Scanning Arms
In addition to highly accurate tactile measurements using 7-axis measuring arms, scanning arms provide fast and precise 3D laser scanning. This makes them multifunctional metrology systems capable of covering a wide range of measurement tasks. Scanning arms enable the contact-free measurement of large surfaces in a very short time. When combined with tactile probing, geometric features and point clouds can be captured in parallel with high precision.
MEASUREMENT VOLUME & ACCURACY
As with portable measuring arms, the measurement volume is limited by the physical reach of the arm itself. Typically, volumes with diameters between 2.0 m and 4.5 m can be measured. When combined with a laser tracker, this volume can be extended almost without limit. Depending on the size of the arm, achievable accuracies range from 0.05 mm to 0.14 mm.
SETUP & SPEED
The scanning unit is mounted directly onto the measuring arm, which is positioned on either a magnetic base or a tripod. A major advantage of scanning arms is their extremely high data acquisition rate: more than 100,000 points per second. This enables large surfaces to be measured in a very short time while capturing even the smallest details with high resolution.
HOW IT WORKS
The spatial position of the line scanner is determined—just like with a measuring arm—by the positions of the seven joints. The line scanner itself is an integrated optical sensor consisting of a laser light source and an electronic image sensor. The laser beam is typically expanded into a line and projected onto the object surface, where it is scattered. A camera, usually a CCD or CMOS sensor, is equipped with an optical band-pass filter to suppress ambient light. The camera is positioned at an angle relative to the laser line and detects the scattered light. Depending on the distance between the object and the laser source, the position of the laser line shifts on the camera sensor. Using triangulation, the system calculates the 3D coordinates of each individual measurement point.
