| 摘要 |
A pointing device includes a light source, an aperture member, and a detector. The light source provides incident light for illuminating an obverse surface of a plate at a predetermined incident angle. The plate has the obverse surface and a reverse surface and is transparent to the wavelength of the incident light. The aperture member has an opening through which speckle light from the obverse surface and speckle light from the reverse surface pass. The speckle light results from the incident light. The detector detects the intensity of the speckle light passing through the opening. In order that the speckle light from the obverse surface and the speckle light from the reverse surface overlap each other at the detector, the opening has a longitudinal dimension in a direction in which the incident angle is formed.
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