第一種 vibration sensor
The sensor is made of a quartz crystal placed a submicron distance from the surface of an optical fiber with a 55° cut. This arrangement is chosen so that light leaving the fiber is close to being totally internally reflected. When the light leaves the fiber, it rates the quartz crystal due to frustrated total internal reflection. When the quartz crystal vibrates, the gap between the crystal and the fiber changes. When the gap changes, the amount of radiation power passed to the crystal changes.
With total internal reflection, some radiation rates the medium with a lower index of refraction. Radiation propagates in the second adjacent medium if it is close to the first pared to the ration depth.
第二種 vibration sensor
A coil with a core made of ically soft material and a permanent are mounted on the housing of a body susceptible to vibrations. The output signal is detected across a resistor coupled to the coil. The output signal is delayed with respect to the input signal applied to the coil. The time delay is equal to the saturation time of the ically soft material. This time in turn depends on the flux of external ic field that acts on the ically soft material.