The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 06, 1997
Filed:
Jun. 17, 1996
William A Keese, Philomath, OR (US);
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
A border of a circular specimen defining a high contrast feature is imaged. Multiple border portions are sampled at a magnification showing each portion as a straight edge. For alignment a location indicator signal is generated at each of minimum and maximum focal range. Image translation is detected from the two signals, and alignment automatically adjusted. The process repeats for subsequent border portions at a 90.degree. interval until image translation falls for a sample is less than a threshold. For astigmatism correction border portions are sampled about the entire specimen circumference at a 30.degree. interval. An axis of beam distortion is identified based upon a maximum image translation axis among the samples. Distortion is adjusted along such axis. Then, astigmatism connection signal strength is indexed and astigmatism correction is repeated iteratively until correction for a current iteration is less than a given threshold.