Abstract: An orthogonal light plane generator is associated with a primary light plane generator to convert a portion of a first light plane projected by the primary light plane generator into a second light plane substantially orthogonal to the first light plane. The orthogonal light plane generator comprises a diverter which defines three or more reflecting surfaces for receiving a portion of the first light plane and redirecting that portion as the second light plane. The three or more reflective surfaces are oriented relative to one another such that tilting of the orthogonal light plane generator is compensated to maintain the orthogonality between the two light planes. Tilting about one axis results in offset of the second light plane and tilting about a second axis orthogonal to the first results in a shifting of the sector within which the second light plane is projected, but tilting about either axis does not affect the orthogonality between the planes.