Method for determining the focal position during imaging of a sample using an inclined position receiving device

US7488924B2 · kind B2 · utility

Assignee

• Carl Zeiss Micromanaging GmbH · DE

Inventors

• Daniel Bublitz · Glinde, DE
• Dieter Graefe · Jena, DE
• Peter Westphal · Jena, DE

Key dates

• Filing date: Apr 27, 2004
• Grant date: Feb 10, 2009
• Expiry date: May 17, 2024

Classification

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

Abstract

The invention refers to a process for determining the focus position when imaging a specimen (4) with a field stop imaged onto the specimen detecting this image using a position-sensitive receiving-device inclined relative to the field stop defining the focus position by means of intensity distribution in the receiving device. The invention also refers to set-ups as regards implementation of the process according to the invention.According to the invention, in a process of the above-mentioned type, imaging of the field stop onto the specimen (4) is at least partially superposed by an optical lattice; the position-sensitive receiving device is used to determine intensity values for the light reflected by the specimen; these intensity values are assigned to positions in the receiving device; position-related contrast values are determined from the position-related intensity values; the position of the contrast focus in the receiving device as equivalent of the current focus position is determined using these contrast values.