Circular Polarization and 3D Movies?

[AdmiralKnight]

Has anyone gone to see one of these new 3D movies? The other Optician I work with saw one over the Christmas holidays and it got us talking. I hated wearing those cheap, crappy 3D glasses. They were huge, hurt my nose, and I know I wasn't the only one thinking that. My associate agreed with me. After doing some quick research, we found out that IMAX 3D uses linear polarized lenses just like we use for sunglasses, except one lens is flipped 90 degrees. We made up a pair of clips and I tested them out over the weekend when I saw Alice in Wonderland... failed epicly. :bbg:

After looking at the site of the manufacturer of said crappy lenses, we found out that they use "Circular" Polarized lenses. Can anyone shed some light as to what these are, and how they work? Neither of us had ever heard of Circular POlarized lenses and we were curious if anyone else had! :cheers:

[kcount]

Never heard of that one, but would encourage a test by taking two uncuts and turneing them at 45 and 135 degrees. Wonder if that does the trick... or better yet bring home a pair and test them with a polarscope.

[finefocus]

"Circular Polarization" was the mechanism (along with A/R coats or pierced mesh) in anti-glare computer screens, back when CRT's were used. Maybe Kensington or another computer gadget mfg could elucidate.

[Barry Santini]

Ophthalmic Polarizers are linear. When linear ones are used for 3D, they're often set at axis 45 OD and 135 OS (complementary).

Circular polarizers affect the polarization axis by changin it's phase over time - think stretched-out slinky spring.

To provide the correct "handedness" for 3D, you have clockwise(or rt-handed) polarization and Counter-clockwise (or LT handed Polarization.

You should be aware that Eyenovate is bringing out circular polarizers for their magnetic eyewear (aka clip ons). I tried to make a mag clip with the Avatar Polarizers, but they're insufficiently rigid for the eyenovate mounting.

FWIW

Barry

[finefocus]

try www.opticalfilters.co.uk/ws/displayfilters/polarizing_filters.html

[kcount]

Actually, we in Opticianry are behind, seems the Camera shop in your town can source what you need. The prices I found online are comparable with a typical Ophth. lens blank. Might be worth a call to your local Camera shop for a pair of filters. You may even be able to work out a deal where you'll provide photograpers clip's with premounted filters.

FWIW

[HarryChiling]

You'll see them referred to as wave plates or retarders, me and Fezz were having a colorful conversation about their application on the drive to SC this past weekend. Your gonna want a quarter retarder to change from linear to circular.

You can pick them up from edmund optics, the old Briot Scanforms used to have issues blocking up polarized lenses because the displays LCD was aligned improperly, you needed a retarder to see the underlying lens image to block it properly.

[jmchapman]

I made a pair of glasses with polar A lenses at 45 and 135 just for this purpose, I also put my RX in them. When I get the time I'll check to see if it works at all

[jmchapman]

Just think, if 3D really catches on, and we can start making 3D custom RX eyewear for patients, that would be HUGE

[sharpstick777]

There is no standard. Different 3D movies use different color tints and different types of polarization. Some use circular, some use linear at different angles. You can google "3D glasses", there are many lists of movies and the type of glasses they require.

Circular Polarizers have been used on cameras for years. The work better than linear do for Digital Cameras with autofocus and don't require precise filter placement, although the degree of polarization is less than a linear. I am a photo nut, and both have their places. I do use a linear but auto focus takes a long time so its not good for action shots.