Thermally-induced recording with reduced harmonic distortion

In an information-bearing signal recorder having signal-recording means and means for relatively movably-mounted a thermally-repsonsive record-bearing member;

• the improvement in said recording means, comprising:
• a variable-energy-beam-emmiting source for emmiting a heat-inducing pulsed beam of energy directed to the record-bearing member for recording information-bearing signals on the record-bearing member and having an energy-controlling input portion;
• data means for supplying information-bearing signals to be recorded;
• first current-source means connected to said data means for receiving said information-bearing signals and connected to said beam-emitting source for responding to said information-bearing signals for supplying a first control pulse to the beam-emitting source to activate the beam-emitting source to emit said heat-inducing pulsed beam having a first energy level and a fixed-time duration;
• second current-source means connected to said data means for receiving said information-bearing signals and connected to said beam-emitting source for responding to said information-bearing signals for supplying a second control pulse to the beam emitting source to activate the beam-emitting source to emit a heat-inducing pulsed beam having a second energy level and of a duration representative of the information-bearing signals and in timed relation to said first energy level such that the first energy level of fixed duration occurs at a beginning first portion of the second-energy-level pulsed beam and such that the two energy levels sum to a recording-initiating value in the overlapping of the first and second control pulses;
• a rotatable disk comprising said record-bearing medium and having a plurality of radially-displaced circular record tracks for recording the information-bearing signals;
• and
• radial-position-control means for indicating the radial position of a track being scanned by the beam emitted by said beam-emitting source and connected to said data means, to said first current-source means and to said second current-source means and having control means responsive to said radial-position indication to variably delay the operation of the data means such that the current sources are activated at delays from time of receipt of said information-bearing signals in accordance with the indicated radial position and the amplitude values of the control pulses from both said current source vary with the indicated radial position such that a greater radial position results in a higher amplitude-control pulse and resultant greater energy level of emitted heat-inducing pulses.

In a magneto-optic data recorder having a controlled laser for emitting a heat-inducing pulse and optics for directing the emitted heat-inducing pulse to a magneto-optic record member, and magnetic means in operative relationships to the record member to magnetically bias the record member at the point of impingement of said heat-inducing pulse on said record member, for recording information-bearing signals on the record member and having means for relatively moving the record member and said laser such that the emitted beam scans a track on the record member;

• the improvement including, in combination:
• first means for supplying information-bearing data signals to be recorded on the record medium;
• and
• second means connected to said first means and to said laser for responding to said supplied data signals to activate said laser to emit respective ones of said heat-inducing pulses each having an initial fixed-duration, recording-inducing-intensity portion followed by a trailing portion having a recording-sustaining amplitude with the total time duration of the two portions being determined by the informational content of the signals being recorded such that the recorded data signals have a constant width along the track being scanned whereby a second harmonic of the data signals is reduced in amplitude.