Open AccessFocus errors and their correction in microscopic deformation analysis using correlation
Author(s) -
Mark C. Pitter,
C. W. See,
Jason Y L Goh,
Michael Geoffrey Somekh
Publication year - 2002
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.10.001361
Subject(s) - subpixel rendering , optics , magnification , focus (optics) , displacement (psychology) , pixel , digital image correlation , deformation (meteorology) , microscope , interpolation (computer graphics) , sample (material) , image processing , materials science , physics , computer science , computer vision , image (mathematics) , psychology , composite material , psychotherapist , thermodynamics
Subpixel digital image correlation has been applied to microscope images to analyze surface deformation. Nonintegral pixel shifting and successive approximation are used to calculate the subpixel element of the sample displacement without introducing systematic interpolation errors. Although in-plane displacement precision of better than 2% of a pixel, or < 15 nm at x10 magnification, is shown to be achievable, the use of even moderate numerical aperture microscope objectives render the technique sensitive to errors or variations in sample focusing. The magnitude of this effect is determined experimentally and a focus compensation method is described and demonstrated.