发明申请
US20100149932A1 OPTICAL RECORDING MEDIUM, AND OPTICAL INFORMATION DEVICE 有权
光学记录介质和光信息设备

OPTICAL RECORDING MEDIUM, AND OPTICAL INFORMATION DEVICE
摘要:
An object of the invention is to provide an optical recording medium and an optical information device that enable to improve the quality of a servo signal and a reproduction signal. In the case where shape-wise thicknesses tr1, tr2, tr3, and tr4 of a cover layer, a first intermediate layer, a second intermediate layer, and a third intermediate layer are respectively converted into thicknesses t1, t2, t3, and t4 of the respective corresponding layers each having a predetermined refractive index “no”, a defocus amount with respect to a layer having a refractive index nrα and a thickness trα (satisfying: 1≦α≦n (where α is a positive integer and n is an integer of 4 or more)), and a defocus amount with respect to a layer having the refractive index “no” and a thickness tα (satisfying: 1≦α≦n (where α is a positive integer and n is an integer of 4 or more)) are equal to each other; and the thicknesses t1, t2, t3, and t4 satisfy |t1−(t2+t3+t4)|≧1 μm, a difference between any two values of the thicknesses t1, t2, t3, and t4 is set to 1 μm or more in any case, and |(t1+t2)−(t3+t4)|≧1 μm.
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