Optimum conditions for the high frequency noise reduction method in optical videodisc players.

In a previous paper, the authors demonstrated the usefulness of the high frequency (HF) current superposition noise reduction method. This paper discusses optimum conditions for the HF method. The main results obtained are that modulation current frequency must be higher than 600 MHz and modulation depth must be >120%. The optical path length between laser and disk and the removal for interference in the signal detectors must also be taken into consideration.