Patent ID: 7120325

Claim:
An optical waveguide apparatus comprising: a sheet-shaped optical waveguide capable of propagating light in two-dimensional directions; a light emitting unit configured and positioned to emit at least two light beams in different directions to said waveguide; light receiving units for receiving light propagating in said waveguide; at least two light diffusing structures each of which diffuses one of the light beams emitted from said light emitting unit, wherein said light emitting unit emits the at least two light beams in different directions within said waveguide so that each light beam is directed toward and received by a different light diffusing structure; and a closed region having said light receiving units, wherein each of said light diffusing structures is located closer to one of the light receiving units than said emitting unit in said closed region, wherein each light beam emitted by said light emitting unit propagates to and is diffused in said closed region by one of said light diffusing structures to propagate in all directions therefrom within the closed region, and said light receiving units are located at positions that surround said at least two light diffusion structures within the closed region to receive the light diffused by said at least two light diffusing structures.