Stabilized Stroboscopic Full-Field Interferometer for Characterization of Subnanometer Surface Vibrations

The ongoing rapid development of digital camera technology together with increasing computing power enabling fast image analysis has opened up possibilities to further advance the performance of full-field interferometry. We present a software-based stabilization method for stroboscopic homodyne full-field interferometry that enables phase sensitive absolute-amplitude measurements of surface vibrations in microelectromechanical devices. The reference signal for the stabilization is obtained from a freely selectable region in the acquired interference images, resulting in a compact interferometer design without the need for additional optical components for monitoring the operation point. The proposed stabilization method is implemented in an LED-based stroboscopic Michelson-type full-field interferometer. To demonstrate the performance of the setup, an out-of-plane vibration field at 12 MHz in a square-plate silicon resonator is characterized. The data analysis reveals that a minimum detectable amplitude of less than 30 pm is achieved in the measurement. These first results already demonstrate the potential of the software-stabilization concept and serve to advance the detection of low-amplitude surface vibrations with full-field interferometry.