Direct extraction of surface vibration profiles with optical beam deflection

We present a method and an accompanying data analysis technique that provide direct displacement information of surfaces based on optical beam deflection. This approach improves measurement accuracy by simplifying the measurement procedure and avoiding the need for optical system modeling. With calibration, the spatially dependent displacement of a surface becomes available. This method is applied to a circularly symmetric deformation of a gold-silicon nitride membrane heterostructure whose motion is excited by a modulated laser, and results are presented. The general approach is applicable to other deformation profiles with known features other than circular symmetry, making it broadly useful for characterizing the mechanical behavior of micro-scale devices and for optomechanics and mechanical metamaterial studies.