Characterization of a novel focusing/tracking technique with increased feedthrough immunity for optical-disk applications: The double-astigmatic method

Bruce E. Bernacki, Keith Bates, M. Mansuripur, Delbert Hansen, Daniel Cisneros

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

The astigmatic-focusing/push-pull tracking-error detection method is an elegant and sensitive optical servo technique. Unfortunately the formation of error signals far from either line focus of the astigmat (for relaxing alignment tolerances and broadening the servo’s acquisition range) gives rise to undesired diffraction effects in the focus servo channel owing to track crossings of the pregrooved disk by the optical stylus, especially if certain aberrations are present. These undesired effects are given several names: Pattern noise, optical servo cross talk, and feedthrough. By combining two astigmatic lenses and their associated detectors, one can configure a differential variant of the astigmatic technique. This double-astigmatic method greatly reduces pattern noise caused by the presence of spurious astigmatism oriented with its line foci at ±45° to the disk tracks. In this paper we present numerical modeling and experimental data that demonstrate the effectiveness of this focusing/tracking technique in feedthrough suppression.

Original languageEnglish (US)
Pages (from-to)5789-5796
Number of pages8
JournalApplied optics
Volume32
Issue number29
DOIs
StatePublished - Oct 10 1993

Keywords

  • Differential focus-error detection methods
  • Double-astigmatic method, optical heads
  • Feedthrough
  • Optical data storage
  • Pattern-noise cancellation

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Engineering (miscellaneous)
  • Electrical and Electronic Engineering

Fingerprint Dive into the research topics of 'Characterization of a novel focusing/tracking technique with increased feedthrough immunity for optical-disk applications: The double-astigmatic method'. Together they form a unique fingerprint.

  • Cite this