Browsing by Author "Po-Wen"

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Method of enhancing spatial resolution for distributed temperature measurement
(2004-11-16)
Chi
;
Sien
;
Lee
;
Chien-Chung
;
Chiang
A method that utilizes a short sampling interval and a long-pulsewidth laser source to obtain the long sensing range and employs a signal processing technique of decomposing Brillouin spectrum to achieve high spatial resolution, high temperature resolution of the distributed temperature measurement is disclosed. The present method includes the steps of measuring the Brillouin spectra of an optical pulse applying to a sensing fiber and a overlapped area thereof, determining the length that the pulse enters according to the measured Brillouin spectra and a weighting factor and then determining a real Brillouin spectrum profile and a temperature distribution according to Brillouin frequency shifts thereof. For a 9500-m sensing range of standard single-mode fiber and a 100-ns pulsewidth laser source, spatial and positon resolutions of 20 cm and a temperature resolution of 1.degree. C. are simultaneously achieved by using this signal processing method.
Method of utilizing a fiber for simultaneously measuring distributed strain and temperature
(2004-03-02)
Chi
;
Sien
;
Lee
;
Chien-Chung
;
Chiang
A method that utilizes a dispersion-shifted fiber having compound compositions with different temperature coefficients in core to simultaneously measure the distributed strain and temperature based on Brillouin frequency shift is disclosed. The present method includes the steps of obtaining mean two peak frequencies in a multi-peak Brillouin spectrum of the dispersion-shifted fiber, determining a temperature change according to the formula of a Brillouin frequency shift of the peak relating to strain and temperature conditions of the fiber, and determining a strain change through the formula. In a 3682-m sensing length of Large-Effective-Area NZ-DS fiber, a temperature resolution of 5.degree. C., a strain resolution of 60 .mu..epsilon. and a spatial resolution of 2 m are achieve simultaneously.