Abstract: A composite security panel having at least two fibre optic elements contained within a block of material, the elements being arranged with portions emerging from the panel at three or more spaced locations. Translatory movement, rotation or tilting of the panel when assembled in a wall or housing causing translatory movement of an emergent portion of an element resulting in the interruption of a transmission line through the wall of housing. The elements may be firmly embedded within the panel, the fibre optic being carried on a strip of mateial, or the elements may be formed into a mesh which can be loosely housed between interconnectable sections of the panels.

Abstract: A security system having a mesh-like intruder detection structure for use as or with a security fence 2 or for detecting intruders jumping down from a fence or wall. The structure is made up from a number of elongated members (4, 6, 8, 10, 12, 14) each in the form of or including a fibre-optic waveguide, the elongated members being secured together at a number of spaced jointing points (20) spaced 20 cms or less apart. Portions of the elongated members at the jointing points are held in a position fixed relative to one another by encapsulating the jointing points in a plastics material (40), welding the portions together and/or surrounding them with a metal ferrule (38).