Patent · US Expired

Method of determining local structures in optical crystals

US6989904B2 · kind B2 · utility

0Cited by

8References

19Claims

0Family size

Assignee

Schott AG · DE

Inventors

Ewald Moersen · Mainz, DE
Axel Engel · Ingelheim am Rhein, DE
Christian Lemke · Karlsruhe, DE
Guenter Grabosch · Mainz, DE

Key dates

Filing date	Jun 18, 2003
Grant date	Jan 24, 2006
Priority date	—
Expiry date	Jun 21, 2024

Classification

Technology area (CPC G)Physics
CPC primaryG01N21/958
WIPO fieldMeasurement
WIPO sectorInstruments

Abstract

The method for determining local structures in optical materials, especially crystals, includes observing schlieren visually in a material to be tested with divergent white light in a first step; measuring birefringence of polarized laser light in the material to determine local defects and structure faults in the material with a spatial resolution of 0.5 mm or better in a second step if the material is judged to be suitable in the first step and then interferometrically measuring the material to determine the faults in the material by interferometry in a third step if the material is judged to be suitable in the first and second steps. This method can be part of a method for making optical components, especially for microlithography.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.