A straightness measurement system using a single-mode fiber-coupled laser module

In this paper, a quite simple and novel straightness measurement system is proposed. The laser beam from a single-mode fiber-coupled laser module is highly stable, and can be used as the reference line for straightness measurements of any mechanical system. A corner retro-reflector is used as the moving target in the system in order to sense the straightness error and to reflect laser beam from measurement head back to it. In this way, there is no cable connection in the moving target, which is necessary for straightness measurements in workshop. At the same time, relationship between voltage output from a quadrant photodiode detector and its displacement was analyzed, and the theoretical analysis shows a good consistence with practical measurement results, which gives a way to enlarge the measurement range of the system. Comparative results of straightness measurement with a dual frequency laser interferometer were given, and repeatability with one micrometer at the distance of 1 m was gotten by the system.