Blu-ray Dimensions

What is Blu-ray?

Blu-ray is not a misspelling but a trademarked name. Blu-ray is a format based off blue laser technology. Currently there are a number of blue laser technologies including Blue-ray, UDO, XDCAM, and ProData. Blu-ray is being specifically marketed towards the consumer sector by the Blu-ray Association (BDA). The ten companies involved are Hitachi, Ltd., LG Electronics Inc., Matsushita Electric Industrial Co., Ltd., Mitsubishi Electric Corporation, Pioneer Corporation, Royal Philips Electronics, Samsung Electronics Co., Ltd., Sharp Corporation, Sony Corporation, and Thomson.

Three formats are proposed: BD-ROM (read-only)2005, BD-R (write-once), and BD-RE (rewritable) format. Blu-ray is also referred to as blu-ray disc or BD.

Differences in Blu-Ray:

Blue laser formats have a shorter wavelength (405 Nanometers) then CD and DVD formats which use a red laser (650 nanameters (DVD read wavelength). Blue ray’s blue laser beam focuses much tighter then a red laser. This allows for much tighter alignment of pits (areas of darker contrast on a recordable disc). This tighter collection of pits allows for greater storage, 27GB with the first generation of single sided blu-ray media.

Blu-Ray discs will not have a cartridge like the professional blue laser formats (see our page on Sony’s ProData products). Instead a hard coating has been developed to protect the disc and lower production costs. Blu-ray discs also have the data stored close to the laser instead of sandwiched between two polycarbonate layers like DVD, or CDR which have have the data layer on top of the disc.

Blu-ray specifications call for a higher transfer rate of 36 Mbps (megabits per second) then DVD which is only 10 Mbps. At 1x this translates to about an hour and a half. The Blu-ray association is working on a V2.0 specification that will increase the speed to 2x. The recording speed is expected to increase in the future to even higher rates.

Professional versions of blue laser technology in 120mm dimensions include Sony’s XDCAM (for broadcasters and AV studios) and ProData (Professional Disc for Data). Plasmon also has ‘UDO’ which uses a slightly larger disc in the 130mm size. Standard CDs and DVDs use 120mm discs. Discs based off the 120mm technology will have an advantage in manufacturing over 130mm and thus cost less to produce.