhanced safety.
王馨懿，马伟鑫，马崇皓，王 伟，权家祥，姬中华，赵延霆. 基于LED诱导荧光和调制解调技术的机油检测及量化研究[J]. 光谱学与光谱分析, 2025, 45(10): 2790-2795.
WANG Xin-yi, MA Wei-xin, MA Chong-hao, WANG Wei, QUAN Jia-xiang, JI Zhong-hua, ZHAO Yan-ting. Engine Oil Detection and Quantification Based on LED-IF Modulation-Demodulation Technology. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2025, 45(10): 2790-2795.
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