Distributed measurement of static stain in an optical fiber with multiple Bragg gratings at nominally equal wavelengths

摘要

The Fourier transform relationship between the reflected light from a Bragg grating and the complex spatial modulation of the Bragg grating is used to produce a distributed strain sensing system. A tunable external cavity diode laser along with a reference reflector in an optical fiber are used to produce a measurement of the phase and amplitude of the reflected light from the modulated Bragg grating as a function of wavelength. The system is demonstrated with 22 Bragg gratings in a single fiber on a cantilever beam and compared with foil strain gauge readings. OCIS codes: 230.1480, 050.2770, 060.2370, 060.2430, 060.2300.