| 摘要 |
An optical deflector comprises an aspheric deflecting lens (1, 13) of positive optical power. The deflecting lens (1, 13) has a first relatively short focal length giving rise to a first focal point (3) and a second relatively long focal length giving rise to a second focal point (5). Thus, a divergent beam (7) of light substantially at one of the first and second focal points is focussed by the lens at the other of the first and second focal points. Means (19), such as an electric motor, is provided for rotating the lens about an axis substantially coincident with one of the first and second focal points.
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