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:
Jul. 26, 1977
Filed:
Oct. 15, 1975
Horst Schmidt, Nauborn, DT;
Knut Heitmann, Wetzlar, DT;
Eckart Schneider, Wetzlar, DT;
Walter Mandler, Midland, CA;
Ernst Leitz Wetzlar GmbH, Wetzlar, DT;
Abstract
Apparatus for the photoelectrical determination of the position of at least one focusing plane of an image comprising an imaging optics, at least one spatial frequency filter in the form of a structure or grating mounted in the vicinity of one image plane of said imaging optics, a photoelectric receiver system associated with the filter containing at least one detector and receiving light fluxes leaving this filter, at least one means for generating a relative motion between the structure or grating and the object image, and means for analyzing the output signals from the photoelectric receiver system for distance display and/or focusing of the apparatus. The apparatus is improved by having the imaging optics (10) preceded by wo rhombic prisms (19, 20) so that each pupil half obtains its light through one of the two prisms. A reference beam is provided to show and/or eliminate mechanical changes in the apparatus effecting faultiness of the measuring result.