Method and apparatus for analysis of schlieren

US6891980B2 · kind B2 · utility

Assignees

• Schott Glas · DE
• Carl Zeiss SMT GmbH · DE

Inventors

• Michael Gerhard · Aalen, DE
• Frank-Thomas Lentes · Bingen, DE
• Christian Kusch · Jena, DE
• Wolfgang Singer · Aalen, DE
• Ewald Moersen · Mainz, DE

Key dates

• Filing date: Mar 5, 2002
• Grant date: May 10, 2005
• Expiry date: Nov 3, 2023

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N21/958
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

The method for evaluating schlieren in glassy or crystalline optical materials includes irradiating a test sample of the optical material with light and producing a shadow image of the test sample on a projection screen. The shadow image of the test sample is received in an electronic image receiving device, such as a digital camera, and is compared with another shadow image of schlieren obtained with a comparison sample by means of interferometry. Then the optical material of the test sample is evaluated with the help of the comparison results.