Homebrew PCBs

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

 

From: Cristian   Sent: Tuesday, November 19, 2013 02:42



>To get a as clean beam as possible I have done the opposite to the 
>beam expander:
>
>Using microscope objectives, the beam is focused on a very small pin 
>hole. Any secondary beams or distortions does not get through the 
>pin hole. The beam is collimated afterwards with a matching second
objective.

Your solution is the same as with an expander: the pin hole has to be 
of 0.06mm diameter (the smallest beam dimension) and you will loose 
the same amount from the perpendicular dimension
as in the expander variant.
Try the led version, it is near square, and the laser's coherency is of no
use.
Cristian