of electrical quantities and linear displacement and velocity this is performed in two measurement steps 1 static measurement this consists of measuring the equilibrium lateral displacement of the calibration device 10 as a function of applied voltage we measure this static displacement using white light interferometry using a zygo newview 5020 interferometer zygo corporation middlefield conn 06455 0448 usa the drie etched face of the calibration device 10 is sufficiently perpendicular to the plane of motion for optical fringes to be located and measured allowing accurate measurement of static displacement 2 dynamic measurement illustrated schematically in fig2 this consists of measuring the current to earth passing through the device while simultaneously measuring its instantaneous vibration velocity using doppler velocimetry the extremely sharp resonance of the calibration device even when operating in air allows us to separate the change in capacitance of the device due to mechanical displacement from the inevitable parasitic capacitances elsewhere in the circuit the velocity of the calibration device 10 was measured edge on using a polytec opv1 doppler velocimeter polytec gmbh waldbronn germany and this signal recorded using a hp 3562a dynamic signal analyser agilent technologies palo alto calif these data were downloaded from the dynamic signal analyser to a personal computer current through the calibration device 10 was measured using a cyberamp 320 signal conditioner with type 403 preamplifier molecular devices corporation union city calif by using it in u201c virtual earth u201d configuration any parasitic capacitance across the input of the amplifier or between the moving part of the actuator and the die substrate connects virtual earth 60 to earth so its.