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.

An electronic seal for a casing records the time of changes in the seal state. A sealing strip is fixed in the casing and is formed as a safety loop. A monitoring device is located in the casing and attached to the sealing strip. The monitoring device generates time values which are recorded when changes in the seal state occur.

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).

The present invention relates to a wallpaper which comprises an optical fibre which together with an outside control and/or alarm unit forms a closed optical circuit. The wallpaper is a sheet made from a suitable material, e.g. paper, plastic material and textile fabrics. This material may have the adhesive layer on itself. Alternatively, the adhesive is applied before lamination. The invention relates also to a process for the manufacture of the wallpaper.

A rectangular sheet of backing material has a first surface and a second surface and a conductive wire which is mechanically coupled to the first surface of the rectangular sheet of backing material. A work of art includes a decorative frame and a stretcher frame which has a first surface and a second surface and which has a rim disposed on its first surface along its peripheral edge and a painting canvas which has a front side and a back side. The stretcher frame includes a plurality of individual frame members which permit each of four peripheral edges of the front side of the painting canvas to be folded over so that the folded over peripheral edge is adjacent to the back side of the painting canvas. The dimensions of the stretcher frame may be expanded in order to stretch the painting canvas. The stretcher frame and the painting canvas are mounted on the decorative frame. A plurality of staples secure the conductive wire to the painting canvas, the stretcher frame and the decorative frame. The second surface of the rectangular sheet of backing material is disposed adjacent to the back side of the painting canvas. The conductive wire is electrically coupled to an alarm transmitter and a tamper switch which are disposed within the decorative frame.