Physical Sciences and Mathematics Commons^™

Programmable Logic Controller Based Fibre Bragg Grating In-Ground Intrusion Detection System, Gary Allwood, Graham Wild, Steven Hinckley

Australian Security and Intelligence Conference

In this paper we present an in-ground intrusion detection system for security applications. Here, an optical fibre pressure switch is directly connected to a standard digital input of a programmable logic controller (PLC). This is achieved using an intensiometric detection system, where a laser diode and Fibre Bragg Grating (FBG) are optically mismatched, resulting in a static dc offset from the transmitted and reflected optical power signals. Pressure applied to the FBG, as the intruder stepped on it, induced a wavelength shift in the FBG. The wavelength shift was then converted into an intensity change as the wavelength of the …