Video disc read back scanner

Apparatus for optically reading information indicia stored in a plurality of substantially concentric information tracks formed in a disc-shaped information storage medium, said apparatus comprising:

• radiant beam means for producing a source beam of radiant energy to impinge upon the medium;
• means for rotating the medium relative to said source beam to produce a modulated beam of radiant energy representing portions of said source beam reflected from the medium;
• transducer means for receiving said modulated beam;
• optical means, defining an optical path, for directing said source beam from said radiant beam means to the medium and for directing said modulated beam from the medium to said transducer means, said optical means including means for focusing said source beam to a precise spot substantially the size of the information indicia on the medium, and said optical means further including first and second articulated mirrors disposed in said optical path, said first articulated mirror being arranged to steer said source beam in the radial direction relative to the medium and said second articulated mirror being arranged to steer said source beam in the tangential direction relative to the medium;
• translation means for translating the medium and said optical means relative to one another to cause the source beam to move from information track to information track in succession across the medium;
• and
• control means, responsive to said transducer means, for providing an error signal to said first articulated mirror indicative of radial deviations in the location of said source beam from a precisely selected location relative to an information track, said control means further providing an error signal to said second articulated mirror indicative of tangential deviations in the location of said source beam from a precisely selected location relative to an information track, such that said first articulated mirror and said second articulated mirror controllably guide said source beam along a precisely selected path relative to the information tracks on the medium as the medium and the optical means translate relative to one another.

Apparatus for optically reading information indicia stored in a plurality of substantially concentric information tracks formed in a disc-shaped information storage medium, said apparatus comprising:

• radiant beam means for producing a source beam of radiant energy to impinge upon the medium;
• means for rotating the medium relative to said source beam to produce a modulated beam of radiant energy representing portions of said source beam reflected from the medium;
• transducer means for receiving said modulated beam;
• optical means, defining an optical path, for directing said source beam from said radiant beam means to the medium and for directing said modulated beam from the medium to said transducer means, said modulated beam and said source beam having at least a portion of said optical path in common, said optical means including means for focusing said source beam to a precise spot substantially the size of the information indicia on the medium, and said optical means further including first and second articulated mirrors disposed in said common portion of said optical path, said first articulated mirror being arranged to steer said source beam in the radial direction relative to the medium and said second articulated mirror being arranged to steer said source beam in the tangential direction relative to the medium;
• translation means for translating the medium and said optical means relative to one another to cause the source beam to move from information track to information track in succession across the medium;
• and
• control means, responsive to said transducer means, for providing an error signal to said first articulated mirror indicative of radial deviations in the location of said source beam from a precisely selected location relative to an information track, said control means further providing an error signal to said second articulated means indicative of tangential deviations in the location of said source beam from a precisely selected location relative to an information track, such that said first articulated mirror and said second articulated mirror controllably guide said source beam along a precisely selected path relative to the information tracks on the medium as the medium and the optical means translate relative to one another.

Apparatus for optically reading information indicia stored in a plurality of substantially concentric information tracks formed in a disc-shaped information storage medium, said apparatus comprising:

• radiant beam means for producing a source beam of radiant energy to impinge upon the medium;
• means for rotating the medium relative to said source beam to produce a modulated beam of radiant energy representing portions of said source beam reflected from the medium;
• transducer means for receiving said modulated beam;
• optical means, defining an optical path, for directing said source beam from said radiant beam means to the medium and for directing said modulated beam from the medium to said transducer means, said optical means including means for focusing said source beam to a precise spot substantially the size of the information indicia on the medium and means for steering the source beam along a precisely defined path relative to the information tracks on the medium, said modulated beam and said source beam having at least a portion of said optical path in common, and said optical means further having beam separating means, including a beam splitting prism and a quarter wave plate disposed between said beam splitting prism and the medium, for separating said modulated beam from the path of said source beam and for directing said modulated beam along a path to said transducer means, said beam splitting prism being angularly oriented in said optical path such that portions of said source beam reflected by said beam splitting prism are directed along a path other than the path leading to said transducer means;
• translation means for translating the medium and said optical means relative to one another to cause the source beam to move from information track to information track in succession across the medium;
• and
• control means, responsive to said transducer means, for providing an error signal to said steering means indicative of deviations in the location of said source beam from said precisely defined path, such that said steering means controllably guides said source beam along said precisely defined path relative to the information tracks on the medium as the medium and the optical means translate relative to one another.