Apparatus for determining the relative position of the plane of maximum amplitude of the local frequency component

US3953728A · kind A · utility

Assignee

• Ernst Leitz GmbH

Inventors

• Ludwig Leitz
• Werner Holle · Wetzlar, DE
• Knut Heitmann · Wetzlar, DE

Key dates

• Filing date: Oct 24, 1974
• Grant date: Apr 27, 1976
• Expiry date: Oct 24, 1994

Classification

• Technology area (CPC G): Physics
• CPC primary: G02B7/365
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

In an apparatus, an imaging system, at least one optically effective grating and a photoelectric receiver system are employed for determining the relative position of the plane of maximum amplitude of a spatial frequency component in the image of an object. The imaging system produces from light fluxes emanating from the object and traversing different regions of the entrance pupil of the imaging system an image of the object in a first, a second and a third intermediate image plane. The focussing screen mounted in the first plane is used for subjectively observing and focussing the object as well as for transmitting light fluxes to the optically effective grating which defines a given spatial frequency component and which is mounted at least in the vicinity of the second intermediate image plane for commonly modulating and splitting the light fluxes. The photoelectric receiver system generates therefrom electrical output signals used in devices for indicating and adjusting the sharp focussing of the object.