A novel method to enhance the sensitivity for two-degrees-of-freedom straightness measurement

A low cost and high precision system which can measure two-degrees-of-freedom straightness simultaneously is proposed based on a laser collimator. In the system, a miniature fiber coupled diode laser generates a collimating beam. The sensitivity of the straightness error measurement is magnified by a factor of 4 compared with the lateral movement of the retro-reflector itself after the multi-reflections. A Renishaw ML10 laser interference measurement system was used to verify the developed system in a series of experiments in the laboratory environment. Experimental results agree with the expected results. The two-dimensional straightness error measurement had linear correlativity close to 1 and the standard one-to-one deviation error was better than 0.32 mu m obtained over a travel range of 600 mu m.