Confocal Laser Vibrometry

Abstract

AbstractWith laser interferometry vibrations can be measured with picometer resolution. A prerequisite for such measurements is that the sample is optically accessible for the measurement laser. However, because MEMS sensors are increasingly designed with multiple layers and are encapsulated in silicon packages, their vibrations are often out of reach for conventional laser vibrometers. Here we show that with a smart combination of scanning microscopy and laser interferometry it is now possible to measure vibrations within encapsulated MEMS devices.