Optical characterization of micro and nanomechanical systems in two dimensions

A simple optical setup combining interferometric and knife-edge methods is proposed for deflection measurements and sensing both out-of-plane and in-plane movements of MEMS and NEMS devices. The setup has 100 pm/√Hz in-plane measurement resolution for 1 μm full-width-half-maximum spot size illumination and 4 pm/√Hz out-of-plane resolution. The sensor offers large dynamic range. Sensor setup can also be used to measure and differentiate combined modes in some cases.