Development of an optical measuring system for geometric errors of a miniaturized machine tool

Recently, miniaturized machine tools (mMT) have become a promising micro/meso-mechanical manufacturing technique to overcome the material limitation and produce complex 3D meso-scale components with higher accuracy. To achieve sub-micron accuracy, geometric errors of a miniaturized machine tool should be identified and compensated. An optic multi-degree-of-freedom (DOF) measuring system, composed of one laser diode, two beam splitters and three position sensing detectors(PSDs), is proposed for simultaneous measurement of horizontal straightness, vertical straightness, pitch, yaw and roll errors along a moving axis of mMT. Homogeneous transformation matrix (HTM) is used to derive the relationship between the readings of PSDs and geometric errors, and an error estimation algorithm is presented to calculate the geometric errors. Simulation is carried out to prove the estimation accuracy of this algorithm. In theory, the measurement resolution of this proposed system can reach up to 0.03 μm and 0.06arcsec for translational and rotational errors, respectively.