Optical collimators and RECI beam divergence

[medicdude]

Does anyone know the beam divergence of the RECI tubes?

There are 'beam expanders' for sale, but they do not appear to allow modification of lens spacing, it would be nice if they did, or if there was a collimating frame available for putting lenses into.

A properly positioned collimator can greatly 'smooth' the power difference seen on large tables, which is due to beam divergence (beam getting wider the further you go from the tube). There's a neat Java applet here you can experiment with to see the effects of collimators (Model p100 seems to be closest to RECI tube): http://www.synrad.com/Applications/BeamTool/launch.html

You can also use the collimator to widen the beam, letting you get the smallest spot size for speed engraving, or for cutting metals.

Some more info (and math) about collimators here: http://www.newport.com/Focusing-and-Col ... ntent.aspx