Real-time vibration amplitude and phase imagingwith heterodyne interferometry and correlation image sensor

摘要

We propose a new out-of-plane vibration imaging technique for micro-structured solid-state devices such asMEMS (micro-electro mechanical systems) microphones or resonators. The technique is based on the longitudi-nally scanning optical interferometry and an integrated image sensor device which we call the correlation imagesensor (CIS). The CIS is able to extract an arbitrary frequency component from time-varying incident light andproduce a complex correlation image including amplitude and phase in addition to a conventional intensity im-age. In heterodyne interferometry of vibrating objects, the vibration information is encoded in several frequencycomponents generated by mutual modulation of longitudinal scan and vibration. In this paper, combinationof newly developed multi-channel CIS and the scanning heterodyne technique enable us to obtain the multi-ple frequency components simultaneously and reconstruct the vibration amplitude and phase distributions inreal-time. As an example, vibration modes of a MEMS acoustic sensor are shown to be reconstructed at videorate. A theoretical possibility for the imaging of higher than GHz vibration combining other optical heterodynetechniques is also discussed.