A 400-kHz High-Accuracy Laser Telemeter for Distributed Measurements of 3-D Profiles

A distributed telemeter is herein presented, which has specifically been 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 fiber pairs, a number of measuring stations. It makes use of an ultrashort fiber laser operating at 400 kHz or, alternatively, a fiber-coupled diode laser and presents in-house developed solutions to obtain a 40-dB dynamic range, thus allowing to monitor targets within large distance/angle/color intervals. The system has been developed, tested, and installed on a train-monitoring portal in the Roma-Napoli railway, in the framework of an effort to increase the safety of trains entering tunnels in the Italian railway system.