A Blu-ray disk is an optical storage device similar to CD and DVD technology. It also uses a laser to read and write to the disk, but instead of a red laser beam, as used in DVD and CD, it uses a blue-violet laser beam.
This means it can burn smaller pits on the disk and so it has even more storage capacity than a DVD.
A single layer Blu-ray can store 25Gb whilst a double layer Blu-ray can hold up to 50Gb of data.
Blu-ray is commonly used to store high definition films (HD).
You can also purchase a blu-ray burner for home use as a backup device or to store home movies.
There are three format in the specification.
- BD-ROM - read-only format for distributing HD films, computer games, software etc
- BD--R one-time recordable format for HD video recording and data storage
- BD-RE rewritable format
There are also plans to make a BD/DVD combination that has Blu-ray and DVD formats on the same disk so it can be played in both DVD and Blu-ray players.
A single layer disk (25GB) can hold about 4 hours of high definition video or about 12 hours of standard definition video. This huge capacity is very useful for storing training courses in video format.
|Advantages of Blu-ray||Disadvantages of Blu-ray|
|Very large storage capacity 25-50 Gb||Blu-ray does not work in DVD or CD drives|
|Sound and picture quality is excellent, making them ideal for storing HD films.||They can be easily damaged by breaking or scratching|
|Blu-ray disks are now mass produced so they are relatively cheap||Using a Blu-ray for backup means that up to 50 GB of data is stored on disk, which may then break. That is a lot of data to lose. Perhaps splitting it into several DVD is less risky.|
|A hybrid Blu-ray / DVD disk can be read in both a Blu-ray and DVD player|
|Type of storage||Optical|
|Data access||Direct access|
|Cost of storage||Blu-ray cost more per byte of storage than hard disks or magnetic tapes.|
|Capacity||25 Gb (single layer) to 50Gb (double layer)|
|Speed||Slower than a hard disk or flash memory, faster than magnetic tape|
Fairly portable. Too large to fit into a pocket, but will easily fit inside a bag. Can be carried between home/school/office.
Easily scratched by general wear and tear or by not protecting it in a plastic case. Scratches on the disk surface can damage the data being stored
Needs to be protected from extremes of heat.
Has a limited number of read/write cycles.
If scratched, the data might not be able to be read.
Needs a computer with a Blu-ray drive in order to read the disk. Cannot be read by a CD drive or DVD drive.
Challenge see if you can find out one extra fact on this topic that we haven't already told you
Click on this link: Blu-ray recording equipment