RESUMO
The design of a noncontact fiber-optic sensor is described for the detection of acoustic emission for structural integrity monitoring in high-temperature power plant applications. The sensor is based on a Sagnac interferometer and produces an output proportional to target velocity, without the need for active phase stabilization. It is inherently insensitive to low-frequency perturbations of the instrument or the target and incorporates an environmentally insensitive downlead, which may be of arbitrary length. It is shown that the sensor is capable of meeting the specifications for structural integrity monitoring of high-temperature power plant components based on acoustic emission detection and has a velocity resolution of 50 nm s(-1) Hz(-1/2).
RESUMO
Optical fiber interferometry was used for measurement of the subnanometer surface and bulk displacements associated with photoacoustic pressure waves in methanol and water. The measurement system is both broadband and noncontacting, giving a pressure sensitivity of 0.1 Pa/ radicalHz.
