Fundamentals:
Laser ranging using triangulation
The alternative of laser triangulation is illustrated in
Figures 9 and 10 (below).
Click here to see both images on screen at the same time
Figure 9: Schematic of a triangulation sensor
Figure 10: The geometry of triangulation sensing
A spot may be scanned in two dimensions, or alternatively a laser stripe is scanned in one dimension across the scene. Commonly, a low power laser beam is transformed by a cylindrical lens into a vertical plane, enlightening the object in the field of view. The video camera observes the object in which displacement of the line from the mid (usually) position is linearly proportional to the object
depth. Advanced commercial equipment based on his principle can now acquire dense depth images to a resolution of about 0.1mm at a working depth of the order of a metre, sometimes at video rates.
Scaled down triangulation systems can be mounted on coordinate measuring machines to give much higher resolution but with a much restricted field of interest.
[ Laser ranging using Time of Flight ]
Comments to: Sarah Price at ICBL.
(Last update: 4th July, 1996)