Reduction of non-orthogonality effect in nanometrology system by modified optics and signal conditioner

Misalignment and deviation angle in the optical interferometer directly decrease the accuracy of nanometrology system by producing a periodic nonlinearity error. In this paper, the effect of non-orthogonally polarized beams on the displacement measurement error in the advanced nanometrology system is presented. A system for reduction of non-orthogonality effect including linear polarizer, half-wave plate and modified signal conditioner, based on the nonlinearity compensation in a two-mode laser interferometer, is also proposed. The simulations results confirm that the peak error in the nano-displacement measurement is considerably decreased from 0.89 nm to 15 pm by using the modified optics and signal conditioner.