Researchers at National Taiwan University say that groups developing next-generation DVD players may not have to use blue lasers as expected (US 2004/32822).
The short wavelength of blue lasers means they can focus on smaller data spots – the dots and dashes etched into the disc that encode the content. But blue lasers are hard to make. NTU says the spots on high-density discs can be read with cheaper red lasers, if the disc is coated with a lensing layer.
The lens layer comprises several coatings of zinc oxide. Refraction at these oxide layers focuses the red light, giving the same high resolution as blue light focused through external optics.
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