| 摘要 |
A pointing device having an illumination system, camera system, and positioning mechanism is disclosed. The illumination system illuminates a surface below a transparent plate having a constant thickness. The camera system records images of the illuminated surface. The positioning mechanism adjusts the relative position of the illumination with respect to the camera system. The relative position is determined by the constant thickness. The positioning mechanism has a first position corresponding to a predetermined value for the constant thickness and a second position corresponding to the constant thickness being zero. The positioning mechanism is operable by a user of the pointing device to compensate for different thicknesses of transparent plates.
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