| 摘要 |
Light having entered a light transmitting member through a predetermined point (the light emission center of a light emitting element) on an optical axis undergoes internal reflection in a front surface perpendicular to the optical axis, then undergoes internal reflection again in a rear surface composed of a paraboloid of revolution having a focal point at a position of plane symmetry with the predetermined point, and then exits the front surface. An annular region around the optical axis in the front surface is mirror-finished. The position of its outer peripheral edge is set to be near a position where the incident angle of the light emitted from the light emitting element is equal to a critical angle. The position of the inner peripheral edge is set to be near a position where the light having exited the light emitting element and undergone internal reflection in the front surface enters a position immediately behind the outer peripheral edge in the rear surface. |
