Advanced laser telemetry for vehicle monitoring and other industrial applications

The need to prevent train accidents inside railway tunnels has motivated the national railway Company Ferrovie dello Stato to launch a project aimed at installing a number of train monitoring portals at a suitable distance from the tunnel entrances. The first experimental portal, and a second operative one, have been installed by SIRTI S.p.A., respectively in Rastignano and Formia. Our company, in collaboration with the Laboratory of Optoelectronics of the University of Brescia, have been requested to develop all the multisensor architecture for the dimensional and thermal monitoring of the trains to be installed on the portals. One of the key elements of the portal is the shape acquisition sensor, based on scanning telemetry. In the second portal, based on the experience gathered from the first one, a novel shape acquisition system based on time-of-flight telemeters has been developed. This telemeter has been specifically designed for the high-speed, high-resolution monitoring of trains in railway portals, but can be adapted to a number of industrial and environmental applications. The system uses a single transmitter/receiver unit to feed, using optical fibre pairs, a number of measuring stations. It makes use of an ultrashort fibre laser operating at 400 kHz or alternatively a fibre-couple diode laser, and presents in-house developed solutions to obtain a 40 dB dynamic range, thus allowing to monitor targets within large distance/angle/colour intervals. The system has been developed, tested and installed on a train-monitoring portal in the Rome-Neaples railway.