Patent ID: 8089614

Claim:
A device for changing a pitch between light beam axes to reduce a pitch Px of parallel light beams emitted from light sources to another desired pitch Px′ in an x direction on which are arranged in the x direction and y direction in a shifted manner in the y direction, comprising: a first transparent member in the shape of a prism whose cross section in the x-z direction is a parallelogram and whose height perpendicular to the cross section is higher than the sum of the distance in the y direction between the most distant light sources and the diameter of said parallel light beam; and second transparent members, the number of which is one less than the number in the x direction of said light sources, in the shape of a prism, wherein each of the second transparent members has a cross section in the x-z direction that is a similar parallelogram to that of the first transparent member with the same interior angles, a side in the x direction that is Px-Px′ in length and a height perpendicular to the cross section that is higher than the sum of the distance in the y direction between the most distance light sources and the diameter of said parallel light beam, each of the second transparent members including the same number of grooves as the number in the y direction of said light sources formed in an oblique surface of each of the second transparent members which is the surface corresponding to the side adjacent to said side of Px-Px′ in length, the first transparent member and the second transparent members being stacked so that said oblique surface of one of the second transparent members is in direct contact with the oblique surface of the first transparent member and the surface corresponding to said side of Px-Px′ in length of the second transparent members lies in one plane with the surface adjacent to said oblique surface of the first transparent member, wherein light trying to enter one of the grooves undergoes total reflection by the one groove.