Optical feedback isolator

US4844593A · kind A · utility

Assignee

• Hewlett-Packard Company, L.P. · US

Inventors

• David Parker · Preston, GB
• John H. Gliever · San Jose, US

Key dates

• Filing date: May 16, 1988
• Grant date: Jul 4, 1989
• Expiry date: May 16, 2008

Classification

• Technology area (CPC G): Physics
• CPC primary: G01J2009/0261
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

Method and apparatus for isolating optical feedback in a laser interferometer having a laser light source from which a linear polarized outgoing laser beam of certain polarization orientation is derived. The interferometer also redirects the outgoing laser beam to form a return laser beam directed to a receiver. The outgoing laser beam and the return laser beam are physically close and are substantially parallel. The linearly polarized outgoing laser beam is converted to circular polarization. A portion of the circularly polarized return laser beam directed toward the laser light source is converted back to linear polarization with polarization orientation orthogonal to the polarization orientation of the outgoing laser beam. A portion of the circularly polarized return laser beam directed toward the receiver is converted back to linear polarization with polarization orientation being substantially the same as the polarization orientation of the outgoing laser beam. The portion of the return laser beam with polarization orientation orthogonal to the polarization orientation of the outgoing laser beam is directed away from the laser light source, and the portion of the return laser …