Active Photoelectric IR Beam detector.
This alarm systems based on PIR detectors will detect intruders.
The curtain is composed of several active IR beam detectors, which create an invisible "grill" inside the window or door bay. Tampering with this area causes an immediate alarm.
These devices can be also used to protect controlled crossings, gates, fances, precious objects in open areas, etc. In museums they can be successfully used to provide conflict-free, discreet separation between the viewers and the valuable exhibits.
During the constant interruption of the beam (by placing an obstacle between the transmitter and receiver), the barrier does not return to its original state. This behavior of the barrier is important for control gates, ramps, etc.