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Proceedings Paper

PZT local linearity and image sampling strategy for white-light vertical scanning measurement
Author(s): X. Liu; J. Li; W. Lu
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Paper Abstract

White-light vertical scanning technique has been used for surface topography measurement because of its characteristics of non-contact, high-accuracy and large range. In this technique, PZT is usually employed for high resolution vertical scanning. Due to the nonlinearity and creep characteristics of PZT however, large scanning positioning error is inevitable if direct interference image sampling without positioning metrology is adopted. Otherwise if positioning metrology is adopted for every image sampling, measurement efficiency will be reduced greatly. To solve this problem in this paper, the nonlinearity characteristic of PZT is analyzed and its local linearity is investigated, and based on the local linearity a novel interference image sampling strategy is proposed. In this strategy, the whole scanning range is divided into many sub-ranges, in which the non-linearity errors are small enough for direct interference image sampling. When white-light vertical scanning measurement is conducted, in every sub-range, interference images are sampled directly at every scanning position corresponding to equal driving voltage interval of PZT, while the end points of each sub-range are measured by a positioning metrology system. Thus based on the local linearity of sub-range, the scanning positioning for image sampling can have enough accuracy, while less positioning metrology is needed for high measurement efficiency. Analysis and case study proves the improved scanning positioning accuracy and measurement efficiency through the novel sampling strategy.

Paper Details

Date Published: 15 November 2011
PDF: 7 pages
Proc. SPIE 8321, Seventh International Symposium on Precision Engineering Measurements and Instrumentation, 83213N (15 November 2011); doi: 10.1117/12.905349
Show Author Affiliations
X. Liu, Huazhong Univ. of Science and Technology (China)
J. Li, Huazhong Univ. of Science and Technology (China)
W. Lu, Huazhong Univ. of Science and Technology (China)

Published in SPIE Proceedings Vol. 8321:
Seventh International Symposium on Precision Engineering Measurements and Instrumentation
Kuang-Chao Fan; Man Song; Rong-Sheng Lu, Editor(s)

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