Metrology and Calibration of a Long Travel Stage

Nine axes of displacement measuring interferometers (DMIs) provide feedback for the control of a six-degree of freedom stage with a work volume of 500 × 1 × 1 mm3. Four additional DMIs are used for straightness and squareness calibration. Even with correction for angular error motions, cosine errors combined with cyclic errors compromise straightness calibration with a moving mirror configuration. A Fizeau interferometer provides pitch and yaw measurement. Automatic cyclic error compensation is demonstrated.