Process and apparatus for the automatic focusing of microscopes

US4958920A · kind A · utility

Assignee

• Carl Zeiss Stiftung · DE

Inventors

• Reinhard Jorgens · Aalen, DE
• Bernd Faltermeier · Aalen, DE

Key dates

• Filing date: Aug 18, 1989
• Grant date: Sep 25, 1990
• Expiry date: Aug 18, 2009

Classification

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

Abstract

Fast and versatile autofocusing for microscopes is achieved by the interaction of two known systems: a first, active autofocusing system (12) which projects at least one light dot on the object and develops a focusing signal dependent upon the character of a reflection of the dot; and a second, passive autofocusing system which creates a video signal representative of an image of the object and then uses the image contrast of that video signal as a focusing criterion. Provided for both systems is a joint control unit (45) to which the signals (g), (f) of both focusing systems are transmitted and which, successively, activates first the active and then the passive autofocusing system. The process can be used to focus on both covered and uncovered objects illuminated by transmitted as well as reflected light. Quick, automatic focusing is accomplished in that the active focusing system rapidly focuses first on either the cover glass surface or the object surface and then control is switched to the passive autofocusing system which only needs to travel a very short distance to achieve accurate final focus of a preselected plane of the object.