PMG
Light Pipes and Homogenizers.

Light Pipes and Light Guides
Light pipes, often called light guides, direct light from a source to where it is needed.

Homogenizers
Light homogenizers are optical components that make light beams more uniform by eliminating variations in intensity and smoothing the beam's overall envelope. This results in more consistent light over a specific area. Homogenizers often have 4, 6, or 8 long edges to assist with this action.