Patent ID: 7242662

Claim:
An optical recording and reproducing medium comprising: grooves formed along recording tracks and which can be recorded and/or reproduced with irradiation of light having a predetermined wavelength λ, wherein, when n assumes a refractive index of a medium extending from a light entrance end face to said grooves of said optical recording and reproducing medium, a phase depth x of said groove satisfies the following inequality, x=λ/(d·n) in which d is a depth of the grooves: λ/16.14 n≦x≦λ/ 4.99 n and that a ratio w/p of a width w of said groove and a track pitch p satisfies the following inequality: 0.391( w/p )≦0.594, wherein the width w of said grooves is 135 nm to 185 nm and the depth of the grooves d is 99 nm to 114 nm; at least a recording layer and a protective layer formed on a substrate in which said grooves are formed and wherein said groove includes an upper surface projecting to the side near said light entrance end face and said upper surface of said groove serves as an information surface in which information is recorded and reproduced, wherein said grooves are formed as wobbling grooves, wherein said track pitch is greater than 300 nm and less than 325 nm, and wherein when NA assumes a numerical aperture of an objective lens for use in recording and/or reproducing said optical recording and reproducing medium, said NA lies in the ranges of 0.85±0.05.