| 摘要 |
A method and apparatus are disclosed for sensing acoustic signals emitted from materials and structures. The method includes the steps of embedding or surface mounting a fibre-optic mode-coupling element (4) having a light input end (3) and first and second light output ends (5, 7) in or on a said material or structure from which an acoustic emission signal is to be sensed; providing a narrow band-width light source (1) optically linked to the input end of said mode-coupling element; providing a detector (8, 9) for detecting light emanating from said mode-coupling element for converting light output from each end into first and second output electrical signals; and providing a comparator for comparing steady state output electrical signals with output electrical signals following an acoustic event sufficient to modulate the mode-coupling coefficients between the output fibres in the mode-coupling element. Various embodiments of sensing apparatus are also described for performing the method of the invention. |
