Re: [ATM] testing flats with a green laser

[Dominic-Luc Webb <dlwebb@canit.se>]

On Mon, 3 Dec 2007 Hugues.Laroche@ses-astra.com wrote:

> Also, I never saw "frosted" lenses, who would one be interested in such a
> thing, so I guess it's hard to find?

I think I understood the rig used. Really simple actually. It looks
like the usual setup with one flat on top of another. As for the
frosted lenses, they are quite easy to find if you know where to look.
They can be found on some eyeglasses, an assortment of car lights, on
halogen lamps, stage lamps and many other places. The application is
pretty consistent. It is to diffuse light, and I am sure that was
the purpose here. In some cases, the lens may be specified as 1/2 or
2/3 frosted. In the present case, I think the original poster stated
the lens was a blank and was effectively "frosted" only because it
had never been worked.

For clarity, it would be helpful to get some sense of the prescription
of the lens used since this was needed presumably to spread the laser
beam over a sufficiently large area to illuminate the test surfaces.
Laser pointer pens normally have a very bright beam, but they are
intended to have a very narrow beam, so I am guessing that while
this lens was a blank, it had some kind of curve.

Dominic

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