DEVICE FOR OBTAINING APPROXIMATELY PARALLEL LIGHT BEAM FLUX

摘要

PURPOSE:To obtain approximately parallel light beam flux without using any optical lens by absorbing a light beam almost entirely in the internal wall of a cylinder having opening parts at both ends and increasing the distance between both opening parts sufficiently. CONSTITUTION:The cylinder is formed straight of an opaque material such as metal and plastics and its internal wall is coated for preventing reflection. The length (l) of the cylinder is made much greater than the internal diameter (d) of the cylinder. Consequently, only a light beam approximately parallel to the lengthwise direction of the cylinder in light entering the cylinder from the left end in respective directions is obtained at the right end of the cylinder as the approximately parallel light beam flux. Consequently, the approximately parallel light beam flux is obtained without using any optical lens.