| US 7,583,580 B2 | ||
| Optical recording medium as well as optical recording and reproduction method | ||
| Kimihiro Saito, Saitama (Japan); Takeshi Yamasaki, Kanagawa (Japan); and Ariyoshi Nakaoki, Tokyo (Japan) | ||
| Assigned to Sony Corporation, Tokyo (Japan) | ||
| Filed on May 12, 2006, as Appl. No. 11/382,975. | ||
| Claims priority of application No. P2005-139988 (JP), filed on May 12, 2005; and application No. P2006-044303 (JP), filed on Feb. 21, 2006. | ||
| Prior Publication US 2006/0256695 A1, Nov. 16, 2006 | ||
| Int. Cl. G11B 7/00 (2006.01) | ||
| U.S. Cl. 369—112.23 [369/112.24; 369/275.5; 369/283; 369/286; 369/288] | 12 Claims |
| 1. An optical recording medium configured for recording and reproduction when illuminated by light from a light source as
near-field light using a focusing lens whose numerical aperture exceeds 1, comprising:
a composite layer, in which a high refractive index material portion having a refractive index higher than that of a light-transmissible
material portion is mixed in the light-transmissible material portion, provided on the surface of a light incident side of
said optical recording medium, wherein a refractive index n1 of said high refractive index material portion is
n1>NA
with respect to a numerical aperture NA of said focusing lens,
said high refractive index material portion is made of particles and an average particle diameter of said particles is equal
to or less than one tenth of a wavelength in said composite layer of light that illuminates said optical recording medium,
and
said particles having a particle size of approximately 22 nm or less.
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