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:
Dec. 12, 1988
Ernst Brinkmeyer, Buchholz, DE;
U.S. Philips Corp., New York, NY (US);
Abstract
An optical backscattering meter includes an optical transmitter whose transmission power is modulated (wobbled) with a variable frequency via an oscillator and whose transmission beam is coupled into a light wave cable (LWL) via a beam splitter. It further includes an optical receiver including an avalanche photodiode, to which receiver are applied, via the beam splitter, portions of the transmission beam that are scattered back from the light wave cable (LWL). A mixing signal is formed from a signal proportional to the optical backscattering power and a modulation voltage having the oscillator frequency and is evaluated for determining the location of the backscattering and the intensity thereof. The cost of the optical receiver is reduced by the use of the avalanche photodiode (4), whose bias voltage is a d.c. voltage (U.sub.G) modulated by the modulation voltage (U.sub.M), and because the mixing signal (U.sub.P) can be tapped at a parallel circuit comprising an ohmic resistor R.sub.P) and a capacitor (C.sub.P) inserted in the energizing circuit of the photodiode.