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Proceedings Paper

Measuring the displacement of the movable guard electrode in the new vertical calculable capacitor at NIM
Author(s): Jianbo Wang; Jin Qian; Zhongyou Liu; Xiuying Liu; Zhuliang Lu; Lu Huang; Cong Yin; Tongbao Li
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Paper Abstract

A new type vertical calculable capacitor has been built at National Institute of Metrology (NIM) cooperated with National Measurement Institute of Australia (NMIA). The calculable capacitor is the highest accuracy equipment apparatus except the quantum voltage and the quantum resistance in the electromagnetic metrological field. In order to measure the capacitance precisely, the accurate displacement measurement among the two guard electrodes in the calculable capacitor is a pivotal part. This paper describes a method of measuring the displacement of a Fabry-Perot interferometer, and this interferometer is component of two mirrors in two guard electrodes of the calculable capacitor at NIM. One concave reflective mirror, with 5 m radius and 70% reflectivity, is on the top of the bottom fixed guards electrodes. The other planar mirror is placed at the end of the moveable guard electrodes. This Fabry-Perot interferometer employs a home-made lamb-dip stabilization He-Ne laser at 633 nm to measure the displacement of the movable guard electrode. The internal modulation, which is used for laser stabilization, is also employed for locking the Fabry-Perot interferometer. The displacement of the movable guard electrode could be measured, when the Fabry-Perot interferometer is locked to the stabilization laser at two positions respectively. An iodine stabilization He-Ne laser at 633 nm is employed to simultaneously calibrate the wavelength of lamb-dip working laser. A reproducibility of 1.43×10-8(k=3) for the range of 205 mm can be obtained at present, and that is estimated from the experimental results of calculable capacitor.

Paper Details

Date Published: 13 November 2014
PDF: 5 pages
Proc. SPIE 9276, Optical Metrology and Inspection for Industrial Applications III, 92761R (13 November 2014); doi: 10.1117/12.2071812
Show Author Affiliations
Jianbo Wang, Tongji Univ. (China)
National Institute of Metrology (China)
Jin Qian, National Institute of Metrology (China)
Zhongyou Liu, National Institute of Metrology (China)
Xiuying Liu, National Institute of Metrology (China)
Zhuliang Lu, National Institute of Metrology (China)
Lu Huang, National Institute of Metrology (China)
Cong Yin, National Institute of Metrology (China)
Tongbao Li, Tongji Univ. (China)


Published in SPIE Proceedings Vol. 9276:
Optical Metrology and Inspection for Industrial Applications III
Sen Han; Toru Yoshizawa; Song Zhang, Editor(s)

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