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. 09, 1982
Filed:
Jan. 04, 1980
Applicant:
Inventors:
Assignee:
U.S. Philips Corporation, New York, NY (US);
Primary Examiner:
Int. Cl.
CPC ...
G01J / ;
U.S. Cl.
CPC ...
356123 ; 350170 ; 350172 ; 3501 / ; 369 45 ;
Abstract
A focussing error detection system is described for determining deviations between the plane of imaging of an objective system in an optical arrangement and the radiation-reflecting surface in said system. The apparatus comprises an optical element by means of which a radiation beam coming from the radiation reflecting surface is both rendered astigmatic and separated from a radiation beam which is directed to the radiation-reflecting surface. By the use of this element the number of components of the focussing-error detection system can be minimized and a compact construction of said system can be obtained.