Study of the Method for Measuring Four-Degree-of-Freedom Geometric Errors of a Linear Stage

A novel method for measuring four-degree-of-freedom geometric errors of a linear stage is put forward.A single-mode fiber-coupled laser module is used,and the laser beam from this laser module is highly stable,and can be used as the reference line for straightness error and angular error measurements.Only a corner retro-reflector and a beam splitter are adopted in the moving target in order to sense the straightness errors and angular errors.In this way,the horizontal and vertical straightness errors as well as yaw and pitch errors can be measured simultaneously.At the same time,there is no cable connection in the moving target,which gives a great convenience in the workshop measurements.The four-degree-of-freedom measuring system(FDMS) based on the above method has been developed,and the system has the resolution of less than 0.1 micrometer for straightness error measurement and 0.5 arc-sec for angular error measurement.The stability,repeatability experiments and the comparison experiments with API 5D laser measuring system were done.Experimental results and theoretical analyses showed that the measurement accuracies of straightness error and angular errors are about ±1.0 μm/m and ±0.5″ respectively within the measurement range of 2 m.