Correction of Nonlinearity in High-Resolution Nano-Displacement Measurements

In this paper, a simple method to reduce the nonlinearity in the high-resolution nano-displacement measuring system using a modified laser interferometer is presented. By using a retarder plate and improved optical head, in additional to the nonlinearity compensation, the resolution of the displacement measurement is doubled and quadrupled compared to the conventional three- and two-mode laser interferometers, respectively. In the particular case, the nonlinearity of 18.4 nm is reduced to a value of 140 pm.