METHOD AND INSTRUMENT FOR DISTRIBUTION TYPE PHYSICAL QUANTITY MEASUREMENT

摘要

PROBLEM TO BE SOLVED: To provide a method and an instrument for distribution type physical quantity measurement which is capable of two-dimensional and three-dimensional sensing and easy to recover from an accident, and has high reliability and simple constitution. SOLUTION: For the distribution type physical quantity measuring method which uses an exciting light source 401 emitting light of wide-band wavelength and an optical fiber having sensing zones allocated by wavelengths of light, a sensing optical fiber 421 having the sensing zones processed by FBG is used and has one end of this sensing optical fiber made open into a reflection type and the reflection end connected to an add-and-drop filter 411 having an add-and-drop function. Add-and-drop filters as many as the sensing zones are connected in stages by an optical fiber 400 for a trunk line and a wavelength-independent splitter 402 is connected to the trunk line optical fiber of the initial stage; and the wide-band wavelength exciting light from the exciting light source 401 is guided to the trunk line optical fibers of the initial stage and trailing stages and the signal light which is reflected by the respective sensing optical fibers and returns from the trunk line optical fiber of the initial stage is guided to a wavelength separating filter 404.