An optical disk the size of a CD (12 cm diam.), capable of storing 25 GB of data on a single-layer, up to 50 GB on dual layer disks. Data is transferred using 405 nanometer blue-violet lasers. Maximum data transfer rate is 54 Mb/s for audio and video for Blu-ray Disc movies, 40 Mb/s for video only. A disk will hold more than 90 minutes of HD material on a single layer, about 13 hours of SD material.canonglossaryus
Blu-ray (BD) is an optical disk storage medium superseding the DVD format. It can store six times more data than a DVD. The name refers to the blue laser used to read the disk. Blu-ray disks normally have a capacity of 25 gigabytes. Double sided Blu-ray disks have a capacity of 50 gigabytes.