Development of biaxial active vibration suppression system with piezoelectric inertial actuator for electron microscope

Abstract

Active vibration suppression should have high performance and has been studied and applied over the years. However, its practical applications are limited to large objects due to its implementation cost or design man-hour. In previous study, we proposed a distributed general-purpose active vibration suppression system which can be applied to various relatively small-size equipment with add-on style. Additionally we have developed a network distributed controller which have I/O number scalability. In this paper, the development of the active vibration suppression system for electron microscope is described as an application example. The electron microscope is an inspection device which observes sample with an electron beam irradiated from the top of its column. This column has two inclining modes which, when affected by vibration, cause image blur. Therefore, to avoid their vibration, a biaxial vibration suppression system which damps two inclining modes was developed. In this process, first, an inertial actuator using multilayer piezoelectric devices was developed as the damping actuator, and its characteristics were investigated. Then, the biaxial active vibration suppression system was constructed with the actuators for a dummy column, which had two inclining modes and was able to reproduce the vibration characteristics of the electron microscope. Finally, a controller with two inputs and two outputs was designed for the biaxial active vibration system. Evaluation of the vibration damping performance showed that both modes were damped in more than 15 dB.

Keywords

• vibration control
• active vibration suppression
• piezoelectric element
• accelerometer
• electron microscope