The Collaborative International Dictionary of English v.0.48:

laser disk \laser disk\ n.
   A digital data storage medium consisting of a thin disk onto
   which the data is impressed by a laser, in the form of a
   linear sequence of dots; same as optical disk. The data is
   subsequently read back by the use of a laser beam. See also
   compact disk.

   Note: The original disk may be created by use of a laser, but
         copies of the original disk may be created by a
         replicating process which does not itself require a
         laser.
         [PJC]