Optical barrier is constructed as well as monitoring device

摘要

A surveillance device is composed of several optical barriers (2) and has several patterned fields (4) arranged at one end of a surveillance zone (B), objectives (6) at the other end of the surveillance zone (B) and associated to the patterned fields (4), and reflectors which deflect image beams supplied by the objectives onto a reproduction surface. A sensor (8) upon which the objectives (6) reproduce the image of the patterned field (4) scans the image and transmits corresponding signals to an evaluation device (10) which determines if the image received by the sensor (8) has the same optical characteristics as the patterned fields (4).