| 摘要 |
An optical method and apparatus are disclosed for determining characteristics of an object such as its size, shape, position, orientation, cross-sectional area, volume, surface topography and specific volume. The inventive method and apparatus utilize a laser beam which is reflected through a right angle by a multi-faceted mirror. The mirror rotates about its own axis as it orbits around the object to be measured, causing a plurality of rotary scanning beams to sweep inwardly across the object as the mirror orbits. Portions of the scanning beam that are not blocked by the object strike a retroreflective ring positioned around the object and are returned along the beam's incident path to a detector. 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 of the object can be calculated. The tangents gathered during each orbit can then be assimilated to determine the cross-section of the object in the plane of the mirror's orbit. Changing the relative longitudinal position between the orbiting mirror and the object allows successive cross-sections to be determined and combined to calculate the total surface topography or volume of the object. |
