Critical infrastructure such as transport networks are the lifelines of modern society. Extreme weather events may cause damage to railway tracks, roads, tunnels and bridges. The Fraunhofer Institute for Physical Measurement Techniques (IPM) has developed a fast laser scanner that can be used to closely monitor transport infrastructure and plan maintenance work in a timely manner. The multispectral sensor system measures surface structures as well as the surface moisture on objects, all in a single inspection process.
From an article in Metrology News.
Winter storms, heavy rainfall and floods can cause significant damage to railway networks and roads. Detecting cracks and other defects in road surfaces, tunnel walls and other essential infrastructure is crucial – and one way to do this is by using surveying vehicles with non-contact, high-precision mobile laser scanners that can map their surroundings in three dimensions. Researchers from Fraunhofer IPM in Germany have developed a tunnel inspection system (TIS) that works with two different laser wavelengths. As well as capturing the geometry of the tunnel, bridge or other structure, this system also stands out for its unique ability to measure surface moisture.
The TIS can determine whether the interior wall of a tunnel is dry or damp, for example, thereby providing vital clues as to the tunnel’s structural health. Unlike camera-based methods, the TIS also works in adverse lighting conditions. As well as tunnels, the scanner can also assess the structural health of roads and railways. The geo-referenced 3D data it produces can be automatically evaluated.
Fastest Laser Scanner in the World
The TIS can detect defects as small as a few millimeters. “Mounted on the surveying vehicle, the scanner scans the structure at a speed of up to 80 kilometers an hour, measuring its overall geometry and – during subsequent inspections – any changes in this geometry,” says Professor Alexander Reiterer, a scientist at Fraunhofer IPM.
The system captures two million measurement points a second – in other words, the measuring beam covers the distance between the TIS and the object it is measuring, such as a wall, two million times a second. A rotating mirror is used to deflect the measurement beam in a 360-degree radius 200 times a second, ensuring blanket coverage of the object under inspection. This makes it the fastest scanner of its kind in the world. It can measure distances of up to 80 meters, which is more than enough for its purpose.
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