Polarization Fields are a new way of creating glasses-free 3D experience. Basically, it’s a light field display that uses multiple stacked LCDs. The technical and mathematical details are described in detail in our SIGGRAPH Asia 2011 paper. You can find a video explaining the technology and showing the results we got on that site too. The final polarization fields display will probably look something like this the photo below. Among others, this project was featured in articles by Wired and The Boston Globe!
In the depicted version, we use an older design for the frames. If you follow the instructions of setting up your base display, you should be able to get something a little nicer looking. In any case, the final display prototype is composed of four stacked LCDs. What’s special about this hardware design is that we only use two crossed linear polarizers around the entire stack (as opposed to one polarizer in between each LCD). Effectively, each pixel in the LCD stack acts as a programmable polarization rotator, as illustrated below. What comes out of the display (without the front polarizer) is what we call a polarization field – emitted light rays at different angles have all the same intensity but different polarization-rotation states. With the front polarizer inserted, this variation in polarization-state is optically converted into changes in intensity according to Malus’ law.
The scientifically interesting part about this project is that you can, under some assumptions, use computed tomographic algorithms (similar to those used in Layered 3D) to automatically compute optimal display pixel states for a given 3D scene (or light field). If you are interested in the details, please read our paper. We provide OpenGL-based source coded that does all the computed tomography in real time here. In the remainder of this site, we explain how to build the actual display prototype.
The first thing you need is a few LCDs. Follow the instructions on the building blocks part of this site to get them out of conventional computer monitors. For this project, we used medical grayscale monitors (Barco E-2320 PA IPS LCD) that have a resolution of 1600 x 1200 pixels and run at 60 Hz. You should be able to get good results with other panels too, but grayscale LCDs have no color filter arrays on them (which makes the Franken Display stack significantly brighter). Make sure to remove all polarizing films from the LCDs.
Stack up multiple LCDs on your base display – we used four. Simulations show that three may be good enough to get some effect as well, two are definitely not sufficient for this design. Things may get pretty dim with four LCDs, so we hacked the backlight of one of the screens by adding some more light power from one of the other backlights.
Here’s a result we captured from our first prototype display. You can see more results and clips in the video on our project page.