Patent ID: 8259551

Claim:
An optical information device which executes reproduction or recording for an optical recording medium, the optical information device comprising: an optical head unit including an objective lens and a laser light source; a motor rotating the optical recording medium; and an electric circuit which receives a signal obtained from the optical head unit and controls and drives the motor, the objective lens or the laser light source, wherein the electric circuit corrects a spherical aberration generated on an intermediate layer between a first surface and a second surface at which the focus jump is to be made and moves a focal position, wherein the optical recording medium comprises: a first information recording surface closest to a medium surface of the optical recording medium where light is incident; a second information recording surface second closest to the medium surface; a third information recording surface third closest to the medium surface; a cover layer having a refractive index nr 1 and formed between the medium surface and the first information recording surface; a first intermediate layer having a refractive index nr 2 and formed between the first information recording surface and the second information recording surface; and a second intermediate layer having a refractive index nr 3 and formed between the second information recording surface and the third information recording surface, and wherein in a case where actual thicknesses tr 1 , tr 2 , and tr 3 of the cover layer, the first intermediate layer, and the second intermediate layer are respectively converted into effective thicknesses t 1 , t 2 , and t 3 of the respective corresponding layers each having a predetermined standard refractive index “no”, defocus values of both the actual thickness and the effective thickness are the same, the effective thicknesses t 1 , t 2 , and t 3 satisfy | t 1−( t 2 +t 3)|≧1 μm, a difference between any two values of the effective thicknesses t 1 , t 2 , and t 3 is set to 1 μm or more in any case, and the standard refractive index “no” is set to 1.60.