A four-degree-of-freedom laser measurement system (FDMS) using a single-mode fiber-coupled laser module

A simple and novel method for measuring four-degree-of-freedom geometric errors of a linear stage was put forward. A single-mode fiber-coupled laser module was used. Only a cube corner retro-reflector and a beam splitter were adopted in the moving target in order to sense the straightness errors and angular errors, respectively. In this way, the horizontal and vertical straightness errors as well as yaw and pitch errors can be measured simultaneously. Theoretic error separation has been analyzed in detail and the straightness-compensated method was given. The system based on the above method was developed. In comparison with an API five-dimensional laser measurement system, the accuracy of the measuring straightness error is about ±2.5 μm within the measuring range of ±500 μm, and the angular errors are about ±3 arcsec within the range of ±400 arcsec. In addition, there is no cable connection in the moving target, which is a great convenience for the workshop measurements.