@article{CHEN2017, 
author = {Xi CHEN and Jun CHANG and Fupeng WANG and Zongliang WANG and Wei WEI and Yuanyuan LIU and Zengguang QIN},
title = {A portable analog lock-in amplifier for accurate phase measurement and application in high-precision optical oxygen concentration detection},
year = {2017},
journal = {Photonic Sensors},
volume = {7},
number = {1},
pages = {27-36},
keywords = {Portable analog lock-in amplifier, phase shift measurement, high accuracy, optical oxygen detection},
url = {https://www.sciopen.com/article/10.1007/s13320-016-0335-7},
doi = {10.1007/s13320-016-0335-7},
abstract = {A portable analog lock-in amplifier capable of accurate phase detection is proposed in this paper. The proposed lock-in amplifier, which uses the dual-channel orthometric signals as the references to build the xy coordinate system, can detect the relative phase between the input and x-axis based on trigonometric function. The sensitivity of the phase measurement reaches 0.014degree, and a detection precision of 0.1degree is achieved. At the same time, the performance of the lock-in amplifier is verified in the high precision optical oxygen concentration detection. Experimental results reveal that the portable analog lock-in amplifier is accurate for phase detection applications. In the oxygen sensing experiments, 0.058% oxygen concentration resulted in 0.1degree phase shift detected by the lock-in amplifier precisely. In addition, the lock-in amplifier is small and economical compared with the commercial lock-in equipments, so it can be easily integrated in many portable devices for industrial applications.}
}