The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 18, 1990
Filed:
Sep. 08, 1989
Lauren M Peterson, Ann Arbor, MI (US);
Environmental Research Institute of Michigan, Ann Arbor, MI (US);
Abstract
The present invention detects the difference in phase between the modulation of a received optical beam and a reference RF signal or a second modulated optical beam. The received optical beam is modulated by the reference signal and by this reference signal phase shifted 90 degrees. The difference cross modulation in these two modulated optical beams is detected. The phase difference to be detected is formed by dividing the difference cross modulation of the modulated second optical beam by the difference cross modulation of the modulated first optical beam. This quotient is proportional to the tangent of the phase difference to be detected. The optical modulation can be achieved by bulk electro-optic modulators operating on split beams, by a bulk electro-optic modulator alternatively modulating a single beam by the reference signal and the phase shifted version of the reference signal, or by changing the coupling between two parallel, matched wave guides in an integrated optic device. This system is useful in elimination of amplitude-phase cross talk in phase shift modulation optical communications systems and in three dimensional optical ranging systems.