Autofocus device and autofocusing method for an imaging device

US9229209B2 · kind B2 · utility

Assignee

• Carl Zeiss SMT GmbH · DE

Inventors

• Michael Arnz · Oberkochen, DE
• Mikhail Levtonov · Landshut, DE
• Gerd Klose · Hamburg, DE
• Volkmar Betz · Jena, DE

Key dates

• Filing date: Jan 20, 2009
• Grant date: Jan 5, 2016
• Expiry date: Mar 7, 2029

Classification

• Technology area (CPC G): Physics
• CPC primary: G02B21/245
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

An autofocus device for an imaging device is provided, which has an imaging optic having a first focal plane and an object table for moving an object to be imaged relative to the first focal plane, wherein said autofocus device comprises a) an image recording module having a second focal plane, the location thereof relative to the first focal plane being known, b) a lighting module (BM) for imaging a focusing image along a lighting beam path in a focusing image plane such that, if the object is positioned in a target position at a predetermined distance to the second focal plane, the lighting beam path is folded because of reflection on the object and the focusing image, which lies in the focusing image plane, intersects the second focal plane or lies therein, and c) a control module, which activates the object table to focus the imaging device so that the object is positioned in the target position, from a signal of the image recording module, which the image recording module generates on the basis of the recording thereof of the focusing image when the object is positioned in the target position, derives the deviation of the object position from the target position, and, based on…