Disc Reading
Objective lenses in conventional CD players have a longer working distance, or focal length, than lenses designed for SACD players. This means that when a hybrid SACD is placed into a conventional CD player, the laser beam passes the high-resolution layer and is reflected by the conventional layer at the standard 1.2 mm distance, and the high-density layer is out of focus. When the disc is placed into an SACD player, the laser is reflected by the high-resolution layer (at 600 µm distance) before it can reach the conventional layer. Conversely, if a conventional CD is placed into an SACD player, the laser will read the disc as a CD since there is no high-resolution layer.
Read more about this topic: Super Audio CD
Famous quotes containing the words disc and/or reading:
““What,” it will be questioned, “When the sun rises, do you not see a round disc of fire somewhat like a guinea?” O no, no, I see an innumerable company of the heavenly host crying “Holy, Holy, Holy is the Lord God Almighty.””
—William Blake (1757–1827)
“As one child psychologist friend of mine explains it with tongue in cheek, your baby only needs a lot of light at night if he’s reading or he’s entertaining guests.”
—Lawrence Kutner (20th century)