An economical and multiple fibre grating sensor system with a rapid response using code division multiple access

The performance of the ordinary fibre Bragg grating sensor strain measurement system, which uses a Fabry-Perot filter for scanning wavelength, has limitations in application due to the hysteresis characteristics of the PZT element in the filter, the slow scanning rate of the filter and the high cost of the system. The system proposed here uses a LED as a light source and adapts the method of code division multiple access (CDMA). Without a tunable laser source or Fabry-Perot filter, the price of the system is very low and the speed of response of the system is very fast. CDMA is based on correlation techniques implemented in order to separate out individual reflected sensor signals from a multiplexed signal.