Interferometric measurement apparatus for wavelength calibration

US6816263B2 · kind B2 · utility

Assignee

• Leica Microsystems Semiconductor GmbH · DE

Inventors

• Ulrich Kaczynski · Bad Nauheim, DE
• Klaus Rinn · Heuchelheim, DE

Key dates

• Filing date: Jul 5, 2002
• Grant date: Nov 9, 2004
• Expiry date: Apr 23, 2023

Classification

• Technology area (CPC G): Physics
• CPC primary: G01J9/0246
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

The present invention concerns an interferometric measurement apparatus for wavelength calibration, having a laser light source (1), a detector (2), and an interferometer (3), the laser light source (1) emitting light of at least one wavelength, the interferometer (3) separating the light of the laser light source (1) into two sub-beams (4, 5)—a reference beam (4) and a measurement beam (5)—and combining the sub-beams (4, 5) again after at least one reflection at one reflection means (6) each, and the path length difference between the reference beam (4) and measurement beam (5) defining a constant wavelength calibration distance. In order to increase the measurement accuracy and reduce measurement errors, the measurement beam distance can be extended, but without causing problems in terms of manufacture, assembly, and/or alignment. The interferometric measurement apparatus according to the present invention is characterized in that at least one additional reflection means (8), which reflects the measurement beam (5) at least largely in the opposite direction, is provided in the beam path of the measurement beam (5).