Optical beam collimation procedures and collimation testing: a summary

Abstract. A collimated optical beam is required in several applications such as metrology, optical processing, free space propagation of information, and laser-based instrumentation. Prior to the advent of the laser, the size of the aperture at the focal point of a collimating lens determined the degree of collimation based purely on geometrical optics consideration. Because the laser beam can be focused to a tiny size, effectively making it a point source, the degree of collimation is governed by diffraction at the aperture of a collimating lens. A large number of procedures have been developed to collimate the beam. We examine the development of these techniques from the historical perspective.