How It Works – The HD DVD Laser

As digital TV technology has taken hold and screen sizes have just gone on getting bigger, Standard Definition (SD) DVD has been exposed. It just can’t cut it any more. The bigger your screen gets, the worse your DVD picture gets. Anything over 36 inches and you’ll be harking back to the bad old days of VHS. By comparison, HD DVD can cut it up to 60 inches and beyond (according to consumer tests). Sad to say, while it’ll always be remembered for prompting the meteoric jump from VHS, the SD system is on its last legs.

It’s the things that set HD DVD apart that distance it absolutely from any meaningful comparison with SD DVD. HD DVD is much more than a higher definition iteration of the SD format. It’s still just over a millimetre thick, it’s got the exact same 12 cm diameter, but it can store a massive eight hours of ultra high quality HD video. And MP3? HD DVDs can store something in the reason of ten thousand tracks on a single sided disc!

Amazing! And it all comes down to lasers. Well, this is the twenty first century! HD DVD players utilise new blue-violet lasers (which operate at the opposite end of the visible spectrum from the red lasers used by SD DVD systems). The blue-violet wavelength occupies about 400 nanometres, compared with 650 nanometres in the red wavelength. To put that in perspective, 400 nanometres is about 250 times smaller than a human hair!

The combination of blue laser technology and advanced video compression techniques like MPEG-2. MPEG-4, AVC and VC-1 mean that at 15-25 gigabytes of information per layer, HD DVDs really can cram a lot of high quality entertainment into the same available space.

Think you can make room for one?