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:
Nov. 19, 2002
Filed:
Oct. 27, 1999
John W. Sadler, Belmont, CA (US);
Kenneth L. Staton, San Carlos, CA (US);
Agilent Technologies, Inc., Palo Alto, CA (US);
Abstract
An inner control loop controls the relative position of a surface to be scanned with respect to a focal plane. An outer control loop responds to the location of the surface to be scanned with respect to a focal plane of the scan lens to generate a setpoint for the inner control loop. A sample-and-hold element disposed between the inner and outer control loops is switched by an edge or defect detector. It is preferred that the outer control loop has a time constant in the range of three to ten times longer than that of the inner control loop. The sample-and-hold element provides a gradual state transition upon the occurrence of an edge or a surface defect.