| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical lens having a high refractive index, to provide a condensing lens which is suitable for a near-field recording and reproducing system by using it and to provide an optical pickup device and an optical recording and reproducing device which cope with a high density and a large capacity of an optical recording medium. SOLUTION: The main component of a first optical lens 2 is constituted of GaN, or the first optical lens 2 is constituted of a GaN single crystal having the crystal structure of a cubic system, or the first optical lens 2 is constituted of the GaN single crystal having a crystal structure of hexagonal system, and the size of a luminous flux made incident on a second optical lens 3 is made small, and the condensing lens 4 is constituted of the first optical lens 2 and the second optical lens 3. In this case, the NA(numerical aperture) of the condensing lens 4 is set to be >=1.5, and the condensing lens 4 is made small in size and light in weight. |
