In this section, we provide instructions on some basic things that you will need to build your own FrankenDisplay. That includes topics, such as printing on transparencies (it is not as straightforward as you may think), ripping a transparent LCD out of a consumer monitor, and making some mechanical parts that will hold your FrankenDisplay in place. Below, you’ll find some basic examples of display components and where to get them; use the menu above for more involved parts.
Diffusing films. You can order high-quality (but expensive) holographic diffusers from Edmund Optics or Thorlabs. Special (and also expensive) holographic diffusers that have a custom diffusion profile (e.g., diffusing only horizontally but not vertically) are sold by Luminit. For the most part, we use inexpensive diffusers that our local arts & crafts supply store sells as some sort of craft paper. One manufacturer that we have extensively used and recommend is graphicsplastics (the .003″ and .005″ sheets are great). The best thing about the graphicsplastics diffusers is that they are polarization-preserving. When you stack multiple LCDs, you want to use as few polarizers as possible so preserving polarization is key! Also of interest here are electronically-switchable diffusers that can change their state from transparent to diffuse by applying voltage. We tested one from Saint-Gobain Glass a few years ago that worked fine.
Polarizers. Often used as photographic filters and always covering the liquid crystal cells of your LCD. The relative rotation between two overlapping polarizers determines the amount of light that is transmitted through them. The light that comes out of your computer monitor is linearly polarized! We get most of our linear polarizing sheets from American Polarizers. You can easily cut them into custom shapes. Regular filters will only polarize light within some wavelength band (e.g., visible) – you need to buy special (and more expensive) polarizers for other bands, such as infrared!
Lenslet arrays. The image above shows hexagonal fresnel lenslets that are very thin and have a relatively long focal length (~1″). Two of the main suppliers of lenslet arrays that we use are Fresnel Technologies and Mico Lens Technology.
Lenticulars. These are really just one-dimensional lenslet arrays composed of semi-cylindrical lenses. Micro Lens Technology sells large sheets of them. Sometimes, we make our own lenslet arrays by stacking two lenticular sheets rotated by 90 degrees. There is some astigmatism in this design, but it’s cheaper and, due to the resulting rectangular lenslets, easier to calibrate than most hexagonal arrays. If you try that at home make sure to have the flat side of the lenticulars facing the outside of the sandwich.
We hack projectors too. This is a projection lens that we ripped out of an old Barco projector that we found in the junk. Of course you can use conventional SLR camera lenses as well, but keeping the parts may save you some money.
These are two liquid crystal on silicon (LCoS) displays. If you buy them from optics suppliers, they are usually extremely expensive. We are lucky to have some friends at SiliconMicroDisplay – they will release their LCoS-based head-mounted display (HMD) display soon. We got a sneak-preview of that HMD, which included two high-definition LCoS displays that were just waiting to be harvested.