Any links? I tried Google but Im not finding anything really technical. Are the wave lengths the same for CD and DVD? How does the player compensate for the faster rotational speeds used for all the video formats when playing a CD?
CD wave length is 780 nm, DVD is 650 nm. Both in the red spectrum, and as I understand it generally use the same laser, but I think some machines may use two in the red spectrum
Blu Ray is in the blue spectrum, with a wavelength of 405 nm. That requires a blue laser.
Hard optical discs read from the inside out, the opposite of the old LP. The disc details are in what is known as the lead in data. Unlike an LP, all optical discs are read at constant speed and NOT constant RPM. So the disc rotates much faster reading the inside than the outside. The outer part of the CD contains the lead out data.