| 摘要 |
PROBLEM TO BE SOLVED: To set appropriate values of power, a defocus variation and a focus setting range on a recording medium. SOLUTION: A light beam emitted from a laser coupler 1 is reflected by a mirror 2, and is incident upon an anamorphoscopic prism 32 after being collimated by a comllimator lens 31. The incident light beam on the anamorphoscopic prism 32 is enlarged in diameter in the direction of an X-axis, irradiating a mirror 3. The light beam reflected by the mirror 3 is incident upon an objective lens 4 to be converged on the recording medium. |
