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Proceedings Paper

Extended depth of field for visual measurement systems with depth-invariant magnification
Author(s): Yanyu Zhao; Yufu Qu
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Paper Abstract

Conventional optical imaging systems are limited by a fundamental trade-off between the depth of field (DOF) and signal-to-noise ratio. Apart from a large DOF, a constant magnification within a certain depth range is particularly essential for visual measurement systems. In this paper, we present a novel visual measurement system with extended DOF and depth-invariant magnification. A varifocal liquid lens is employed to sweep its focus within a single exposure of the detector, after which a blurred image is captured. The blurred image is subsequently reconstructed to form a sharp extended DOF image by filtering with a single blur kernel. The experimental results demonstrate that our method can extend the DOF of a conventional visual measurement system by over 10 times, while the change in the magnification within the extended DOF remains less than 1%.

Paper Details

Date Published: 20 November 2012
PDF: 8 pages
Proc. SPIE 8563, Optical Metrology and Inspection for Industrial Applications II, 85630O (20 November 2012); doi: 10.1117/12.999609
Show Author Affiliations
Yanyu Zhao, BeiHang Univ. (China)
Yufu Qu, BeiHang Univ. (China)

Published in SPIE Proceedings Vol. 8563:
Optical Metrology and Inspection for Industrial Applications II
Kevin G. Harding; Peisen S. Huang; Toru Yoshizawa, Editor(s)

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