| 摘要 |
A scanning device for capturing images, which contains an optical unit comprising a light source (3), a light guide (2), and a light receiver (5). The light guide (2) comprises a substantially parallel sided, transparent member, the member having first opposed ends (10, 13) extending between the parallel sides (11, 12), one of the ends (10) facing the light source and extending non-orthogonally between the parallel sides, the other end (13) facing the image to be scanned in use, and second opposed ends (14, 15) extending between the parallel sides and the first opposed ends. Light from the light source (3) enters the light guide through the one first end (10), is directed onto the image after passing out of the other first end (13), is reflected back into the light guide and then directed by the light guide towards the light receiver (5). The arrangement is such that one portion of the reflected light passes to the light receiver (5) without being reflected by the second opposed ends while another portion of the reflected light passes to the light receiver after being reflected by one or both of the second opposed ends, the two portions being directed to different parts of the light receiver, the device further comprising a filter through which one of the light portions passes while the other does not. |
