Optical system for focusing a light beam on to an image plane

Abstract

An optical system for focusing a light beam on to an image plane particularly suited for compensating for manufacturing tolerances associated with laser diodes having variable divergence and astigmatism characteristics. The system comprises a collimation lens for collimating the light beam so as to produce a collimated beam in a first plane and an optical shaper having an axis perpendicular to the first plane for correcting distortions associated with the collimated beam and spatially displaced from the collimation lens so as to form the collimated beam on to the image plane. Preferably, the optical shaper includes a pair of cylindrical lenses separated from each other a predetermined distance so as to minimize astigmatism and divergence of the beam. In use, the optical system is adjusted by displacing the collimating lens from the light source so as to produce a collimated beam of light, adjusting the distance between the cylindrical lenses so as to derive a shaped beam having minimal astigmatism and divergence, and adjusting the distance between the collimating lens and the optical shaper so as to focus the shaped beam on to the image plane.