[ATM] testing flats with a green laser
gfbrandenburg at yahoo.com
Mon Dec 3 19:34:40 JST 2007
I guess I was the original poster.
The 'frosted' lenses we used are part of a hoard of Korean-War or World-War-2 surplus small lenses and blanks of different sizes, some crowns, some flints. I think these were 2 flintrs that had been blanchard ground on one side and the other side moulded, but their overall shape was cylindrical, not convex or concave. No curve, if I recall correctly.So we put 2 of them together and it helped to spread out and diffuse the light from the laser. One alone wasn't enough; two of them together worked.
It's what we had on hand, and it worked.
But the monochromatic light box I made is better.
Dominic-Luc Webb <dlwebb at canit.se> wrote: On Mon, 3 Dec 2007 Hugues.Laroche at 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.
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Guy Brandenburg, Washington, DC
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