In this paper, an optical fiber Fabry-Perot(F-P) acoustic emission(AE) sensor system for the detection of steel crack
initiation has been investigated. The F-P sensors were fabricated by using quartz diaphragm, glass tube and fiber optic.
And the signal processing circuit was designed by using an intensity demodulation method. The test of steel crack
initiation was simulated by using a pencil lead break experiment. The results indicate that the F-P sensing system can
detect weak AE signals at the frequency between 20 kHz and 1MHz, which could be used to on-line monitor of the steel