Optical apparatus for producing a light curtain

In an optical apparatus for producing a light curtain, a fibre optic rod which is round in cross-section, having a light entry side for receiving light from the curtain area and a circumferential surface opposite said light entry side, said rod comprising a system of adjacent inclined mirrors, arranged one next to the other, said system attached to a narrow zone of the circumferential surface of said rod, running parallel to the axis thereof and said mirrors disposed at an angle to the axis of said rod, such that substantially all of the light entering the rod, normally to the axis thereof, is reflected outwardly thereof at an angle to the rod axis lying below the total reflection critical angle.

An optical apparatus for producing a light curtain, having a light source emitting a collimated beam of light, and a light distribution system, guiding the light beam over the curtain area, comprising a transmitting fiber optic rod having two end faces, one of said end faces receiving at least one light beam entering at an angle to the axis of the rod, means for introducing said light beam at said angle, a system of adjacent inclined mirrors, said mirrors inclined at an angle to the rod axis such that said light beam striking them is deflected towards the curtain area with said system located on the surface of the rod remote from the curtain area, a receiving fibre optic rod, disposed on the same side of the curtain area as the transmitting fiber optic rod, parallel to and beside the latter, and an elongated retro-reflecting region located on the other side of the curtain area, said retro-reflecting region having a scattering range adequate for illumination of the receiving fiber optic rod.