Blu-ray Disc

Blu-ray disk was introduced as a replacement for traditional DVD. It’s underlying technology is optical storage which is  as same as CD/DVD and it’s main usage is storing high definition videos, Play Station 3 games, and other data up to 50 GB. Blu-ray disc allows around 10 times more data storage as it uses a 400nm blu-violet laser wavelength while a standard DVD uses a 650nm red laser. With single layer, it can store up to 25 GB and with dual layer, it can store up to 50 GB. These are the standard Blu-ray drives’ storage. Now 200 GB discs are available, and 100GB discs are readable without extra equipment or modified firmware. It has the same physical dimension as standard DVDs and CDs.


The Blu-ray Disc Association developed Blu-ray disc. The first Blu-ray disc prototype was unveiled at the CEATEC exhibition as DVR Blue in October 2000. On February 19, 2002, the project was officially announced as “Blu-ray”. On October 4, 2004 the 20th Century Fox joined hands with BDA’s Board of Directors. The first BD-ROM players were shipped in mid-June 2006. The first movie released in Blu-ray is 2003’s Charlie’s Angels:Full Throttle. This release used the standard DVDs MPEG-2 compression method.

The Technology

Laser and Optics

To read and write data the Blu-ray disc uses a blue or violet laser, which is operating at a wavelength of 405nm. The diodes are InGaN (Indium Gallium Nitride) lasers that produce 405 nm photons directly, that is, without frequency doubling or other nonlinear optical mechanisms. Conventional DVDs and CDs use red and near-infrared lasers, at 650 nm and 780 nm, respectively. The blue-violet laser’s shorter wavelength makes it possible to store more information on a 12 cm CD/DVD-size disc. The minimum “spot size” on which a laser can be focused is limited by diffraction, and depends on the wavelength of the light and the numerical aperture of the lens used to focus it. By decreasing the wavelength, increasing the numerical aperture from 0.60 to 0.85, and making the cover layer thinner to avoid unwanted optical effects, the laser beam can be focused to a smaller spot. This allows more information to be stored in the same area. For Blu-ray Disc, the spot size is 580 nm. Blu-ray Discs feature improvements in data encoding that further increase the capacity.


To avoid the scratches, the Blu-ray disc has scratch-protection coating names Durabis.

Blu-ray with Java

The Java platform for Blu-ray players is called BD-J, which is based on JavaME Personal Basis Profile (PBP) v 1.1. It contains the additional APIs such as JavaTV and special Blu-ray API. In addition, it is based on a subset of JavaSE 1.4.2, so it uses the standard JVM. This includes Vector graphics, network support and file system access etc. The network connectivity is mandatory for Blu-ray profile 2 with support of TCP/IP and HTTP. For security, the secure connection contains the Java Socket Extension. A Blu-ray play can contain flash disks, a hard-disc or a USB port for extra memory. The file system classes allow accessing the file systems.

The BD-J platform uses AWT for its Graphical User Interface (GUI) with support of a remote control navigation. The Java Media Framework (JMF) is used for playback of the content on the disc. With the Java sandbox security, the user only allowed to access the disc publisher allowed servers. The main reason for incorporating Java in Blu-ray players it to get better possibilities when creating menus, in contrast to DVD players which use a simple MPEG based technology. Another basic feature is the possibility to add interactivity while playing the movie.

The Blu-ray Profiles

Each Blu-ray player must adhere to a specific profile. This specifies such things as the memory requirement. All profile with video requires a full BD-J implementation. This is a short summary of the current profiles:

  • 1.0 – This is the profile that is used today. It requires that the player has at least 64 KB persistent memory.
  • 1.1 – This becomes mandatory on all players that are manufactured after November 2007. The memory requirement is increased to 256 MB. The players must have a secondary video decoder and a secondary audio decoder. The secondary video decoder is used for picture in picture, whereas the secondary audio could be used for audio commentary etc.
  • 2.0 – This is called BD-Live and this requires the player to have network connectivity. The memory requirements are set to at least 1 GB. The memory is not limited to built-in memory, but could also be an external memory, such as an USB memory stick.
  • 3.0 – This is an audio only profile. This does not require BD-J.

The Blu-ray with Java platform can bring a new revolution in the field of movie publishing. We can expect our favorite movies with a very good quality in near future.


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