Method and arrangement for determining an at least approximately circular contacting surface using incoherent light and a film waveguide

US5440140A · kind A · utility

Assignee

• JENOPTIK GmbH · DE

Inventors

• Steffen Goerlich · Jena, DE
• Wolfgang Merker · Jena, DE
• Peter Voigt · Hallbergmoos, DE
• Norbert KLOSE · Graitschen, DE
• Klaus Moehr · Eisenberg, DE
• Joachim Wieser · Jena, DE

Key dates

• Filing date: Apr 4, 1994
• Grant date: Aug 8, 1995
• Expiry date: Apr 4, 2014

Classification

• Technology area (CPC G): Physics
• CPC primary: G01B11/285
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A method and arrangements for determining an at least approximately circular contacting surface is disclosed. The primary object of finding a simple way of objectively determining the contacting surface of a deformable medium on a plane surface with high accuracy and at a low technical expense is met according to the invention in that a film waveguide is used as a plane surface. An incoherent, parallel, homogeneous bundle of light whose width widens one-dimensionally is coupled into this film waveguide and the decoupled light is fed to a photoreceiver array for recording one-dimensional intensity distributions. An evaluating unit generates a difference curve from a normal curve without contacting medium and from a measurement curve with contacting medium and the exact diameter of the contacting surface is determined from the distance of two associated extremes of the difference curve. The method and arrangements are preferably used in ophthalmology for the measurement of the applanation circle at the tonometer and for measuring liquid drops for the purpose of analysis.