Patent ID: 7709110
Filing Date: 2010-05-04
Classification: G11B,Y10T

Abstract:
1. An information recording medium at least comprising: a substrate; a second recording layer formed on the substrate for recording information; a second light transmitting layer formed on the second recording layer; a first recording layer formed on the second light transmitting layer for recording different information from that recorded in the second recording layer; and a first light transmitting layer formed on the first recording layer; the second recording layer being formed with a second continuous microscopic pattern of a plurality of raised portions and recessed portions formed alternately viewed from the first light transmitting layer side; and the first recording layer being formed with a first continuous microscopic pattern of a plurality of raised portions and recessed portions formed alternately viewed from the first light transmitting layer side and different from the second microscopic pattern; both the first microscopic pattern and the second microscopic pattern satisfying a relation of P≦λ/NA, wherein P is a pitch of the raised portion, λ is a wavelength of reproducing light for reproducing the first recording layer and the second recording layer, and NA is a numerical aperture of an objective lens; and a sidewall of the raised portion of the first microscopic pattern and the raised portion of the second microscopic pattern being continuously wobbled in alternating sections corresponding to auxiliary information and a reference clock, wherein the auxiliary information is a frequency-shift keying modulation wave having two different frequencies and the reference clock is a sinusoidal wave having a single frequency respectively, and wherein both the first microscopic pattern and the second microscopic pattern are formed on a same shaped portion either on a raised portion or on a recessed portion, and further wherein both sidewalls of the raised portion or the recessed portion on which a microscopic pattern is formed are parallel with each other with respect to both the first microscopic pattern and the second microscopic pattern.