| 摘要 |
PURPOSE:To minimize the influence of face blur and eccentricity, by forming the illumination luminous flux to an ellipse which is shorter in the direction of the radius of a hologram disc and has a high ellipticity and arranging a unidirectional focusing optical system between a concave mirror and a scanning face. CONSTITUTION:A reproducing illumination light 4 is a parallel beam, and the section of the luminous flux is an ellipse which is longer in the circumferential direction of a disc and is shorter in the direction of the radius and has a high ellipticity. The reproducing beam is a divergent light from a hologram in the direction of the radius of the disc. In a focusing optical system, a cylindrical lens 5 having the axis in the scanning direction is provided besides a concave mirror and is arranged between the concave mirror and the scanning face. Thus, since the focus point is not affected by face deviation DELTAtheta of the disc and the angle and the position of incidence to the concave 3, the influence of face blur and eccentricity of the hologram surface is minimized. |
