Measurement method of VHF elastic vibrations by optical fiber interferometric sensing

A measurement method is presented for elastic vibration modes with extremely small vibration amplitudes in the very high frequency (VHF) range. The measurement system is an optical fiber interferometric sensor, which detects optical phase modulations caused by the elastic vibrations being tested to give the vibration amplitudes. Extensive use of recent optical fiber technology along with a signal processing technique enables the authors to achieve detailed measurements of vibration amplitudes as small as 0.1 A at frequencies as high as nearly 150 MHz