An illuminating waveguide having first and second longitudinally-extending unitary
portions of differing cross-sectional shape. In use, light is injected into the
waveguide at, for example, an end face of the waveguide and the light travels along
the length of the waveguide with a portion of the light refracting laterally out
of the waveguide along some or all of its length. The second cross-sectional shape
can be any of a large number of different conical shapes to help direct the internally
reflecting light toward the first portion where it can laterally exit the waveguide.
The first cross-sectional shape can take a variety of different forms depending
upon the illumination and other aesthetic and functional requirements for a particular
application. The surface of the first portion can be treated to control the emission
of light from that surface. The surface of the second portion can have a reflective
coating to enhance the internal reflection of light within the waveguide so that
most of the light exits laterally through the surface of the first portion. This
results in a waveguide that provides circumferentially-limited lateral light emission
along some or all of its length. The waveguide can include longitudinally-extending
flanges for mounting of the waveguide. The waveguide so constructed is particularly
suited for automotive interior and exterior lighting applications.
