re: Transmax

[P3D Larry Berlin <lberlin@xxxxxxxxx>]

>>Paul Ivester writes:
>>Subject: re: Retina "Beamsplitter"  and New Polarizing Material
>........ Quote snipped............

>It's easy to pre-judge claims like that, based on insufficient information.
>My initial reaction was that 50% was the theoretical maximum, so I didn't
>see how they could claim 70% transmission. I finally looked up the articles,
>and it looks like they may have come up with a very clever way to get around
>the limitation.
>
>For stereo projection, it sounds like there would be both a challenge and
>perhaps a great opportunity. I don't have the article(s) at the moment,
>but from memory, the high transmission depends on multiple reflections from
>a scattering surface, which works for a diffuse light source such as a flat
>panel backlight, but which might not be optimum for projection. (I'm not
>very familiar with projector geometries, so take that with a grain of salt.)
>
>The opportunity: I recently posted a speculation that it would be nice if
>the light from a projector bulb could be split into two polarizations and
>used for the two views, rather than splitting the unpolarized light and
>filtering with separate polarizers. This device might do the trick. I believe
>the article stated that the light is sent to a sheet of cholesteric liquid
>crystal material, and that this material passes about half the light with
>one circular polarization, and reflects about half with the opposite
>circular polarization. If the transmitted and reflected light could be
>separated out, and the circular polarization preserved, then for a single
>bulb stereo projector, instead of each view getting ~20% of the light from
>the bulb, each view could get nearly 50% of the light from the bulb (minus
>various inefficiencies in both cases, of course), a ~150% improvement!
>
>Comments? Opinions?


*******  Sounds like something with promise.

A question, since some varieties of slide depolarize the light, is there
still an advantage to polarization ahead of the slide? If this loss were
corrected with a second polarizer after the slide would overall efficiency
be increased or decreased by having a pre-polarized light source?

If there is an advantage to polarized light ahead of the slide, couldn't an
arrangement of prisms and reflectors and beam splitters designed to polarize
and collect in a similar fashion to the description above, be persuaded to
provide the desired twin polarized beams without any liquid crystal being
involved? In other words, does the clever strategy work with any other
materials or arrangements thereof?

How heat resistant are cholesteric liquids?

Larry Berlin

Email: lberlin@xxxxxxxxx
http://www.sonic.net/~lberlin/
http://3dzine.simplenet.com/


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