| 摘要 |
PURPOSE:To more nicely erase signals, by splitting a wavefront of an optical beam against a recording surface and, at the same time, irradiating the optical beam through a wavefront splitting optical path deflecting means which performs optical path deflection or an optical beam converting means which has a wave surface curvature converting function. CONSTITUTION:An optical beam emitted from an erasing semiconductor laser 2 becomes parallel rays 21 after passing through a condenser lens 4 and the rays 21 are divided into parallel luminous flux groups 22A-22C of different courses when they are made incident on a wavefront splitting deflecting means 20 (prism). Thus deflected luminous fluxes 22A-22C reach a stop lens 12 after they are subjected to the reflection by a polarization beam splitter 8, transmission by a 1/4-wave plate 10, reflection by an optical filter 11, and transmission by the 1/4-wave plate, polarization beam splitter 8, and a 1/4-wave plate, and an erasing optical spot 23 is formed by the stop lens 12. Since the incident angles of the luminous fluxes 22A-22C made incident on the stop lens 12 are different from each other, optical spots 23 are formed at different locations and a spot shape suitable for erasing can be obtained. |
