Improved gap control system using a disturbance observer for near-field recording

Jung Gon Kim, Min Seok Kang, Tea Wook Kwon, Jun Jeong, No Cheol Park, Hyun Seok Yang, Young Pil Park

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

In a solid immersion lens (SIL) based near-field recoding (NFR) system which is one of the emerging technologies for next-generation optical data storage systems, it is essential that the air gap between the SJL and the rotating disk is maintained at less than 50nm without collision in order to obtain the proper coupling efficiency of evanescent waves. To fabricate a reliable near-field air gap servo system, various disturbances such as disk vibration, external shock and overshoot have to be considered, and these possible disturbances have to be prevented effectively. We propose an improved gap servo system using a disturbance observer (DOB), which has a reduced overshoot and rejection performance for the previously mentioned disturbances. The effectiveness of the proposed controller is verified by experimentally. The experiment results, show that the overshoot was reduced using the proposed near-field air gap servo system with a DOB. In the case of the ramp approach mode with and without the hand-over mode in the mode-switching servo, the overshoots were decreased to 50.9% and collision was avoided, respectively. In addition, in the case of the modified approach mode with and without the hand-over mode in the mode-switching servo, the overshoot was decreased to 2.9 and 3.7%, respectively. Consequently, the access time was decreased in each approach case without the hand-over mode using the DOB-based controller. In addition, the disturbance rejection performance of the external shock was improved to 9.11%.

Original languageEnglish
Pages (from-to)5947-5952
Number of pages6
JournalJapanese Journal of Applied Physics
Volume47
Issue number7 PART 2
DOIs
Publication statusPublished - 2008 Jul 18

Fingerprint

Servomechanisms
near fields
disturbances
recording
Control systems
Air
Optical data storage
Controllers
Disturbance rejection
Rotating disks
Lenses
rejection
air
controllers
shock
access time
collisions
evanescent waves
rotating disks
data storage

All Science Journal Classification (ASJC) codes

  • Engineering(all)
  • Physics and Astronomy(all)

Cite this

Kim, Jung Gon ; Kang, Min Seok ; Kwon, Tea Wook ; Jeong, Jun ; Park, No Cheol ; Yang, Hyun Seok ; Park, Young Pil. / Improved gap control system using a disturbance observer for near-field recording. In: Japanese Journal of Applied Physics. 2008 ; Vol. 47, No. 7 PART 2. pp. 5947-5952.
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Improved gap control system using a disturbance observer for near-field recording. / Kim, Jung Gon; Kang, Min Seok; Kwon, Tea Wook; Jeong, Jun; Park, No Cheol; Yang, Hyun Seok; Park, Young Pil.

In: Japanese Journal of Applied Physics, Vol. 47, No. 7 PART 2, 18.07.2008, p. 5947-5952.

Research output: Contribution to journalArticle

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