Three-dimensional displacement measurement system based on optical free-form surface

In the displacement measurement of multi-axis systems such as computer numerical control (CNC) machine tools and multi-axis translation stages, there exist many problems. For example, the detection methods are complicated and the cost is high. Regarding these problems, full use was made of the advantages of great design freedom of optical freeform surface to simplify the system and improve system performance. A method of non-contact threedimensional displacement measurement based on an optical free-form surface was proposed to detect the accuracy of multi-axis systems such as general CNC machine tools. The optical free-form surface used as datum was designed. The experimental platform was built and the mathematical model of measurement system was established. Then, the system was calibrated and its accuracy was tested. Finally, three-dimensional displacement measurement experiments were carried out. Results show that the accuracy of the measurement system was up to 2.8 μm, and the measurement system can be applied to the three-dimensional displacement measurement of multi-axis systems.