Distributed laser telemeter for profile measurement

The paper describes an innovative distributed laser telemeter for the contactless acquisition of the profile of objects. The system uses a single laser source (presently a subnanosecond fibre laser and/or a nanosecond diode laser), to feed, in a time-multiplexed way, several measuring stations (presently four) through the use of fiberoptics beam splitters and an optical switch. The optical signals diffused by the targets are in turn combined by other fiberoptics, and feed a single, fast time-of-flight APD/TDC measuring unit. The distributed telemeter is highly innovative with respect to the existing single-target telemeters, and is especially intended for multi-target monitoring while maintaining low system costs and minimizing maintenance requirements. The key performance of the telemeter are a measuring range of 0,5-15m, a resolution of 2mm, and a measuring frequency up to 1 MHz. The system has been developed in the framework of the Q-Tech development of a multifunction portal for the monitoring of trains in railway, but can be easily adapted to all measuring applications where many targets should be measured at the same time by a single source-detector combination.