I like this solution - the power loss is minimal (only the side lobes are cut off) and the complementary lenses convert all incoming power to outgoing power (less the lenses' reflection and absorption losses).
Simple, elegant, effective. Who needs more?
Donald.
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----- Original Message -----
> From: "Boman33" <boman33@...>
> To: "Homebrew PCBs" <Homebrew_PCBs@yahoogroups.com>
> Sent: Tuesday, March 8, 2011 6:32:47 PM
> Subject: RE: [Homebrew_PCBs] Re: Laser Photoplotter
>
> Here is some additional info for cleaning up a laser beam:
>
> Changing the shape factor can also be done with a front surface mirror
> at an angle. Vary the angle until the shape is correct.
>
> Typically a laser has side modes or spots. Shine it on a white wall
> and the extra ones can be seen. To clean them up use a microscope
> objective focusing the beam on a really small pin hole. On the other side there
> is another objective also focused on the same pinhole and the output is
> a parallel cleaned up laser beam. This assembly must be very stable and
> also adjustable to focus & align the components.
>
> Bertho
>
[snip]