Re: silver screens

[P3D Allan Woods <allanwx@xxxxxxxxxx>]

>>According to Da-Lite, their purpose is to reflect back towards the
>>center of the viewing area, some of the light that would have reflected
>>off to the sides if the screen were completely flat.  
>
>Ah, you must mean the other way around, eh?


If I may interject...

Some basic geometry and the knowledge that "angle of incidence = angle
of relection" for light will show that light entering into a reflective
notch whose sides are at 90 degrees will be reflected back along the path
of incidence.  This principle is widely used for surveying, but the
reflector is a "corner cube" which performs as above for light entering
along a radial axis.  A reflector is placed at the target end, and a light
or laser is shown into it and reflected directly back.  A modulation
imposed on the light will produce interference when comparing the
outgoing and incoming beams.  This interference is the basis for distance
calculations.  [The notch illustration only considers 2 dimensions - which
does not mead it is unsuitable for 3-D! ;-)]


>
>I've found out the hard way that Kodalith film, used for titles and
>masking, depolarizes.
>
>Unfortunately, 3D is matter of compromises...
>

The solution is simple - place the projection polarizers between the
film and the screen (rather than between the light source and the film).
That will obviate one "compromise."

allanwx@xxxxxxxxxx



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