Image analysis – Image transformation or preprocessing – Fourier transform
Reexamination Certificate
2006-08-22
2006-08-22
Patel, Kanjibhai (Department: 2627)
Image analysis
Image transformation or preprocessing
Fourier transform
C250S201300, C250S201700, C144S145300, C144S255000, C144S278100
Reexamination Certificate
active
07095904
ABSTRACT:
A method and apparatus (10) for determining a best focus position of an object (30) relative to a reference position (e.g., axis A) of a dark-field optical imaging system (20), with an effective focusing range up to 10 times of the depth of field of the system. The method includes the steps of first forming a dark-field image of the object at different focus positions (zm). Each dark-field image has a corresponding image intensity distribution with an average intensity and a variance of intensity. The next step is forming a set of contrast values by calculating a contrast value (Cm) for each dark-field image based on the variance and the average intensity. The last step is determining the best focus position by fitting a Lorentzian function to the set of contrast values plotted as a function of the different focus positions and identifying the focus position associated with the maximum contract value (Cmax). The second step includes digitizing each dark-field image such that the image intensity distribution for each the dark-field image is a digitized image intensity distribution comprising discrete gray-scale intensity levels (In) corresponding to a discrete plurality of n pixels, and then arranging each the digitized image intensity distribution into a histogram (H(In)) of an amount of the pixels having a given the gray-scale intensity level (In).
REFERENCES:
patent: 4549084 (1985-10-01), Markle
patent: 4952970 (1990-08-01), Suzuki et al.
patent: 5369430 (1994-11-01), Kitamura
patent: 5552594 (1996-09-01), Vandenberg et al.
patent: 5650621 (1997-07-01), Tsuneta et al.
patent: 6268093 (2001-07-01), Kenan et al.
patent: 6407373 (2002-06-01), Dotan
patent: 6940585 (2005-09-01), Nomura et al.
Desire Gregory
Jones Allston L.
Patel Kanjibhai
Ultratech, Inc.
LandOfFree
Method and apparatus for determining best focus using... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for determining best focus using..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for determining best focus using... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3639687