The reflection value of the fiber optic sensor decreases
A variation of the period of the grating inscripted in a fiber optic – induced by mechanical or thermal perturbation – causes a shift of the reflected peak wavelength, due to the related optical path length variation. Reflectance (which has also been called "back reflection" or optical return loss) of a connection is the amount of light that is reflected back up the fiber toward the source by light reflections off the interface of the polished end surface of the mated connectors and air. This is always measured in dB (decibels) and will be displayed as a negative number. Radiation absorption creates electronic excited states that are trapped by localized defects for extended periods of time. This makes it highly reliable even under severe environmental conditions, such as temperature, vibration, shock, water, and electrical noise conditions. The total reflected power can be due to connector back reflections, back scattering, etc.
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