| 摘要 |
A reflection surface is divided into four reflection areas by means of a horizontal surface, a vertical surface and a surface inclined with respect to the horizontal surface, the three surfaces respectively including the optical axis of the reflector. The four reflection areas include a basic surface. The basic surface is an aggregate (envelope surface) of intersection lines obtained when a virtual paraboloid of revolution, which includes a reference parabola in the horizontal surface or inclined surface and has as a focus (second focus) a point on an optical axis passing through the vertex and focus of the reference parabola and situated in front of or to the rear of a focus (first focus) with respect to the vertex, is cut by vertical surfaces respectively including the optical axis. The focal positions of the sections (parabolas) in the adjoining reflection areas are made to coincide with one another to make the boundaries of the reflected areas continuous with one another, and also the positional relation between a filament and the first and second focuses of each of the reflection areas is controlled. |
