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 $20 Linear Polarization Modulator from Active 3D Glasses 
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One Eyed Hopeful
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Joined: Wed Feb 12, 2014 3:49 pm
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No longer do you have to resort to purchasing one of the $1,500+ polarization modulators for your 3D projector! A pair of modified active 3D glasses can deliver a virtually indistinguishable result. This solution allows for 3D Blu-ray and other commercial 3D input for linear passive projection, as well as the abolishment of an extra projector or alignment difficulties.

You will need:
- 3D capable projector (Able to accept 3D HDMI standard or whatever solution you use)
- Compatible 3D active glasses
- Silver screen
- Linearly polarized 3D glasses
- X-Acto knife
- Screwdriver (In my case, 2.0 mm Phillips head)
- Tweezers
- Some way to mount the glasses in front of the projector. Depending on your setup, you could even just put the active glasses on top of some books.


Introduction:
To the best of my understanding, 3D active glasses use two polarizing filters between a liquid crystal layer. this makes it so that when an electrical charge is run through the liquid crystal layer, the light coming through the first polarizer is reversed, and then cancelled out by the next polarizing filter , which maintains its polarization. This cancellation produces a black lens to block your view of the screen. Rapidly alternating each lens with this method allows for the active "shuttering".

Following this idea, if the outermost polarization filter is removed, the liquid crystal layer will reverse the polarization of the light coming through the first polarization filter, and alternate in sync with the projector. The polarized glasses will then translate this signal for each eye.

I used a Sony VPL-HW40ES 3D projector, some IMAX glasses from my local cinema, and the universal IR compatible PlayStation 3D glasses (Which I got for $20 on Amazon a few months ago). These PlayStation glasses should work on all Projectors that use IR 3D, and they are recharged through USB :D


The Guide:
The first thing we want to do is open up the 3D glasses. With the PlayStation glasses, there are six screws: two on the nose piece. and four beneath the arms. Remove all of these. Then, since there is minimal glue still, carefully work your way along the slit separating the two main parts of the glasses with the X-Acto knife and pull them apart. Be mindful of the battery when you separate them, as well as gentle with the ON/OFF switch, so that you don't break your 3D glasses.

Now we need to remove a polarizing filter. In my case, the removal of the inside filter on the right lens produced the correct synchronization with my polarized glasses. To remove the filter, look for the line between the filter and the liquid crystal lens and begin cutting against that line with the X-Acto knife. After you have a decent flap unattached, gently peel off the filter with the tweezers. Once done, you are ready to line it up with the projector.

This is really the simplest part. At this point, just line up the glasses horizontally in front of the projector. Since we cut off the filter on the inside of the glasses, we want to place the glasses in front of the projector backwards, so that the outside filter is between the projector and the liquid crystal lens on the active glasses.

Now just turn your 3D glasses on and make sure they are connected to your projector (with the PlayStation glasses, this means flipping the remnants of the ON/OFF switch and pressing the button on top), start up some 3D content, and you're good to go! If the 3D image appears inverted and your projector does not have the option to invert the 3D itself (like mine), you can either remove the inside filter on the left lens instead, or just place the glasses at a 90 degree angle to produce the same result. However, If you just change the angle, you may have to deal with a smaller screen size to compensate for the smaller surface area.

Good luck with your new, low-cost, low-maintenance 3D passive projection system!


Sun Jun 12, 2016 12:18 am
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Certif-Eyed!

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I'd say you need to be careful about heat dissipation. Light from a projector can make the plastic filter run hot and burn it.

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Tue Jun 14, 2016 6:06 pm
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One Eyed Hopeful
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Tril wrote:
I'd say you need to be careful about heat dissipation. Light from a projector can make the plastic filter run hot and burn it.


It is a very valid concern. I was mostly just excited about the simplicity of the project in comparison to the price point of the higher end modules :lol: but it's not perfect. I'm planning on continuing tests and seeing if I can implement this basic technique even better in the future with more heat resistant materials, as well as with both linearly and circularly polarized glasses. For now though, if it's able to run polarized 3D movies without two projectors, I'm set :woot


Fri Jun 17, 2016 7:36 pm
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Petrif-Eyed
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To keep the glasses cool there are two things you can do. An IR blocking filter (glass, not gel) to block heat from the HID lamp, and a fan blowing on the glasses to keep them cool(er).

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Last edited by geekmaster on Sat Jun 25, 2016 1:28 pm, edited 2 times in total.



Sat Jun 18, 2016 1:21 pm
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One Eyed Hopeful
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Joined: Wed Feb 12, 2014 3:49 pm
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geekmaster wrote:
To keep the glasses cool there are two things you can do. An IR filter (glass, not gel) to block heat from the HID lamp, and a fan blowing on the glasses to keep them cool(er).


Excellent idea! I hadn't thought of such a solution. Thanks :)


Wed Jun 22, 2016 1:32 pm
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Binocular Vision CONFIRMED!

Joined: Sat Jun 02, 2007 1:29 pm
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Location: Wenatchee, WA.
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Just another Kickstarter bubbling up from the depths of MTBS3d. Dime a dozen around here really....:) Seriously though, this is going to get me to dust off the projector, (and install that fresh bulb I never got around to......thx Palmer). Remember, I was first to call KS on this!


Sun Jun 26, 2016 1:49 pm
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