| abstract |
The index of refraction of a light guide ( 6 ) for transmitting light outputted from a primary light source ( 1 ) is ng, and the light guide ( 6 ) has a light input end face ( 9 ), a light output surface from which the transmitted light is outputted, and a back surface opposed to the light output surface. A leaky ray modulator ( 8 ) is provided to at least either the light output surface or the back surface. The leaky ray modulator ( 8 ) has a composite layer ( 50 ) provided on the light output surface or the back surface and composed of first refractive index regions ( 3 ) having a refractive index n 1 (ng>n 1 ) and second refractive index regions ( 4 ) having a refractive index n 2 (n 2 >n 1 ) and a third refractive index layer ( 5 ) provided on the composite layer ( 50 ) and having a refractive index n 3 (n 3 >n 1 ). A reflecting plate ( 7 ) is provided adjacent to the back surface of the light guide ( 6 ). |