P3D Re: Projection problem

[Tom Hubin <thubin@xxxxxxxxx>]

Hello Paul,

> > Polarized glasses upside down will blank the screen. Right side up will
> > pass the images unchanged in polarization but about 75% as bright
> > (dimmer by about one stop).
> 
> That's the opposite of what I've observed.  Glasses right
> side up in front of the projector blank the screen; upside
> down they just dim the images.

Sounds like the left and right polarizers are swapped. That would give
you pseudo 3d but would not cause the ghosting. Or we may just not be
stating exactly how to try the glasses over the projector.

If you stand behind the projector wearing viewing glasses then remove
the glasses and place them over the projector, as if the projector is
your face, with the earpieces pointed toward the rear of the projector,
and the right lens over the right projector, the image should pass. If
the image is blocked then the right and left polarizers need to be
swapped or you need to be happy with pseudo 3d.
 
> > You can test your screen or
> > any screen before buying it.
> >
> > Shine a flashlight through a polarizer so that you now have a polarized
> > light source. Or you can use a laser pointer if you happen to have one
> > (assuming it is polarized). Shine the polarized light onto the screen
> > and look at the light through a polarizer. Rotate either polarizer
> > until you cannot see the light on the screen. If you can do this then
> > the light leaving the screen is still linearly polarized. If you cannot
> > reduce the light coming from the screen to your eye to a very low level
> > then it is not linearly polarized and ghosting will result.

Does your screen pass this test?

Tom Hubin
thubin@xxxxxxxxx