Abstract: The invention relates to a reflective light barrier, with an optical transmitter (3) and an optical receiver (4) positioned on one side of the surveillance area, and a reflector positioned on the other side, which reflector modifies the polarization of the light upon reflection, where at least one optical element (1, 2, 7, 7a, 7b) and one polarizing filter (11, 12) are positioned both between the optical transmitter (3) and the reflector, and between the optical receiver (4) and the reflector, and where the polarization planes (13, 14) of the two polarizing filters (11, 12) intersect each other, such that at least one of the two polarizing filters (11, 12) is extrusion-coated with optically transparent material, either fully and/or on the back, and such that the optically transparent material forms at least one of the optical elements (1, 2, 7, 7a, 7b).

Abstract: A mirror collimator has a larger parabolic mirror (11) and a smaller convexly shaped capture mirror (12) arranged at the concave side of the parabolic mirror and on its optical axis (27). A cut-out 15 is formed at the common focal point of the parabolic mirror (11) and of the capture mirror (12) and a photo-element (16) is arranged in the area of this cut-out (15). The capture mirror (12) is secured to the parabolic mirror (11) by at least one carrying device (17) extending alongside the cut-out (15).