Laser Beam Expander - Tutorial and demonstration
The beam expander is an optics designed to be used with lasers to control beam properties such as divergence, length and focus point. This video explains how the beam expander works and gives several examples of the beam expander in action using the Spartan GW 200mW laser. The Beam Expander is from Dragonlasers at http://www.dragonlasers.com