At this year's IFA, HEXUS.lifestyle had the chance to sit down and interview Jim Armour from Toshiba's Storage Device Division. As you can imagine, the hot topic was HD DVD and how it is superior to Blu-ray. According to Jim, the way Blu-ray discs are constructed causes warping which can damage a player's lens.
HEXUS.lifestyle: But in just raw data storage, Blu-ray is going to be better as it holds more data. Jim Armour: Looking at the numbers on a bit of paper, you'd think so, but what you need to do is look at the Blu-ray discs and players first, before you make a decision. Let's go back to the disc construction for a second. HD DVD uses a sandwich method which helps to combat disc warping. Blu-ray doesn't. It uses a single plastic substrate layer, then adds on the recording material and then top it all off with a very hard Zircon layer. This means that when the disc expands to get hot, it will warp downwards as that Zircon layer isn't going to budge.
HEXUS.lifestyle: But that's a uniform direction of warping? Surely as long as you're ready for it, it won't make any difference? Jim Armour: You'd think so, wouldn't you? But now we have to go back to the lens. Blu-ray uses a 0.85 Numerical Aperture and, with their recording layer just 0.1mm below the disc surface, they've got to get the lens very close to the disc surface to be able to focus it tightly enough to give them a 25GB storage capacity. So now you've got a Blu-ray lens sitting somewhere between 0.1 and 0.3 millimetres from a disc coated with a substance almost as tough as diamond which, when it warps, can only warp downwards, towards the lens. Guess what happens when you run Zircon over glass at 2000rpm? Sure, your data will be safe but you're going to need a new Blu-ray lens.
At this point, I don't really think warping is an issue. However, as BD reading and writing speeds increase, this might change. If you'd like to read more, head on over to HEXUS.lifestyle.
