198046 ⎘
Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation , reproducing using an optical beam at lower power ; Record carriers therefor; Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam into, or out of, its operative position or across tracks, otherwise than during the transducing operation, e.g. for adjustment or preliminary positioning or track change or selection; Methods for track change, selection or preliminary positioning by moving the head; Methods and circuits to control the velocity of the head as it traverses the tracks to maintain constant velocity during the traverse