Published online by Cambridge University Press: 14 November 2012
In order to achieve nanometer accuracy, metrologists need to identify the sources oferror and develop solutions to eradicate or minimize their effects. A stabilized low powerdual-frequency laser heterodyne interferometer (ZMI-1000A) designed to measure linear andangular displacement with nominal measurement resolution 1.24 nm and 0.0025 arcsec,respectively, is used to achieve measurement of displacements over different travellingaxes by comparison with the electronically reference measurements of the stage over widerange 500 mm. The repeatability and reversal error of linear stage over the workingdistance have agreed opto-electronically and the positioning uncertainty been reduced. Amultivariable framework was implemented for the x-axis due to the crosscoupling between the forward and backward course of the linear stage. Thermal errorreduction is achieved using environmental temperature control (20 ± 0.2 °C)to help reduce thermal errors.