<title>Optics for vector scanning</title>

Abstract

Vector scanning of laser beams is critical to the success of stereolithography, laser marking, CAD-output-to-microfilm and many other industrial applications. The design of a vector scan lens system can assume many different configurations. This paper will discuss pre-objective, and post-objective alternatives for two and three axis scanning. Various parameters required for system specification are reviewed and the basic configuration of the two axis scan head is presented. The pre-objective scan f-theta lens, its scan distortion, telecentric options, and single origin scan systems are described. Fixed focus and dynamic focus post-objective systems are presented discussing the relative merits of each approach and noting the limitations of each design solution. Data presented describe limiting field sizes for fixed focus systems, and limiting f-numbers for thin lens systems. Thin lens design equations for three post-objective configurations are presented with suggested optimization techniques for overall system layout. Examples of pre-objective and post-objective scan lens systems as well as pre- configured systems are presented.