Wide range straightness measuring stem using a polarized multiplexed interferometer and centered shift measurement of beam polarization components

摘要

A wide range straightness measuring system of the present invention accurately determines lateral and angular displacement of a probe carriage of a cartesian robot. The system includes a laser aligned with an x-axis rail of the cartesian robot system which generates a laser beam having two polarization components. A pentaprism beamsplitter is disposed on an x-axis carriage aligned with the laser. The beamsplitter orthogonally splits the laser beam into an x-axis reference beam and a y-axis reference beam. An x-axis interferometer receives the x-axis reference beam and determines a relative position value of the probe carriage measured along the x-axis. A y-axis interferometer receives the y-axis reference beam and determines a relative position value for the probe carriage measured along the y-axis. A beam monitor receives a polarized multiplexed output of the y-axis interferometer and monitors the lateral shift of the energy centroids of the beam polarization components. Both lateral and angular displacement values of the x and y-axis reference beams can be obtained by measuring the magnitude of the lateral shift.