Patent ID: 6049512
Filing Date: 2000-04-11
Classification: G11B

Abstract:
An apparatus for writing information on two sides of a recording medium which is susceptible to being modified by impinging laser light, said apparatus comprising:a source of laser light;means for controlling the position of said laser light source;a first beam splitter for dividing laser light from said source into a far-side beam for writing on a portion of said medium on a side opposite to said source and into a front-side beam for use on a front portion of said medium which lies on the same side as said source;a second beam splitter for dividing said front-side beam into a first beam, for writing on said front portion of said medium, and into a second beam for tracking;a first reflective means for directing said tracking beam to reference track edges within said medium;means for varying the point of impingement of said tracking beam backward and forth across said tracks in an oscillatory manner at a frequency .omega..sub.T ;a photodetector means, positioned so as to receive a portion of light from said second beam splitter;filter means for extracting signals having spectra in the vicinity of .omega..sub.T to provide control signals to said control means for the positioning of said laser light source with respect to said reference tracks in said medium; anda second reflective means for directing said far-side beam from said first beam splitter to said side of said medium opposite said source.