| 摘要 |
The present invention provides an optical waveguide, comprising: an input end for receiving a divergent beam; an output end for outputting an illuminating beam; a longitudinal cavity extending from the input end till the output end; a first pinhole located at a first predetermined distance from the input end within the said longitudinal cavity for receiving the divergent beam and for generating a fringe pattern, said first pinhole bifurcating the longitudinal cavity into a first and a second light propagating regions, the longitudinal cavity forming the first light propagating region being provided with a reflective coating on its internal surface to enable internal reflection of the divergent beam; and a second pinhole located at the output end for receiving the fringe pattern thus generated by the first pinhole and for outputting the illuminating beam corresponding to a central bright fringe contained in the said fringe pattern via the output end.
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