A new capacitive long-range displacement nanometer sensor with differential sensing structure based on time-grating. (10th April 2018)

• Record Type: Journal Article
• Authors: Yu, Zhicheng; Peng, Kai; Liu, Xiaokang; Pu, Hongji; Chen, Ziran
• Is Part Of: Measurement science & technology. Volume 29:Number 5(2018:May)
• Publication Date: 2018-04-10
• Subjects: nanometer measurement -- capacitive displacement sensor -- long-range -- time-grating -- differential sensing structure; Physical measurements -- Periodicals; Scientific apparatus and instruments -- Periodicals; Equipment and Supplies -- Periodicals; Science -- instrumentation -- Periodicals; Technology -- instrumentation -- Periodicals; Mesures physiques -- Périodiques; Physical measurements; Scientific apparatus and instruments; Periodicals; 502.87
• DOI: 10.1088/1361-6501/aaaf05
• Languages: English
• ISSNs: 0957-0233

Abstract

Abstract: High-precision displacement sensors, which can measure large displacements with nanometer resolution, are key components in many ultra-precision fabrication machines. In this paper, a new capacitive nanometer displacement sensor with differential sensing structure is proposed for long-range linear displacement measurements based on an approach denoted time grating. Analytical models established using electric field coupling theory and an area integral method indicate that common-mode interference will result in a first-harmonic error in the measurement results. To reduce the common-mode interference, the proposed sensor design employs a differential sensing structure, which adopts a second group of induction electrodes spatially separated from the first group of induction electrodes by a half-pitch length. Experimental results based on a prototype sensor demonstrate that the measurement accuracy and the stability of the sensor are substantially improved after adopting the differential sensing structure. Finally, a prototype sensor achieves a measurement accuracy of ±200 nm over the full 200 mm measurement range of the sensor.