Patent ID: 7339975

Claim:
A laser beam synthesizing method comprising offsetting in different positions in a direction of a fast axis a plurality of beam bundles radiated from a plurality of semiconductor lasers, converging optical axes of the beam bundles in the fast axis view, and introducing the beam bundles into an end face of an optical fiber after converging them in the directions of the fast axis and a slow axis, wherein the improvement comprises: disposing a convergent angle transforming optical system between a converging optical system and a position where the optical axes of the beam bundles converged in the fast axis view intersect each other in the fast axis view, passing the whole beam bundle made up of the beam bundles converged in the fast axis view through the convergent angle transforming optical system so that the angle of convergence of the whole beam bundle or part of the beam bundles making up the whole beam bundle is made smaller in the fast axis view, and introducing the whole beam bundle into the end face of the optical fiber.