Defocus measurement for random self-affine fractal surfaces.
We studied correlation between fractal dimensions and image contrast for metallic surfaces. The study has led to an interesting finding that the maximum fractal dimension of the object surface under imaging gives the best focal plane. The significant finding can be made use of to estimate the best focal plane or measure the focus error with high sensitivity of a few microns, which are well within depth of field of the microscopic imaging system.
Precision Engineering and Nanotechnology Centre School of Mechanical and Aerospace Engineering Nanyang Technological University, Singapore 639798. jwang@ntu.edu.sg
Jun
J
Wang
Wei
W
Zhou
Lennie E
LE
Lim
Anand K
AK
Asundi
D000465:Algorithms; D003198:Computer Simulation; D017709:Fractals; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008670:Metals / Q000737:chemistry*; D008853:Microscopy / Q000379:methods*; D015233:Models, Statistical; D013499:Surface Properties
D008670:Metals