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Signal Detection of Magneto-Optical Disk with Defocused Beam

Research Project

Project/Area Number 06650390
Research Category

Grant-in-Aid for General Scientific Research (C)

Allocation TypeSingle-year Grants
Research Field 電子デバイス・機器工学
Research InstitutionWakayama University

Principal Investigator

NUMATA Takuhisa  Wakayama University, Faculty of Systems Engineering, Professor, システム工学部, 教授 (80135673)

Co-Investigator(Kenkyū-buntansha) OKAMURA Yasuyuki  Osaka University, Faculty of Engineering Science, Associate Proffesor, 基礎工学部, 助教授 (80144442)
Project Period (FY) 1994 – 1995
Project Status Completed (Fiscal Year 1995)
Budget Amount *help
¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1995: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1994: ¥700,000 (Direct Cost: ¥700,000)
KeywordsHigh Density Optical Recording / Optical Disk / Magneto-Optical Disk / Optical Fourier Transform / Magneto-Optical Head / 高密度記録
Research Abstract

A readout method of high density magneto-optical disk was proposed. In this method, the recorded medium is not placed at the beam waist of the converging beam in the optical system like the conventional method but slightly off positioned from the waist. A circularly polarized beam is employed and the distribution of phase retardation in the illuminated area is discriminated with far-field diffraction pattern.
A theoretical calculation was established to estimate the far-field pattern of magneto-optical record, and was confirmed experimentally utilizing a magnetic garnet film with a large magneto-optical effect.
The performance of the defocused method depends on the amount of the defocusing and on the relative dimensions of the reversed domain with respect to that of the beam waist. The readout signal was calculated on the widely used magneto-optical disk material with several parameters of the optical system varied.
In reading a small isolated reversed domain, the readout signal decays with decrease of the domain diameter slowly than the conventional readout method, hence, the defocused method has an advantage of giving larger readout signal than the conventional method in this case. Depending on the diameter of the reversed domain, there exists a preferable amount of defocusing of several microns.
Since this method utilized the light diffraction at domains, the far-field pattern, i.e.the readout signal, grows and increases for the regular domain patterns. For a random domain pattern the readout signal deteriorates rapidly, and the estimation of this defocused method should be done under some code modulations.

Report

(3 results)
  • 1995 Annual Research Report   Final Research Report Summary
  • 1994 Annual Research Report
  • Research Products

    (14 results)

All Other

All Publications (14 results)

  • [Publications] T. Nakanishi et al.: "Deforwed Mo Loops: Appcanauce of Orthogoual Cowpouent of Maguetization" IEEE Trans. Magu.(予定).

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] 三谷健一郎他: "MO信号再生におけるデフォーカス法の検討" 光学連合シンポジウム講演概要集. 235-236 (1995)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] 財津英樹他: "TVカメラを用いた偏光角の2次元分布計測" 光学連合シンポジウム講演概要集. 363-364 (1995)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] H.Zaitsu: "Measurement of two-dimentional distribution of polarization rotation using TV camera" Japan Optics '95. 363 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] K.Mitani: "Study of Defocus Method in MO Readout" Japan Optics '95. 235 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] T.Nakanishi: "Deformed MO Loops : Appearance of Orthogonal Component of Magnetization" Intermag Conference. (1995)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] K.Higashi: "MO Readout Using Defocussed Beam" IEEE Trans.Magu.29. 3805-3807 (1993)

    • Related Report
      1995 Annual Research Report
  • [Publications] T.Kokogawa: "Figure of Merit in MO Readout with Polav and Trans. Kevr Effect" IEEE Trans.Magu.29. 3808-3810 (1993)

    • Related Report
      1995 Annual Research Report
  • [Publications] T.Nakanishi: "Deformed MO Loops : Appearance of Orthogoual Components of Maguetization" Digests of INTERMAG. CS20 (1995)

    • Related Report
      1995 Annual Research Report
  • [Publications] 三谷 健一郎: "MO信号再生におけるデフォーカス法の検討" 光連合シンポジウム講演予稿集. 235-236 (1995)

    • Related Report
      1995 Annual Research Report
  • [Publications] 財津 英樹: "TVカメラを用いた偏光角の2次元分布計測" 光学連合シンポジウム講演予稿集. 363-364 (1995)

    • Related Report
      1995 Annual Research Report
  • [Publications] K.Higashi et al.: "MO Readout Using Defocused Beam" IEEE Trans.Magu.29. 3805-3807 (1993)

    • Related Report
      1994 Annual Research Report
  • [Publications] T.Kokogawa et al.: "Figure of Merit in MO Readout with Polar and Transvase Kerr Effects" IEEE Trans.Magu.29. 3808-3810 (1993)

    • Related Report
      1994 Annual Research Report
  • [Publications] T.Nakanishi: "Deformed MO Loops:Appearamce of Orthogonal Components of Magnetization" IEEE Trans.Magu. 31(to be published). (1995)

    • Related Report
      1994 Annual Research Report

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Published: 1994-04-01   Modified: 2016-04-21  

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