Process and apparatus for three-dimensional surveying
First Claim
1. A process of three-dimensional surveying in which a scene is scanned by emitting a laser beam in its direction, the image of the laser spot obtained in this way being formed on at least one element of an array of photoresistive receptor elements, the direction of the laser spot relative to the said array being determined from the position of the exited receptor element in said array of elements, and the three spatial coordinates of each point of scanning being calculated by triangulation on the basis of the angular orientation of the beam emitted and the said direction of the reflected spot received, characterized by the fact that(a) the scene is scanned by controllably orienting the beam relatively roughly,(b) the orientation of the beam emitted being measured more precisely independently of the controllable orientation thereof, and(c) that the said spatial coordinates are calculated on the basis of the independently measured orientation of the beam emitted and the said direction of the spot.
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Accused Products
Abstract
The invention relates to process and apparatus for three-dimensional surveying by triangulation with a laser beam source. Pursuant to known practice, a laser beam scans a scene to be surveyed, by means of controlled rotary positioning of a mirror. The reflected beam is detected by a linear array of photosensitive receptors, enabling the location of the illuminated point to be determined by triangulation. Significant to the invention is the use of a secondary light source for precision measurement of the angular location of the scanning mirror, rather than relying upon controlled positioning of the mirror, which is much less accurate.
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Citations
12 Claims
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1. A process of three-dimensional surveying in which a scene is scanned by emitting a laser beam in its direction, the image of the laser spot obtained in this way being formed on at least one element of an array of photoresistive receptor elements, the direction of the laser spot relative to the said array being determined from the position of the exited receptor element in said array of elements, and the three spatial coordinates of each point of scanning being calculated by triangulation on the basis of the angular orientation of the beam emitted and the said direction of the reflected spot received, characterized by the fact that
(a) the scene is scanned by controllably orienting the beam relatively roughly, (b) the orientation of the beam emitted being measured more precisely independently of the controllable orientation thereof, and (c) that the said spatial coordinates are calculated on the basis of the independently measured orientation of the beam emitted and the said direction of the spot.
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4. An apparatus for three-dimensional surveying of a scene, comprised of a laser emitter, a rotationally movable scanning device for scanning the scene using the beam emitted by the laser, and a first photosensitive receptor means adapted to form an image of the spot created by the laser beam on the scene, characterized by
(a) means for controllably orienting said emitted beam, and (b) independent means for measuring the orientation of the beam at the exit of the scanning device.
Specification