Portable laser scanners are typically arm-mounted or completely stationary. They are capable of collecting many thousands of points per second but lose accuracy either through the seven axes of movement in the arm or the process of building a 3-D picture from separate "shots" from a stationary camera. The system is programmed to use only one of its three axes of movement at any time in a controlled manner. This way it can collect 3-D data in a single scanning session with CMM levels of accuracy. All measurements are automatically transformed into a common coordinate system in Geomagic software, meaning that there are no patches of data to be sewn together after scanning has taken place.
Generally, the new laser scanner should be used on components shorter than 12 inches such as turbine blades that require measurement accuracy better than 0.001 inch, particularly where there is a benefit from automation. This means that precision-machined parts might make suitable applications. If larger sheet metal, clay or foam components need to be scanned, particularly on a one-off basis, an arm-based scanner is a better choice. The typical accuracy of the best arm-based scanners, 0.001 to 0.002 inch, makes them ideal for applications such as automotive styling.
The scanner's HD sensor has a two-axis servo-controlled swivel head that is integrated with a turntable. Movement of these three axes is programmable, allowing automation of measurement strategies. The key to the system's accuracy is that it uses only one servo and rotary encoder at any one time and these components are manufactured to the highest specification available. "By minimizing the opportunities for error to be introduced, the highest level of accuracy can be achieved," says Giles Gaskell, director of business development for NVision.
Before scanning and during the measurement process, the new laser scanner continually senses the object's surface and ambient light conditions and automatically adjusts the sensor to obtain the best possible measurements. True 3-D data is collected in a single data set in Geomagic software because the scanner moves around the object it scans.
The system connects easily to a standard notebook computer via USB or Firewire. The new scanner comes integrated with Geomagic computer-aided inspection software that automatically processes scan data from a physical part to generate highly accurate polygon and parametric surface models. This software also provides easy-to-understand graphical comparisons between computer-aided design models and as-built parts.
-The new laser scanner should be used on components shorter than 12 inches such as turbine blades that require measurement accuracy better than 0.001 inch.
-The sensor can be moved manually or automatically controlled to follow a predefined measurement strategy.
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