| 摘要 |
A device and method for speckle reduction are disclosed, wherein a coherent laser beam (3) is expanded by using a beam expander (7). The expanded beam is subsequently allowed to pass through a variable optical element (11), which may comprise a liquid crystal cell, and applies a diffractive function on the expanded beam. The cross-section of the beam is then reduced by means of a collimator (17). The speckle pattern of the collimated beam is varied quickly, such that the extent of annoying speckle, which is perceived when the beam is projected on a surface, is reduced.
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