Asahi Kasei Kabushiki Kaisha

Masato Terada

Isao Morimoto

Shuichiro Ogawa

Kazuyuki Furuya

Kazuhiro Nishimura

Tatsuya Okamura

A phase change optical disk having a reflectance relation of Rc<Ra and is adapted such that high recording characteristic can be obtained starting at a first recording time even when a recording operation is carried out without conducting an initialization process. For this purpose, a multiple reflection layer ( ), a first dielectric layer ( ), a recording layer ( ), a second dielectric layer ( ), a reflecting layer ( ) and an UV curable resin layer ( ) are provided on a substrate ( ). The recording layer ( ) is deposited at a temperature of the substrate during the deposition of the recording layer set to a temperature which makes the recording layer into a stable amorphous conditions and which is lower than a crystallizing temperature of the recording layer. Thus, the recording layer ( ) is deposited into a stable amorphous state.

Phase-changeable optical recording medium, method of manufacturing the same, and method of recording information on the same

An optical information recording medium comprising a thin plastic substrate of 0.6 mm or thinner, wherein the substrate is protected against strain without being limited by a film structure and a film formation condition. A single-layer or multilayer thin film (,) is formed on a plastic disk-like substrate having a center hole (,). This thin film (,) has a strain relief area (,) inside a recording area (,). This strain relief area (,) is formed by setting an outer diameter of an undeposited inner portion (,) to a value satisfying the following formula (1), for example: A,&lE;A,&lE;&minus;0.172P&plus;0.163 where A,: diameter of center hole, A,: outer diameter of undeposited inner portion, P: total strain occurring in thin film when film depositing.

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Fuji, Japan

Masato Terada