9 - Sources of Noise in Magneto-Optical Readout

Abstract

The signal-to-noise ratio, along with the media intrinsic defect level, determines the realizable capacity and the data rate of an optical disk storage system. This chapter analyzes the various sources of noise encountered in optical storage and discusses the spectral nature of the noise. The chapter also develops the relationship among noise, jitter, and system byte error rate (BER). Although the focus is on magneto-optical (MO) disk storage, most of these sources are known to occur in other optical recording systems as well. The arguments of the present discussion, therefore, may be adapted and applied to other media and systems. System performance can be improved by understanding and quantifying the various noise sources. The chapter has three objectives: to serve as a brief tutorial on the nature of noise in optical recording, to quantify the noise sources associated with MO recording media, and to discuss the limits of reducing noise and improving jitter and BER. The chapter briefly reviews the MO readout scheme.