You can make your computer display "stealth": really? :) :D

An additional layer of security can be added to your computer. Sometimes it can be beyond your imagination. But still its amazing and fun to do such a master piece of security. :D :) 

Your LCD computer display can be provided with an extra security by following the lead of Brusspup, a well-known online illusionist and computer artist. You have to just remove your display's outer polarizing filter, and use polarizing sun glasses to view your display. It easy....right... :D :) 

without voltage and with voltage

An LCD display depends on liquid crystals that can rotate the polarization axis of light as it passes through. In fact LCD pixels are made up of numerous layers, a pair of linear polarizers and a thickness of nematic liquid crystal with transparent electrodes that can apply a voltage across the liquid crystal. What happens when a voltage is applied? the voltage causes the liquid crystal's rodlike molecules to line up with applied field. In that configuration there is no structure to alter the polarization of the light, so that light leaving the liquid crystal is still horizontally polarized. This light cannot pass through the vertical polarizer P1, so this appears as a dark pixel. Based on the voltage level, the pixel can let any amount of light pass through, from bright to dark. At the same time without voltage, the light is polarized horizontally by horizontal polarizer P2, then passes through a liquid crystal LC. The thickness of the liquid crystal is set to that it rotates the polarization of the light by 90 degrees. This converts the horizontally polarized light leaving polarizer P2 into vertically polarized light ready to enter vertical polarizer P1. Finally light passes through P1 and appears as a bright pixel. 

Brusspup who is also specialized in optical illusion noticed that if you completely remove polarizer P1, an LCD display shows uniform illumination with a varying pattern of polarization over the screen. However, our human eye is not very sensitive to the polarization of light with which it sees the world. The same way you might feel the LCD display to be bright and featureless when the final polarizing film of the display is removed. 

It means if you wear vertical polarizing filters over your eyes, you will see the original image and image is not visible to anyone else who is not wearing polarizing glasses. Interesting!! isn't it? Now you try at home... :) 

Its gives you a stealth display and added security along with fun too.... :D :) 

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