Causes of focus-error feedthrough in optical-disk systems: astigmatic and obscuration methods

Bruce E. Bernacki, Masud Mansuripur

Research output: Contribution to journalArticle

4 Scopus citations


This paper discusses the phenomena of feedthrough which is a result of the interaction of the tracking-error signal (TES) with the focus-error signal (FES) in optical disk systems using push-pull tracking in grooved media. A computer model is used to study the FES and the optical beams phase distribution and intensity along the optical path and describe its mechanism and cause. The astigmatic and obscuration methods are used for the analysis and show that when 45° astigmatism is present the astigmatic yields the largest FES feedthrough. The two causes investigated were the phase and amplitude distribution of the reflected beam at the exit pupil of the objective lens.

Original languageEnglish (US)
Pages (from-to)735-743
Number of pages9
JournalApplied Optics
Issue number5
Publication statusPublished - Jan 1 1994


ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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