Absolute interferometer measuring process and apparatus having a measuring interferometer, control interferometer and tunable laser

US5631736A · kind A · utility

Assignee

• DR. JOHANNES HEIDENHAIN GMBH · DE

Inventors

• Jurgen Thiel · Surberg, DE
• Dieter Michel · Traunstein, DE
• Andreas Franz · Ludwigsburg, DE

Key dates

• Filing date: Mar 12, 1996
• Grant date: May 20, 1997
• Expiry date: Mar 12, 2016

Classification

• Technology area (CPC G): Physics
• CPC primary: G01B2290/60
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

An absolute measuring interferometer having a measuring interferometer, a tunable laser emitting a laser beam and a control interferometer for adjusting the air wavelength of the laser beam. The control interferometer adjusts the air wavelength of the laser beam to a specific wavelength value at the ends of each measuring cycle. The wavelength of the tunable laser is continually tuned within the specific wavelength interval where the phase change of the interference signal is continually detected during the wavelength modulation process. An absolute measurement is determined by a simple mathematical relationship between the measured wavelength and phase changes.