Solid-state ranger also profile
Laser range scanners are based either on triangulation or time-of-flight principles. They are also relatively expensive, feature limited measurement range, and include mechanical scanning components that cannot endure shock and vibration for long periods. To overcome these limitations, Janusz Marsalec, a senior research scientist at VTT Electronics (Kaitovayla, Finland) has developed a solid-state sensor for 3-D shape measurement that uses no moving parts.
Constructed of two modules, a transmitter and receiver, the scanner uses a 13-mm-long arrangement of 32 infrared LEDs as its light source. The receiver includes focusing optics and a 1-D position-sensing detector. Both transmitter and receiver are controlled by a computer that supervises the sequential scanning and speed of scan.
During a scan, one LED of the light source is activated at a time, and the emitted radiation is collimated by the lens into a narrow beam. The position of the LED source in relation to the optical axis of the optics determines the direction of the beam. When this light spot is reflected from the target surface and detected, its position on the detector`s surface provides the angle of the reflected beam. The distance of the object is then computed by triangulation.
By activating another LED from the source array, the measuring direction can be changed and the distance to another point of the reflecting surface can be measured. A full scan is performed by multiplexing all of the sources of the LED array. The result is a set of distances and directions that is used to provide shape and profile measurements of the object being scanned. For more information contact Janusz.Marsalec@vtt.fi.