Re: Project-or-View screen

[P3D Richard Young <young@xxxxxxx>]

> Jaap Zonneveld wrote:
> >He had success with a clear plastic of the name PERSPEX, that does not
> >depolarize.
>
> "Perspex" is the same material as "Plexiglass" in the USA.  I don't know
> how easy it is to obtain anymore...most of the stuff I see in places
> like Home Depot is acrylic, not Plexiglass, don't know if acrylic
> de-polarizes or not.

I tested all the clear acrylics available at our local plastics store and none
of them depolarize. The problem is in the coatings, or in the internal
pigmentation, which is placed in the material that allows you to project an
image onto the material. These usually depolarize the
light, except in special cases. A light abrasion will give you somewhat
non-depolarized images on back-projection, but does not scatter the light
enough to give you any good off-axis viewing, and it is also hard to make
it so you don't have uneven light on your image. So I don't have a good
solution yet.
- Dick Young



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