| 摘要 |
An image projection device includes a Fresnel lens (11) positioned in an optical path of an illuminated image (10) in such a way that light from the image passes twice through the Fresnel lens (11). A first optical element may be a planar mirror (13) arranged to reflect light transmitted by said Fresnel lens (11) in a first direction back through the Fresnel lens (11) in a second direction. A second optical element may be provided for changing a path of light exiting said Fresnel lens in the second direction so that the projected image appears at a location away from the path of light from the image source to the Fresnel lens.
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