Year 11 Physics Assignment: DVD Technology Nick Cooper
Over the past decade the world has embraced a new technology called DVD. DVD is the next stage in optical storage technology and looks to update the manner in which digital information is stored for the future. The technology itself holds several key underlying physical principles which function in order to create DVD's superior performance and capabilities. Through current and recent research many developments have opened the door for this new technology to be applied in the modern world. In the upcoming years DVD technology appears ready to completely replace and supersede media such as VHS tapes and CD-ROMs in every market including home entertainment, general computer use and business.
Firstly, today's DVDs are basically a more compact version of Compact-Discs (CDs), sharing the same 120mm form factor but holding a much greater amount of data on them, in fact around seven times more..
CDs can hold up to 650MB of data as compared to the 4.7GB that the standard DVD can hold. Fundamentally this all comes down to the manner in which the information is stored on the two media. CDs have data stored on them as an arrangement of reflective bumps called lands and non-reflective holes called pits which run in minuscule grooves in a spiral track around the disc. The stored data is then read by a 750nm wavelength infrared laser that identifies the reflections from the lands and pits and converts them as binary information. DVDs work on the same basis however the distance between tracks and the minimal distance between lands, otherwise known as pit-length are 2.16 and 2.18 times smaller respectively; therefore a higher bit-density is created over the same surface area as a normal CD. With the tighter spaces involved a narrower red...