Ricoh Company, Ltd.

Takeshi Kibe

Hiroshi Miura

Shinya Narumi

Masaki Kato

Katsuyuki Yamada

Hiroshi Deguchi

Satoshi Taniguchi

Hajime Yuzurihara

Eiko Hibino

Yoshitaka Hayashi

Noboru Sasa

Toshishige Fujii

Mikiko Abe

Masayuki Fujiwara

To provide a sputtering target for preparing a recordable optical recording medium characterized by comprising Bi and B and a manufacturing method thereof, a recordable high density optical recording medium using the sputtering target, and a sputtering target which is capable of improving a speed of the film formation for the improvement of productivity, which has a high intensity at the time of the film formation and which has a heightened packing density.

Sputtering target and manufacturing method therefor, and recordable optical recording medium

An optical disc having a transition linear velocity of 8-11 m/s when irradiating continuous light with 11&#xb1;1 mW and a wavelength of 660&#xb1;10 nm using a pickup head with a numerical aperture (NA) of 0.65, and satisfying the following condition:&#x394;|&#x2266;3%where Rb is a reflectance of an unrecorded area, and Ra is a reflectance of the top of an eye pattern after ten cycles of recording. In one recording mode therefor, the disc is rotated at a constant angular velocity so as to have a linear velocity of 3-4 m/s on an innermost track and a linear velocity of 8-9 m/s on an outermost track. In another mode, the disc is rotated at a constant angular velocity so as to have a linear velocity of 5-6 m/s on an innermost track and a linear velocity of 13-14 m/s on an outermost track.

Optical recording medium

An optical disc having a transition linear velocity of 8-11 m/s when irradiating continuous light with 11&#xb1;1 mW and a wavelength of 660&#xb1;10 nm using a pickup head with a numerical aperture (NA) of 0.65, and satisfying the following condition:&#x394;R=|Rb&#x2014;Ra|&#x2266;3%where Rb is a reflectance of an unrecorded area, and Ra is a reflectance of the top of an eye pattern after ten cycles of recording. In one recording mode therefor, the disc is rotated at a constant angular velocity so as to have a linear velocity of 3&#x2013;4 m/s on an innermost track and a linear velocity of 8&#x2013;9 m/s on an outermost track. In another mode, the disc is rotated at a constant angular velocity so as to have a linear velocity of 5&#x2013;6 m/s on an innermost track and a linear velocity of 13&#x2013;14 m/s on an outermost track.

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Isehara, Japan

Takeshi Kibe