摘要 |
A method for determining the relative motion of a surface with respect to a measurement device including placing a partially transmitting object, which is part of the measuring device, adjacent to the surface; illuminating the surface with incident illumination, which does not constitute an interference pattern, such that the illumination is reflected from portions of the surface, wherein at least part of at least one of the incident and reflected illumination passes through the object; detecting the illumination reflected from the surface, and generating a detected signal; and determining the relative motion of the surface parallel to the surface, from the detected signal.
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