Our latest paper, published in the IOP journal Measurement science and technology (http://iopscience.iop.org/0957-0233/) , describes a novel optical signal processing scheme for range-resolved interferometric processing. The scheme originally investigated for applications in LIDAR is applied to a form of optical fibre sensors - Fibre segment interferometry (FSI) – that has the potential to offer very economical, long-gauge length sensors, for the measurement of strain and temperature. In fibre segment interferometry (FSI), consecutive segments of fibre are separated by weakly back reflecting nodes that act as interferometric signal sources. The phase signals from two neighbouring reflectors can be subtracted, resulting in a measurement of the optical path difference (OPD) integrated over the whole length of the fibre segment between the reflectors. In this paper a signal processing scheme that uses code-division multiplexing to separate signal sources and single-sideband (SSB) homodyne signal processing to recover the interferometric phase. The combination of CDM with SSB homodyne signal processing, allows both multiplexing and signal processing to be performed using only a single standard phase modulator with a simple continuous-wave, single-frequency laser diode.
The full paper will be available soon from Measurement science and technology (http://iopscience.iop.org/0957-0233/):
Fibre segment interferometry using code-division multiplexed optical signal processing for strain sensing applications
Thomas Kissinger, Thomas O H Charrett and Ralph P Tatam
Measurement Science and Technology, Vol. 24, p094011 (http://iopscience.iop.org/0957-0233/24/9/094011)
Or via CERES https://dspace.lib.cranfield.ac.uk/ (Cranfield University institutional repository).