P3D 3D with DLP projectors

[Andrew Woods <andrew@xxxxxxxxxxxxxxxxxxxxx>]

Larry Berlin wrote:
> Does anyone on the list have first hand experience with Digital Light
> Projection and stereo? I'm most interested in the issues and solutions
> regarding dual projectors and polarization...
> 
> It seems field sequential would be easy but require that the audience be
> equipped with active glasses, which could get expensive to set up.

The DLP projectors I've had experience with projected unpolarised light 
but this may vary from machine to machine.  Put a polariser at the lens 
of the projector and you will soon see what the nature of projector's
output polarisation is.

Even if the projector is polarised (as in LCD projectors) there are 
solutions - appropriate placement of polarisers will generally achieve
an appropriate result for polarised projection.

Forget field-sequential with DLP.  Most DLP projectors update the DMD
sequentially (like a CRT) but unlike a CRT, light comes from a particular
pixel for the entire period of the field (except when greyscales are
projected).  "pixels" in CRT projectors receive a quick burst of energy
from the electron beam and hence there is a "bit" of a dead period between
fields (during the vertical interval).  You don't get any dead period
with DLP projectors.

Cheers,
Andrew Woods.
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End of PHOTO-3D Digest 3213
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