The fiber gap sensor consists of a seismic mass which is held by two pivots inside a housing. The input fiber is bond to the seismic mass, the output fiber to the housing. Both fiber surfaces are adjusted to each other and light can be transmitted over a small gap. An applied acceleration displaces the centers of the fibers to each other and the light intensity is decreased.
Following picture illustrate the working principle of a fiber gap sensor with pivots.
The mechanical complexity of this sensor concept is low. Low cost production technologies are available. One difficulty for the assembly is the adjustment of the fiber and its perpetuation during the bonding process.
the size and weight of this sensor will both be medium
A similarity to cantilever sensors is given which enables the assumption that the linearity and the cross sensitivity can both reach the required values.