Two-wavelength Grating Interferometry for Extended Range MEMS Metrology

Abstract

Diffraction gratings integrated with MEMS has many applications as they can offer shot noise limited sub-nm displacement detection sensitivities but are limited in range. A two-wavelength readout method is developed that maintains high sensitivity while increasing the detection range from 105 nm to 1.7 um assuming sensitivity is maintained at >50% of the maximum sensitivity.