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Subject: RE: [Homebrew_PCBs] RE: 10W ~380nm UV LED for exposing Riston & other negative film photoresists

From: "Boman33" <boman33@...>
Date: 2013-11-19

I understand about lost power.   In my example the beam was round to start with but I had to filter out secondary beams to provide an as clean beam as possible and I was not looking for max power.

 

My point was exactly that:  The beam expander + big aperture would be similar to a small aperture and no beam expander: both would lose significant power.

 

To preserve power as discussed, use either a curved mirror in one dimension or a cylindrical lens.

Bertho

 

From: Slavko Kocjancic   Sent: Tuesday, November 19, 2013 03:59

On 11/19/2013 09:39 AM, Boman33 wrote:

Note, my example had nothing to do with obtaining a small spot for developing artwork or PCBs.  It is a common method for obtaining a “clean” laser beam focused on infinity.  It was used for optical experiments.  A beam expander will not remove any secondary laser beams, they too will be expanded.

A beam expander plus an aperture presumably will be the same as just an aperture of a smaller size directly in the beam.  For example, if the laser beam is 1 x 3mm, a 1mm aperture would give a 1mm beam.  Would that not be identical to a 10X beam expander with a 10mm aperture?

Bertho

Doesn't matter.
If beam is 1x3mm and I need 1x1mm with this method I lost 2/3 of power. It's only masking unwanted portition. And expanding and companding losse some power too. I just wonder if I can remove that with lens (colimator) tilted. Or some additional lens tilted...  ...need to try, but for now I'm focused ti try the LED aproach