An ultra-sensitive optical angle sensor for pitch deviation measurement of diffraction gratings

A new method using an ultra-sensitive angle sensor to evaluate the grating pitch deviation is proposed in this paper. The principle and theoretical calculation are done to confirm the theoretical feasibility of the new proposed method. Theoretically, with a high resolution optical angle sensor, this method can reach an extremely high resolution of picometers for the evaluation of grating pitch deviation. Compensation methods of angle error during scanning process are also discussed.