| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical pickup device, a condensing optical system, and a method for recording and reproducing optical information, by which a large volume of optical information are recorded and/or reproduced with an optical information recording medium of which the aerial recording density and the volume recoding density are both increased compared with that of a conventional medium. SOLUTION: An evanescent light E arrives at the recording medium RM before the light E decays when the distance A between a nearly hemispherical lens HL and the upper face of the recording medium RM is set small (not greater than the wavelength of the light source of a passing light, for example), and therefore the light is used for the purpose of recording or reproducing the information. In other words, the condensing optical system of which the numerical aperture(NA) on the side of an image is 1.0 or greater is composed by recording or reproducing the information by using a light beam which is totally reflected beyond a first prescribed angle θ1 to a second prescribed angle θ2 . |
