<title>Laser beam width, divergence, and propagation factor: status and experience with the draft standard</title>

Abstract

Laser beam width, divergence, and propagation factor are three major parameters required to apply a source. This paper discusses the status of the draft standard ISO TC172/SC9/WG 1. The two methods, free beam and lens method, are described and experimentally shown to give near equal results for a single TEMoo source. For nearly collimated sources, a quick method requiring two beam widths is described to give the key parameters. Basic measurement devices including slit scan, pinhole scan, encircled energy, knife edge scan and their array equivalents are described. These methods are compared to the theoretical variance beam measurement device with the result that the slit scan produces the least inherent error, 0 to 4% for the first six laser modes, assuming zero slit width.