Projection on glass

During last days, at Laboratori Ligabue, while testing frontal and retro-projection on a plexiglass surface, me and my teammates have found many interesting things:

1. You can’t get a good projection on pure glass because its low reflecting coefficient and high refractive index just make the incoming light beams deviate and not coming back. So you must use some kind of translucent layer to fix an image on the surface, that’s why we tested it on glossy paper and on vynil acetate to see where we had the best result;
2. Glossy paper is good, has slightly more brightness and it’s far more available and economic than acetate;
3. Glossy paper gives a frosty-glass look, and its a bit less bright than glossy paper, but it’s far more resistant.

Also we’ve made some attemps to understand how to place the projector: too close to the surface will result as a unfocused image, and if it is rotated, the output needs to be deformed with the trapezoidal rule.

A less economic solution is the SGG-Priva-Lite Technology glass. It’ s a patent of Saint Gobain Glass which consists in a layer of liquid crystals (connected to an electric source) within the middle of two glass surfaces. Depending of the orientation and disposition of crystals, glass become clear or translucent simply by hitting a switch. You can find a brief explaination looking at the skecthes below or visiting http://www.sggprivalite.com/.

The sketch above shows, on the left, a total cross-section (glass + liquid crystal films) then, on the right, the section of the sandwich in the middle consisting in many liquid crystal films overlapped and alternated with condictive coatings.

These last two sketches show (on the left) how the glass becomes translucent without electrical current by deviating light beams thanks to a random disposition and orientation of the crystal; then (on the right) how, instead, thanks to a passage of current, the crystal have a regular disposition and the same orientation, letting the light to pass through the glass without deviations and giving a clear view.

The primarly use of these special product is to mantain temporary privacy on particular places, as Rem Koolhaas and AMO (a division of OMA-Office for Metropolitan Architecture) did in 2001 for the dressing rooms of the Prada store in Soho, New York.

Image by Gizmag

Other solution consist are less expensive but not within everyone’s budgets (expecially universitary students: the Claro Holographic TV or the Wohenburk CrystalLine.

Image by Gizmag

This post will be constantly updated in future