A reflection mirror for a vehicle lamp

摘要

To form a reflection surface, a free curved surface conformed to a configuration of a car body is set for a fundamental surface of a reflection surface. A group of paraboloids of revolution having different focal distances are set, thereby to determine a group of closed curves as the lines of intersection of the fundamental surface and the group of paraboloids of revolution. Respective paraboloids of revolution are partially allotted to a portion between each pair of the adjacent closed curves of the closed curve group. As a result, a number of reflection steps arranged in multiple loops are formed in a state that the central part of the looped reflection steps is offset from the principal optical axis of the reflection mirror.