Bit error analysis for optical disks.
This analysis deals with the effect of an opaque foreign substance contained in an optical disk substrate on the waveform distortion of the readout signal after recording by using wave optics. The defect amplitude distribution (DAD) and the reductive rate distribution (RRD) of peak intensity were defined as the 2-D representations of the defect signal before recording and the peak intensity of the beam spot focused on the recording plane, respectively, and it was shown that DAD was almost unaffected by diffraction from pregrooves or recorded dots and that RRD characterized recording degrees of disk film. Using DAD and RRD and others, the distribution of signal amplitude distortion (SAD) which represented two-dimensionally the waveform distortion of the readout signal after recording was derived. The cross section of SAD on the threshold voltage was related to the bit error rate, and, by calculating the cross section for various conditions, the bit error rate was estimated and it was clear that the probability of SAD exceeding the threshold voltage was proportional to the cube of the diameter of the foreign substance.
Nishiwaki
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