The use of laser scanning technology for perimeter protection

The Police Scientific Branch (PSDB) is part of the Crime Reduction and Community Safety Group (CRCSG) of the Home Office. Part of PSDB's work includes evaluating and assessing new technologies for perimeter intrusion detection. Laser scanning technology has been used for some time in a range of industrial and commercial applications. These span from detecting hands when they are close to dangerous machinery to preventing collisions at container ports and monitoring manufacturing processes. Laser scanners are noncontact measurement systems and scan their surroundings two-dimensionally. This paper describes the application of laser scanning to physical security, including modifications to such systems for their use as perimeter intrusion detection systems (PIDS). In these systems, motion detection is provided by a pulsed laser beam by measuring the propagation time for the reflected beam to return to its source. Using this information, a contour plot of the surrounding area is built up. Once this contour information has been obtained, the detector can recognise the addition of an object to its field of view through a change in the programmed surroundings. Consequently, the size, shape and direction of targets moving in the frame can be assessed and an alarm output given if this is required. This paper explains the main operating principles of the systems, including mechanisms for the detection of a potential intruder and the handling of false alarms. Detection capabilities and the potential for low false alarm rates are described, along with configurations for operational deployment.