Digital closed-loop nanopositioning using rectilinear flexure stage and laser interferometry

To enhance the accuracy of nanopositioning and the metrological capability of scanning probe microscopy, we construct a two-dimensional interferometric nanopositioning system consisting of rectilinear flexure stage, calibrated laser interferometer, and digital feedback control system. We implement a correlation matrix, determined by the piezoelectric constant and the crosstalk between two axes, into the closed-loop control algorithm to compensate the nonlinearity and the crosstalk of the PZT-driven stage. In the tests on nanopositioning, the 1-nm-step motion and the tracking along a 1-nm-radius circular target path are accomplished to verify the short-term repeatability and the subnanometer-level precision. Additionally, a scanning tunneling microscope equipped with the interferometric nanopositioning system is built up to demonstrate the metrological functions of scanning probe microscopy.