Hitachi Maxell, Limited

Akiyoshi Ito

Norio Ohta

Katsusuke Shimazaki

Katsuji Nakagawa

Kazuko Inoue

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 &#x3bb;, are different from those obtained upon reproduction at a wavelength &#x3bb;. The two magnetic layers, on which a signal (a) is recorded, are irradiated with light beams having the wavelengths &#x3bb;and &#x3bb;respectively. 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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Matsudo, Japan

Akiyoshi Ito