BEAM SHAPING ELEMENT, AND LIGHT SOURCE UNIT AND OPTICAL PICKUP USING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a beam shaping element that can correct the displacement of the light emitting point of a light source simply by performing positional adjustment within a plane vertical to an optical axis and then makes it unnecessary to perform positional adjustment along the optical axis, and to provide a light source unit and an optical pickup which use the same.

SOLUTION: The beam shaping element 4 includes on each side thereof a set of diffraction gratings 6 and 7 which are fabricated in such a manner that the grating constant W1 becomes narrower from the vicinity of an optical axis toward the circumference. Each grating constant W1 of the set of diffraction gratings 6 and 7 is so formed as to increase or decrease monotonously along a direction in which each grating-shaped pattern 6' and 7' extends. Further provided are the light source unit and optical pickup which use the beam shaping element 4.

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