Abstract: A laser source arrangement is provided for use in a laser instrument of a kind used to transmit a scan pattern to a target which is spaced from the laser instrument and to detect light reflected from the target. The laser source arrangement preferably comprises a laser diode for producing a laser beam used to form the scan pattern. The laser diode is characterized by astigmatism which is subject to variation with the temperature of the case of the diode. The arrangement further includes drive apparatus for driving the laser diode in a pulsed mode having a duty cycle which reduces the astigmatism and substantially controls the temperature dependence of the astigmatism. Optics are also provided for statically correcting the astigmatism of the laser diode.

Abstract: A power control system for controlling the power output of a modulated laser diode receives current pulses of a signal to be evaluated and establishes a DC voltage which represents the peak value of the light pulses out of the laser diode. An integrator feedback loop compares the desired power with the established DC voltage representing the peak value and causes the laser diode to make light pulses at the correct value. The control system includes a sample and hold which is constructed to act in association with the integrator feedback loop to perform at a rate in all substantial respects as if the modulated, chopped light output of the laser diode were continuously on and to produce in a symmetric manner effective control in real time both for an increase and for a decrease in the signal to be evaluated.

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.