Plastic optical fibre forms strain gauge sensor
The optical sensor employs the POF to form a “meander path” sensor array that allows a single fibre to form multiple loops that fit in a confined area. These loops, when strained, will alter the phase of an optical signal injected into the fibre.
A separate reference loop that is not strained surrounds the meander path and is used to compare the reference signal to the strained signal and the difference in phase between the two signals can be converted into the strain measurement. The reference fibre simultaneously provides temperature compensation. Since the sensing array only contains optical fibres, it is immune to EMI and EMC related interference and is completely electrically isolated from the rest of the system.