OPTICAL FIBER TYPE PHYSICAL QUANTITY MEASURING INSTRUMENT

摘要

PURPOSE:To improve the physical quantity measuring accuracy of the title instrument by directly supplying part of incident pulsed light to correlation processing circuits through OTDR measuring systems by using a branch pipe and using the pulse train of incident pulses as a coefficient for processing correlation. CONSTITUTION:Pulsed light emitted from a light source 12 is divided into two parts through a branch pipe 32 and supplied to correlation processing circuits 24a and 24b through the photoreceptors 20a and 20b and averaging circuits 22a and 22b of two OTDR systems. The circuits 24a and 24b find correlation between the pulse trains of Raman scattered light separated into Stokes' light and anti-Stokes' light by means of an optical multiplexer/demultiplexer 18 by using supplied incident optical pulse trains as coefficient trains. An arithmetic circuit 26 measures the temperature distribution in an object to be measured from the intensity ratio between the Stokes' light and anti-Stokes' light.