North American Philips Corporation

George C Kenney

Robert McFarlane

Eric J Frankfort

Apparatus for recording data by means of a beam of radiation on a recording medium which upon exposure to the beam undergoes optically detectable changes in the form of pits, which apparatus includes means for reducing the beam intensity as a result of pit initiation thereby forming more accurate pits.

Apparatus for controlling the write beam in an optical data recording

An electromagnetically deflectable device includes a mirror pivotally mounted to a support by means of a silicone based resilient element. An electromagnetic deflection coil is fixed to the mirror underside. The coil lead wires are embedded in the resilient element and pass through the element to the support.

Electromagnetically deflectable device

A closed loop control system for an optical recording apparatus of the read after write type comprises a comparator for comparing the input data signal with a playback signal derived from the read beam which trails the write beam and is modulated by the data pattern inscribed on the recording medium by the write beam. The error signal generated by the comparator is applied to a controller which varies the modulation of the read beam in dependence on the error signal, for example, by modifying the data signal used to drive the write beam modulator. In this way, the control system compensates for nonuniformities in the recording medium and the like so as to ensure that the pattern inscribed by the write beam accurately represents the data to be stored.

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Ossining, NY, United States of America

George C Kenney