The structure of a Blu-ray Disc
The Blu-ray Disc is an optical disc with the same dimensions as the DVD disc: 12cm in diameter and 1.2mm in thickness. By using a combination of the 405-nm-wavelength blue-violet laser, which is a shorter wavelength than the red laser used by DVD, and a high-density objective lens with a numerical aperture of 0.85, BD uses a laser beam spot that is only about 1/5 the size used by DVD. Thanks to these technologies, a single-layer Blu-Ray disc can store five times more data than a DVD disc.

1. One Single-Layer Disc Equals Five DVDs in Data Capacity
The Blu-Ray disc boasts a data storage capacity of 25GB in a single layer and 50GB in a dual layer, because it uses the shorter wavelength blue-violet laser and a high-density objective lens to enable higher-density data reading. When a multi-layer system is adopted in the future, the storage capacity can increase to 100GB and even 200GB. One Blu-Ray Video disc can store a huge amount of data so users can enjoy many hours of high-definition content and high-quality surround sound that could not previously be provided by other media.

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2. HD Image Quality Video
In addition to the MPEG-2 format used by DVD-Video, the Blu-Ray disc uses video codecs, such as MPEG-4 AVC and VC-1, which deliver high image quality using high compression rates. The data transfer speed is 48Mbps, which is about three times faster than DVD. A future plan also calls for a further increase in the data transfer speed. These technologies allow long-time playback of content with high definition image quality.

3. High Quality Surround Sound
The Blu-Ray disc optionally supports next-generation surround sound formats like 'Dolby® Digital Plus'. Connecting a Blu-Ray player to an AV centre using an HDMI cable enables linear PCM multi-channel data transfer. This makes it possible to reproduce high-quality 7.1-channel surround sound with each channel offering DVD-Audio quality, delivering a surround sound experience that rivals the quality of the master audio source.

4. Blu-ray Java™ for Extensive Interactive Functions.
The Blu-Ray disc is equipped with an extended functionality based on Java™ technology, called Blu-Ray Java to provide various interactive features. For example this can be used to program various operations, such as displaying a pop-up menu while playing a Blu-Ray disc, and activating a keyword search. With unlimited application possibilities, Blu-Ray Java offers interactive enjoyment that is simply not possible with conventional AV software.

(Java™ and all Java-based trademarks and logos are trademarks or registered trademarks of Sun Microsystems, Inc. in the United States and other countries.)

5. Extensive Support for Both Hardware and Software.
The Blu-ray Disc specifications have been established mainly by leading electronics, PC and gaming manufacturers around the world, including Panasonic. These companies will support Blu-Ray promotion by introducing a variety of hardware. A number of major motion picture companies have expressed their support. A large variety of Blu-ray titles are now available.