| 摘要 |
<p>A fan beam of light from a source (L) is directed across the edge of a car body window frame section (10) with an external reflective corner (11) and an internal reflective corner (12). The corners reflect sharp spots of light (S1) and (S2) respectively into a detector (D) which produces an output waveform (Fig. 2) in which sharp pulses (P1, P2) correspond to the spots of light. It is easy to discriminate against other pulses (P3) arising from stray reflections, e.g. the multiple reflection (I3, R3). The positions of the pulses (P1 and P2) enable the positions of the corners to be calculated. Two detectors and/or two light sources may be used to incrase the amount of data available so as to allow a complete solution for the coordinates of the centres of curvature (C1, C2) of the corners relative to the detectors and the radii of curvature of the corners.</p> |
