Abstract: A blanking circuit used with an optical recording disk system for eliminating the effect of far field shift during high laser power writing on a disk. The circuit provides a differential output one-shot that is fired for a time long enough for write pulse transients to be gone from photo diodes in a light detector before the circuit switches are returned to a read mode.

Abstract: This invention relates to the field of radiant energy information storage devices and provides for a low reading level, an intermediate level and a high writing level of power from the radiation source so as to lower the overall power requirements of the radiation source and increase availability and accuracy of the verification read directly after or during writing, without causing unwanted damage to the information recording media. A circuit is described to accomplish this. The circuit basically employs two power sources, one for reading power, one for writing power and an intermediate ("Pedestal") circuit to employ a portion of the writing power source's power to provide the step-up in power to the intermediate level.

Abstract: In an optical recording system employing a semiconductor diode laser and having both read and write capabilities, the laser power must be carefully controlled at both the appropriate level for reading and at a different level for writing. Typically, a continuous read beam is emitted by the laser while pulses at the higher write power level are generated. The laser power control loop of the present disclosure maintains both the read and write output power of the laser within predetermined limits. A light sensing diode is used to determine laser output power, which is then used to operate the control circuit by adjusting the read and write current supplied to the laser. The output of the sensing diode voltage is passed through a read/write switch which is controlled by write pulses, which also control the laser. In read mode a DC signal is sent to a quad comparator circuit for read power control.