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US 2003/0148060 A1Published application
Optical disc
AssigneeVictor Company of Japan, Ltd.
InventorsAkira Nishizawa, Tetsuya Kondo, Takeo Kojima
Life of this patent
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Abstract
An optical disc has a support base and at least one information-retrieval layer formed over the support base. The information-retrieval layer is transparent and thinner than the support base. The information-retrieval layer exhibits variation in birefringence within ±20 nmpp (nano meter peak to peak) under double-pass measurements during one rotation of the optical disc.
Claims8
An optical disc comprising:
- a support base;
- and
- at least one information-retrieval layer formed over the support base, the information-retrieval layer being transparent, thinner than the support base and exhibiting variation in birefringence within ±20 nmpp (nano meter peak to peak) under double-pass measurements during one disc rotation.
An optical disc comprising:
- a support base;
- and
- a transparent sheet acting as an information-retrieval layer, stuck over the support base, the sheet being thinner than the support base, the sheet exhibiting variation in birefringence within ±20 nmpp (nano meter peak to peak) during one rotation under double-pass measurements.
An optical disc comprising:
- a support base;
- and
- a transparent sheet acting as an information-retrieval layer, stuck over the support base, the sheet being thinner than the support base, a draw ratio for the sheet being adjusted so that the sheet exhibits variation in birefringence within ±20 nmpp (nano meter peak to peak) during one rotation.
Dependencies are inferred from the claim text.