[Laser] Cheap 8x11 Lens

[Karel Kulhavy]

> 
> I taped one of these Fresnel lenses to a sheet of glass (at the corners) 
> for extra rigidity.  You could probably also use an acrylic sheet, which
> would be less fragile if you're bouncing it around in a car like I do.  :)

I have done it also this way and it is loosening in the middle. Best is to
compress it between two glasses. You get only 1dB loss on the second glass and
the lens is much more rigid then.

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