Abstract: The invention relates to an apparatus for the reproduction or recording of data or information with a photodetector and digital error signal and evaluation signal processing. The object of the invention is to provide an apparatus for the reproduction or recording of data or information which requires little outlay despite digital evaluation signal processing and a considerable capability of adaptation to different scanning speeds. The invention is based on the principle of enabling digital evaluation signal generation with an analog-to-digital converter known from audio technology, even though the data rate of the data or high-frequency signal requires an analog-to-digital converter for the radio-frequency or for the video signal band. An analog-to-digital converter for the audio frequency band can be used to generate a digital evaluation signal by the analog-to-digital converter having fed to it not the high-frequency signal directly but rather at least one envelope of the high-frequency signal.

Abstract: The invention relates to a method and a circuit arrangement for a laser control loop with automatic adaptation to the monitoring signal polarity. Use is made of a single-phase method which consists in that a signal produced by the monitor during the starting phase of the laser control loop is compared with a reference value, and in accordance with the result of the comparison the signal produced by the monitor is fed directly or inverted to the comparator for controlling the light power of the laser during the starting phase of the laser control loop. A signal is produced which initially feeds the comparator for controlling the light power the inverted monitoring signal, or directly feeds the monitoring signal, in a fashion always independent of the monitoring signal polarity, but dependent on the polarity of a reference value, and feeds it in a non-inverted fashion in the case of a monitoring signal running up to the reference value.