Patent ID: 7379411

Claim:
A beam shaping device for converting laser light emitted from a semiconductor laser light source from an elliptic beam to a circular beam, wherein said beam shaping device is configured to receive a divergent beam from said semiconductor laser light source incident on a light-entrance-side surface of the beam shaping device, wherein light-entrance-side and light-exit-side surfaces of the beam shaping device both have a curvature only in a minor-axis direction of a cross section of the elliptic beam, wherein, of the light-entrance-side and light-exit-side surfaces, one is a circular-arc cylindrical surface and the other is a non-circular-arc cylindrical surface, and wherein the following conditional formula is fulfilled: 0.009≦ R 1/ R 2≦0.098 where, assuming that a radius of curvature of a surface convex to a light-entrance side or concave to a light-exit side is positive and that a radius of curvature of a surface concave to a light-entrance side or convex to a light-exit side is negative, with respect to the minor-axis direction of the cross section of the elliptic beam, R 1 represents a radius of curvature of the light-entrance-side surface of the beam shaping device; and R 2 represents a radius of curvature of the light-exit-side surface of the beam shaping device.