 While a DVD uses a 650 nm red laser, Blu-ray Disc uses a 405 nm "blue" laser diode.Although the laser is called "blue", its color is actually in the violet range.The shorter wavelength can be focused to a smaller area, thus enabling it to read information recorded in pits that are less than half the size of those on a DVD, and can consequently be spaced more closely, resulting in a shorter track pitch, enabling a Blu-ray Disc to hold about five times the amount of information that can be stored on a DVD.