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Re: [Phys-l] A geek's observations on "Avatar"

At first I wondered why circular? Perhaps, so tilting head doesn't affect the 3D and if the screen is tall / wide also?

When I Disneylanded, I kept the glasses to use w/ my 3D projector (father's, and grandfather's glass slides from, ca 1903 to 1935). They are simple linear polarizers. I'm also surprised broad spectrum circular polarizers can be made cheaply. Are they not 1/4 wave plates w/ a lin. polarizer?

On 2010, Jan 03, , at 10:47, Leigh Palmer wrote:

I haven't contributed anything to this group in a long time, but thanks to an improvement in my physical health I feel inspired to do so again. This won't be deep physics, but it is interesting, especially for teachers going back into classrooms tomorrow.

Pleased you're back --


It is interesting to note that the package in which the glasses were handed out says:

These glasses do not screen ultraviolet
light. Wearing them as sunglasses will not
protect your eyes. Use only in the theater.
Keep out of reach of children under 3."

I think they've got this backwards, it's the IR that'll do the most damage. Especially bad as the iris' response is to the vis. Wiki. claims PMMA (most used optical plastic except for contacts) absorbance in the UV is similar to window glass. i.e. strongly absorbs < 0.3 E-6 m. and other sources show it's rather transmissive in the near IR. Same for polycarbonate, ~> 80% transmission vis to 1.8 E-6 m. Absorbs UV -- used for UV protection glasses


bc additionally saddened by father's death before acquiring the projector, and wonders what plastic the Avatar people are using.

p.s. In Galesburg returning from the AAPT Adv. Lab. Conference, I spent my allotment on a Taxiphote! It moves, by depressing a lever. stereo slides from a 25X tray up to the binoc. viewer. Cutely rings a bell after the last slide. Included locked drawer. I assumed the unlocked access door uses the same key, so took that look to smith who very surprisingly found an almost match (very rusted!). A little filing revealed five more nearly filled trays + more broken slides**. A few hours disassembly, cleaning. lubing and bending and it works well (smoothly). Can't understand why one (a child perhaps?) would continue braking slides after the first one or two!

** The Nile, Abu Simbel, etc. Unfortunately, Father's slides smaller, but more are available: