| 摘要 |
PROBLEM TO BE SOLVED: To facilitate design of an optical element, etc., and to improve a recording/reproducing characteristic by making aberration of light immediately after outgoing from an optical guide member a specified value or below. SOLUTION: This pickup is constituted so that the aberration of the light M immediately after outgoing from the optical guide member 5 to an optical medium 27 is made 0.03λ or below. Where, 2 is the wavelength of the light outgoing from a light source 1. As the method making the aberration of the light M 0.03λ or below, a diffusion angle conversion hologram 7 and a diffraction grating are made prescribed shapes, and their surface states are adjusted. Thus, the design of the optical elements such as an objective lens 26, etc., arranged between the medium 27 and a surface 5e are facilitated, and manufacture is simplified. Further, since the aberration of the light in the vicinity of the medium 27 is made 0.08λ or below, a size of a beam spot is reduced, and a recording/reproducing characteristic is improved. |
