Differential wax-wane focus servo

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


We describe a differential wax-wane focus servo technique for use in optical data storage. A combination of scalar diffraction modeling and experiment is used to quantify performance. Our results indicate that the differential technique is superior to the single-detector wax-wane technique with respect to gain, linearity, and lock-on range. We present modeling results that show the effects of aberrations and detector misalignment. The differential system was found to be robust. It can also reject many common pattern noise effects such as tracking cross talk, which was reduced from 0.7 μm in a single channel to < 0.1 μm in the optimized differential channel.

Original languageEnglish (US)
Pages (from-to)4797-4807
Number of pages11
JournalApplied optics
Issue number25
StatePublished - Sep 1993


  • Focus servo
  • Optical data storage

ASJC Scopus subject areas

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


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