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A pair of Warner engineers have been working on a way to get all three formats to hold hands on a single disc, and have recently filed a patent to that effect. This is made possible by the fact that Blu-ray uses a 405nm laser to read its 0.1mm deep info layer, while HD DVD uses the same blue laser wavelength at the depth of 0.6mm. The hybrid disc works by making the Blu-ray layer act like a two way mirror, reflecting enough light for Blu-ray playback, but letting enough light through for HD DVD operation. As for DVD, that layer can be found on the flip side of the disc.

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