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Three-dimensional lasers

01 Jan 2007

Laser profile sensors are being employed in Russia by Infotrans to measure track wear. The sensors, developed by Micro-Epsilon, are used on Infotrans' inspection train to assess the state of RZD's track. The sensors build on existing track measurement technology by enabling profiling at speed as the inspection train passes.

Micro-Epsilon's LLT 2800-100 sensors are designed to overcome the difficulty of enabling laser sensors to attain a sufficiently high resolution for accurate measurements to be taken from the train. Laser scanning is also often hampered by the differing reflective qualities of the rails, with extremely shiny or excessively corroded railheads making accurate scans impossible.

The LLT 2800-100 design uses an integrated CMOS array to facilitate measurement of shiny, reflective or transparent surfaces. A line optical system projects a laser line onto the surface of the rail and the back-scattered light from the laser line is registered on the CMOS matrix. Using both z-axis distance information and the position along the laser line from the camera image, a traversing sensor generates a three-dimensional representation of the track profile to determine wear.

The sensors used by Infotrans are designed for use at speeds of between 120 and 130 km/h. Each sensor has a 50 mW laser with a 4 kHz frequency, allowing up to 4 000 profiles to be measured per second.

Micro-Epsilon, UK