The numerical aperture of 0.85 for Blu-ray means the lens has to be made of glass, not plastic. These lens/diode combinations cost $90 as of last December. The lens is so close to the disc that the disc has to be protected by a hard coating just in case the two contact each other. HD DVD can use a standard plastic lens that is much less expensive than the glass lens. MPEG-4 encoding will allow the majority of movies to be able to be recorded on standard DVDs using today's red lasers. There are two problems with this method: 1) no room for extra features (such as previews which are a form of commercials); and 2) no new royalty payments to the patent holders. Blue laser technology is being introduced for the benefit of the manufacturers, not consumers.
