Dynamic Clearance Measurement Using Fiber-Optic Frequency-Swept and Frequency-Fixed Interferometry

Aiming at the problems of Doppler-induced error and slow measurement rate in frequency-swept interferometry, a novel dynamic clearance measuring method is proposed. By combining frequency-swept and frequency-fixed interferometry, and using fusion processing of interferometric signals, this method not only can eliminate the Doppler-induced error, but also can give the dynamic clearance value at each sampling point. To verify this method, an all fiber-optic measurement system was constructed, and experiments under 500 Hz triangular and 4 kHz sinusoidal vibrations were carried out. Experimental results show that the dynamic clearance can be reconstructed accurately.