METHOD FOR SHAPING BEAM AT OPTICAL PICKUP DEVICE, OPTICAL PICKUP DEVICE AND OPTICAL INFORMATION PROCESSOR

摘要

PROBLEM TO BE SOLVED: To realize a suitable method for shaping a beam in the case where a plurality of semiconductor laser light sources are used. SOLUTION: The method for shaping the beam is that in an optical pickup device in which a luminous flux emitted from a semiconductor laser light source is made into a parallel luminous flux with a collimator lens and introduced onto the recording face of an optical recording medium via an objective lens, the sectional figure of the luminous flux which is made to be parallel by the collimator lens is shaped into a circle or a similar prescribed shape. The oval section of the luminous flux which is made to be parallel by the collimator lens 2 is contracted in the direction of the long axis with the refraction of a beam shaping prism 3.