Speed Measuring System

The non-contact speed measuring systems make use of the Doppler effect, describing the speed-dependent frequency shift of a wave (diffuse reflection of light) reflected from a moving object (strip, foil).

In principle, there are two variants of such laser Doppler velocimeters:

• The first group uses the reflected signal of two lasers, radiating onto the strip in a defined angle, thus producing a line pattern. The line distance is in proportion to the speed.
• Alternatively available units are working with incandescent light, resp. LED light source. These velocimeters use the Doppler modulation of latticed structures onto the strip surface for measuring the strip speed.