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. 04, 1990
Filed:
Nov. 12, 1987
British Telecommunications public limited company, London, GB;
Abstract
A method and apparatus for locking the frequencies of a number of first beams of coherent radiation from respective sources. Typically, the sources will form local oscillators in respective transmitters. The apparatus includes a reference beam generator such as a HeNe laser which generates a primary reference beam fed to an interferometer which generates a second, reference beam composed of a number of reference frequencies. This second reference beam is caused to interfere with each of the beams from the local sources in an optical coupler and the resultant beam is detected with a photodiode. The electrical output signal of the photodiode is filtered and fed to a discriminator which controls the frequency of the local laser. The discriminator controls the laser to maintain the relationship between the frequencies of the laser and the reference laser substantially constant.