Method for recording and reproduction on a magneto-optical...

Dynamic information storage or retrieval – Storage or retrieval by simultaneous application of diverse... – Magnetic field and light beam

Reexamination Certificate

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C369S275100

Reexamination Certificate

active

07113453

ABSTRACT:
A magneto-optical recording medium and a method for recording and reproduction thereon are provided in order to reproduce information recorded by multi-valued recording at a high S/N ratio. Disclosed is a magneto-optical recording medium including two magnetic layers capable of four-valued recording based on four combined magnetization states. Magnitudes of reproduction signals concerning the four magnetization states, obtained upon reproduction at a wavelength λ1, are different from those obtained upon reproduction at a wavelength λ2. The two magnetic layers, on which a signal (a) is recorded, are irradiated with light beams having the wavelengths λ1and λ2respectively. Signals (d), (e) reproduced from respective reflected light beams are sliced by using at least one slice level to obtain two-valued or higher multi-valued reproduction signals respectively. The two-valued or higher multi-valued reproduction signals (f), (g) from the respective wavelengths are mutually subjected to logical operation to reproduce recorded information (i).

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patent: A-8129784 (1996-05-01), None
Saito et al, “Multi-valued Magneto-Optical Recording in TbFe Compositionally Modulated Films,” 1989; Digests of the 13th Annual Conference on Magnetics in Japan; Proceeding of 13th Congress of Applied Magnetics Society; p. 63.
Saito et al., “Multi-valued Magneto-Optical Recording in TbFe/SiO Compositionally Modulated Films,” 1989; Proceeding of the International Symposium on Optical Memory; Japanese Journal of Applied Physics, vol. 28 (1989) Suppl. 28-3; pp. 343-347.

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