Information recording medium, and apparatuses for reproducing, recording, and recording and reproducing thereof, and methods for reproducing, recording, and recording and reproducing thereof

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 recessed portion of the first microscopic pattern and the recessed 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 sidewalls of the recessed portion are parallel with each other, and
• further wherein a thickness of the second light transmitting layer is within a range of 0.02 mm to 0.04 mm.

An apparatus for reproducing 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 sidewalls of the raised portion are parallel with each other,
• the apparatus further comprising:
• a reproducing device for reproducing the first recording layer or the second recording layer of the information recording medium, wherein the reproducing device includes a light emitting element for emitting reproducing light having a wavelength λ of 350 nm to 450 nm and a noise of less than RIN (Relative Intensity Noise) −125 dB/Hz, and an objective lens having a numerical aperture NA of 0.75 to 0.9;
• and
• a control device for controlling the reproducing device to irradiate and to focus the reproducing light on the first recording layer or the second recording layer.

An apparatus for reproducing 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 recessed portion of the first microscopic pattern and the recessed 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 sidewalls of the recessed portion are parallel with each other,
• the apparatus further comprising:
• a reproducing device for reproducing the first recording layer or the second recording layer of the information recording medium, wherein the reproducing device includes a light emitting element for emitting reproducing light having a wavelength λ of 350 nm to 450 nm and a noise of less than RIN (Relative Intensity Noise) −125 dB/Hz, and an objective lens having a numerical aperture NA of 0.75 to 0.9;
• and
• a control device for controlling the reproducing device to irradiate and to focus the reproducing light on the first recording layer or the second recording layer.