Blu-ray is a technology developed by Sony to replace DVD. The purpose of this was to provide High Definition (HD) picture quality.

Standard DVD screen is 720×480(NTSC) and 720×576(PAL).

Blu-ray is 1920×1080.

As you can see this is considerably more pixels per frame, in fact 6 times more data!

So a new high capacity technology was required. After some hard fought media standards battles with Toshiba, the film industry finally settled on Sony’s Blu-ray technology.

This required a different surface chemistry for the discs and a new laser wavelength so more data could be stored over the same surface area.

Blue lasers were chosen instead of the DVD’s red. The wavelength values escape me at the moment.

A complementary article I have also written on Ezine is “Choosing a Blu-ray Player“.

A Blu-ray disc (BD), has it’s data stored at a narrower wavelength by use of blue-violet laser. The blue-violet light has a wavelength of 405nm (nanometers) where as the DVD’s red laser operates at 650nm. By looking at these figures directly, it may appear that there isn’t that much difference between the values but, not only is data stored more closely together around the disc but also closer in a radial direction.

In addition the aperture of the laser lens has been altered thus providing storage of 25GB and 50GB worth of data depending on number of layers provided on the disc.

DVD players are definately being phased out as all Blu-ray players can play DVD discs. Just look how cheep DVD players are now in your local stores.

DVD discs will probably be around for quite a while longer, as millions of people have numerous DVD discs and won’t make the move to BR until they are forced to do so. Most computers still have DVD recorders and until Blu-ray drives become the norm then DVD discs will continue. BR recorders are available but they are still very expensive and out of range for a lot of people.