Electro-optic coherent light detector

US5245408A · kind A · utility

Assignee

• The United States of America, as represented by the Director, National Security Agency · US

Inventor

• Jonathan D. Cohen · Tel Aviv-Yafo, IL

Key dates

• Filing date: Jan 11, 1991
• Grant date: Sep 14, 1993
• Expiry date: Jan 11, 2011

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N2201/067
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

An apparatus is described which detects the presence or absence of coherent light and provides an estimate of the coherent light's wavelength. The apparatus employs a common-path "polarization interferometer" in which the two linear polarization paths act as interferometer legs. Electro-optic modulation is used to effect periodic differential path length changes in the interferometer. The apparatus performs synchronous time-integrating detection on the light emerging from the interferometer to measure coherent contributions in the presence of obscuring incoherent light.