Top of a Blu-Ray Disc
|Type||Optical storage medium|
|capacity||23.3 / 25/27 GByte (single layer)
46.6 / 50/54 GByte (double layer)
100 GByte (triple layer)
128 GByte (quad layer)
BD-R blanks are available with a different number of 1–4 layers. This property has a major impact on the possible storage capacity. There are:
- single-layer version stores 23.3 GB, 25 GB or 27 gigabytes
- two-layer BD-R DL (Dual Layer) up to 46.6 GB, 50 GB or 54 GB
- three-layer BD-R TL (Triple Layer) up to 100 GB (BDXL)
- four-layer BD-R QL (Quad Layer) up to 128 GB (BDXL)
As a storage medium, the BD-R uses a substance that changes its reflectivity depending on the optical density of the laser beam. The concrete composition is not specified; Both organic and inorganic substances (e.g. copper / silicon layers) can be used.
There are two different types of writing: HTL ( “High To Low” ) and LTH ( “Low To High” ). HTL media are more expensive than LTH, but last longer. Since LTH media was not part of the original Blu-Ray standardization, early Blu-ray players and burners may need a firmware update to handle LTH media.
The first media used the HTL principle ( “High To Low” ) and were based on the phase change technique , in which the recording layer consists of inorganic materials. This can only be used for one-time writing. Without writing, the writing layer is in a crystalline state with a high degree of reflection. The transition to an amorphous state is brought about by the heating by means of a laser beam and the degree of reflection is reduced. Writing changes the reflectance from high to low (HTL).
LTH media ( “Low To High” ) were added later, in which a layer of color is applied over a reflective layer. The color layer absorbs the light from the laser and causes a low degree of reflection. During the writing process, the absorption effect of the dye is reduced at certain points, thus increasing the degree of reflection. This technology was also used in the previous recordable formats DVD ± R and CD-R .
|Data rate||Writing time [min]|
|[ Mbit / s]||[ MB / s]||BD-R||BD-R DL||BD-R TL||BD-R QL|
-  Specification of the Blu-ray Disc Association from October 2010
- Media manufacturers are planning a new type of Blu-ray blanks on heise.de, accessed on March 1, 2014.
- BD-R New technologies ( Memento of the original from November 22, 2010 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. from media-tech.net, accessed on March 1, 2014.
- Blu-ray FAQ on blu-ray.com, accessed on March 1, 2014.