Laser Technologies for Unattended Remote Monitoring

There are situations where visual surveillance proves ineffective in detecting changes occurring in a specific environment, caused either by moving objects or people, or by modifications made to the environment itself. Changes may be too small to be reliably detected or spurious alarms may be generated caused by illumination changes. Further, illumination blackouts, whether by accident or on purpose, prevent cameras from their surveillance function. High security installations need reliable, independent and effective sensors capable of keeping the surveillance work even during a blackout. The paper describes different examples of laser surveillance systems (i.e., contactless, self-illuminated, line-of-sight, distance measurement instruments) and proposes their use for supplementing conventional surveillance means (e.g., cameras). These integrated sensors combine the advantages of visual surveillance and overcome the problems described above, making them particularly suited to unattended remote monitoring applications. In addition, laser surveillance provides a direct measurement of the exact position and dimension of changes. Different instruments and applications will be discussed, namely, 2D and 3D surveillance, and a few prototypes described.