Eddy current displacement sensor with ultrahigh resolution obtained through the noise suppression of excitation voltage

摘要

This paper presents a method for heightening the resolution of an eddy current sensor (ECS). A typical ECS based on AC bridge and orthogonal phase sensitive detector is used to explain the principle and is verified with experiments. For this type of ECS, the noise in the excitation voltage applied on the bridge is considered to have an important influence on the sensor's resolution. A high-Qpassive LC bandpass filter used for depressing the noise in the excitation voltage is designed and analyzed. Experimental results show that the sensor's resolution is greatly improved with the help of the filter. With a working range of 20 mu m and a bandwidth of 7.2 Hz, the sensor's resolution is heightened from 0.35 nm(rms) to 0.05 nm(rms). (C) 2019 Elsevier B.V. All rights reserved.