A beam shaping lens for shaping an incident beam having an elliptic cross
section into an outgoing beam having a substantially circular cross
section includes a first plane which is a cylindrical surface having a
generating line curving to form a non-circular cylindrical surface as an
incidence side of the incident beam and a second plane which is a
circular cylindrical surface as an outgoing side of the outgoing beam.
The distance between both ends of the generating line of the circular
cylindrical surface is larger than the distance between both ends of the
generating line of the non-circular cylindrical surface.