Blue Ray Strategy

HD DVD vs. Blu-ray technology

Comparing HD DVD with Blu-ray technology was far from being straightforward as they were both regarded as the high definition optical disc format that was to eventually replace the DVD standard. Although both technologies had very similar features they were mutually incompatible.

Both HD DVD and Blu-ray systems could play the current red laser DVD discs but the key to the innovation laid in the use of blue-violet lasers that operated at the other extreme of the visible light spectrum (around 400 nanometers instead of 650).

* The key to the technological innovation laid in the use of blue lasers. These operate at the other extreme of the visible light spectrum from the current DVD players, which use red laser technology. The difference is in the wavelength, 400 nanometers for blue lasers compared to 650 for red. While both HD DVD and Blu-ray systems could still play DVD discs, the shorter wavelength and …

* The shorter wavelength and increased numerical aperture allowed a much larger data storage capacity in the same amount of space. Compared to the standard 4.7 GB DVD, HD DVD offered three times more (15 GB) and Blu-ray more than five times the capacity (25 GB). Also, HD DVD discs had the possibility of coming in double sided versions, increasing the total capacity to 30 GB. Blu-ray discs had the advantage that recording and playback could be done from one side, meaning users did not have to turn the disc over in the drive. The wavelength and numerical aperture combination went also in favor for Blu-ray as it resulted in a higher maximum data transfer rate than for HD DVD (53.95 Mbit/s against 36.55).

An important difference could be observed in the discs themselves: While HD DVD used a similar disc to the DVD (i.e. a 0.6 mm disc with a 0.6 mm protection layer), Blu-ray stepped away from the standard and used a 1.1 mm disc with only a 0.1 mm protection layer. The first generation of Blu-ray discs was therefore more...