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| [* black] The glass over the E-ink screen takes the light from the eight LEDs at the top and evenly distributes it. | |
| [* black] How you ask? | |
| - | [* black] Optics. The glass is specially |
| - | [* black] Light coming from the LEDs goes into the glass |
| + | [* black] Optics. The glass is specially designed using two principles of optics: internal reflection and diffraction. |
| + | [* black] Light coming from the LEDs goes into the glass which has a [http://en.wikipedia.org/wiki/Diffraction_grating|diffraction grating] on it. This diffraction grating bounces the light around using internal reflection. Barnes and Noble really did their homework on this one, because instead of a simple linear diffraction grating, the diffraction grating seems to change throughout the glass to compensate for the local conditions. |
| [* black] How do we know its a diffraction grating? | |
| - | [* black] Lasers. We took a laser and pointed it at the glass. Unlike the light of the white LEDs found on the nook, the laser has a very limited wavelength, so when you shine it through the glass you see |
| + | [* black] [http://shaktronics.com/files/2010/02/big-scary-laser.gif|Lasers]. We took a laser and pointed it at the glass. Unlike the light of the white LEDs found on the nook, the laser has a very limited wavelength, so when you shine it through the glass you see the diffraction pattern in the picture. |