T•SIGHT 5000 Clearance Gauge Measurement sub-system, uses CMOS Camera Link cameras mounted in front of anamorphic mirrors custom-designed by MERMEC. These mirrors deflect the impinging reflected laser light from the walls of the tunnel orthogonally into the camera lens, allowing a line profile from the complete 360° circumference of the FOV to be captured by the cameras.
The image data are then transferred over the Camera Link interface to a Camera Link frame grabber that is situated in the cabin of the train. Here the individual line profiles are analyzed using a multicore CPU, the distance information computed, and a 3-D map of the tunnel wall recreated.
Acquiring image data at 1000 gauge profiles per second, the azimuthal image resolution obtained can vary from 2–10 mm depending on the clearance distance.
The second optical tunnel inspection system in the T•SIGHT 5000 is used to capture image data at a higher resolution so any cracks or objects within the tunnel can be more accurately analyzed.
The system also employs linescan cameras that are mounted along the axis of the system. To capture linescan image data, five mirrors mounted at 45° in the optical axis capture the reflected light from the laser illumination. In this way, a complete 360° circumference of the FOV is captured. The data are transferred over the Camera Link interface to another multicore CPU in the cabin of the train. Here again, frame grabbers are used to capture data from all cameras and transfer the whole lot into the host memory of the CPU. The linescan camera data are buffered and a linescan profile of the inside of the tunnel wall recreated.
The sampling step in the running direction of the train will depend on the speed of the vehicle, while the azimuthal image resolution will remain between 0.5 mm/pixel and 3 mm/pixel, depending on the tunnel wall distance.
