| 摘要 |
An optical method and apparatus (10) for determining characteristics of an object (12), such as size, shape, position, orientation, cross-sectional area, volume, and surface topography. A laser beam (19) is reflected through a multi-faceted mirror (34), which rotates about it own axis (48) as it orbits around the object, causing a plurality of rotary scanning beams (36) to sweep across the object as the mirror orbits. Portions of the beam not blocked by the object strike a retroreflective ring (38) positioned around the object and are returned along the beam's incident path to a detector (44). By associating the corresponding orbital position and rotational orientation of the mirror with the detector signal each time a shadow is created by the object, tangents to the surface can be calculated. The tangents gathered during each orbit are assimilated to determine the cross section of the object in the plane of the orbit of the mirror. Changing the longitudinal position between the mirror and the object allows the cross section to be determined and combined to calculate the total surface topography or volume of the object.
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