Measurement of four-degree-of-freedom error motions based on non-diffracting beam

A measuring method for the determination of error motions of linear stages based on non-diffracting beams (NDB) is presented. A right-angle prism and a beam splitter are adopted as the measuring head, which is fixed on the moving stage in order to sense the straightness and angular errors. Two CCDs are used to capture the NDB patterns that are carrying the errors. Four different types errors, the vertical straightness error and three rotational errors (the pitch, roll and yaw errors), can be separated and distinguished through theoretical analysis of the shift in the centre positions in the two cameras. Simulation results show that the proposed method using NDB can measure four-degrees-of-freedom errors for the linear stage. •Error motions of a linear stage directly influence the performance of the precision positioning system in which the stage is used.•Therefore, it is a critical task to measure the error motions.•In this paper, a measurement method of four-degree-of-freedom error motions based on non-diffracting beams that has the characteristics that the center form can remained unchanged in a long distance is presented.•A right-angle prism and a beam splitter are combined together and are regarded as the measuring head, fixed on the moving stage in order to sense the straightness error and angular errors.•The presented system can measure the vertical straightness error and three rotational errors (the pitch error, roll error and yaw error), and these four different type errors can be separated and distinguished through analyzing the shift of the center positions in the two cameras.•The theoretical analysis and simulation results show that this measurement method is valuable in the errors measurement of linear stage.