Optical pickup device and recording medium used therefor

An optical pickup device for use in recording and/or reproducing data with a recording medium, comprising:

• a light source to produce a light beam having a wavelength longer than 650 nm;
• an objective lens having a numerical aperture (NA) of 0.7 or more and which uses only two surfaces to focus the light beam received from said light source to form a light spot on the recording medium;
• and
• a light detector which receives and detects the light beam reflected from the recording medium.

A recording medium comprising:

• a substrate;
• a recording layer disposed on said substrate and comprising a material suitable for recording data using light having a wavelength of 700 nm or more;
• and
• a protective layer which is disposed on said recording layer and transmits incident light, said protective layer having a thickness that is at or between 40 nm and 0.6 mm.