YAG laser blasts leaves on the line

17 Jun 2002

An Nd:YAG laser attached to a train removes congealed leaves from railway tracks.

A UK company is using a YAG laser to blast leaves off of railway lines. LaserThor, with help from the Rutherford Appleton Laboratory (RAL), UK, is expecting to sell its first systems to customers next year.

In autumn, leaves falling from trees growing near railway lines get wet and are crushed underneath passing trains. The result is a shiny, black coating on the tracks that makes it difficult for the trains to brake effectively.

According to Tony Parker, head of the Lasers for Science Facility at RAL, the problem can get so bad that trains can skid on the rails and take twice as long to stop.

Parker has been working with Malcolm Higgins, who set up LaserThor after coming up with the idea of using lasers to remove the leaves.

In initial trials, the company installed an Nd:YAG laser from Spectron Laser Systems, UK, operating at 1064 nm on a train. The train's on-board generator powered the laser.

These trials showed that the leaves could be removed with the laser mounted on a train running at slow speeds. Higgins then contacted the Fraunhofer Institute for Laser Technology in Aachen, Germany, to build a compact 1 kW Nd:YAG source. This system has a higher pulse rate, uses fiber-optic beam delivery instead of mirrors and lenses, and works with the train running at more realistic speeds.

According to LaserThor, the laser can also remove oil, grease, ice and tyre rubber from tracks. More trials and demonstrations to potential customers are planned for later this year, and Higgins hopes to sell the first units in 2003.

Author
Michael Hatcher is technology editor of Opto & Laser Europe magazine.