OTHER TECH

But the truly important difference is that while a DVD is composed of two plastic substrates sandwiched together with the data layer in between, a Blu-ray Disc is made of one plastic substrate with the data covering the bottom and protected by a special coating only 0.1 millimeter thick. The Blu-ray's one-layer construction is a throwback to the CD and has many things in common with the Super Audio CD (SACD), both developed by Sony and Philips, as well as to the now forgotten Sony/Philips proposal for their version of the original DVD, which lost out in the DVD Forum to the Toshiba/Warner system we use today. (Forgotten, that is, except by Sony and Philips.)

The crucial difference here is that while the laser shines through the plastic substrate to read the data in the CD, DVD, and SACD systems, the laser in a Blu-ray system strikes the pits through what on a CD would be the label side - it comes in from the back! A Blu-ray Disc substrate doesn't even have to be transparent! The significance of this is that cheaper plastics might be used, I hope from remelted AOL discs.

The HD DVD system is itself a throwback to the sandwich construction of laserdiscs. The equations that govern the optical scanning on a laserdisc and all its derivatives (CD, DVD, SACD, and BD) lock certain physical parameters of the laser, the lens system, and the disc construction into a mathematical relationship so intimate that altering even one parameter would require changing all the others. That's precisely the situation here. While the data carried on a BD and an HD DVD could in theory be made identical, the differences in the discs' construction and optical properties create irreconcilable differences. There can be no compromise.

Just how bitter the custody battle over the next, and perhaps final, generation of consumer optical storage has become was made even more apparent by a recent article in The Wall Street Journal that reported the Blu-ray group of companies was being investigated by the Justice Department for acting "in concert to impede the [DVD] Forum's technical progress." Apparently members of the Blu-ray group that are also members of the DVD Forum abstained from voting for the Forum to adopt HD DVD, "effectively blocking approval of Toshiba and NEC's proposal." Later, the rules were changed so abstentions wouldn't count, allowing the Forum to endorse HD DVD.

Not even in the days preceding the standardization of the CD or DVD formats were the Feds so interested in such goings-on as to launch investigations. If that has indeed occurred here, you have to wonder who called them in, and for what purpose. The whole matter is getting incredibly ugly and brutal - and the movie studios haven't even chimed in yet.