Feedback controlled nano-positioner using fiber optic EFPI sensor with novel demodulation technique

For the translation stage of nanometer scale, fiber optic EFPI sensor is suggested for the feedback control system on account of its high sensitivity, small size, simple system and relatively low cost. The novel signal processing algorithm for the real-time demodulation of EFPI output signal was developed and verified. The local linearity in the adjacent fringe values was shown, and used for the sinusoidal approximation of the nonlinear output signal. The real-time signal processing program was designed and the intensity signal of the EFPI sensor was demodulated to the phase shift with this program. The theoretical resolution of 0.36-8.6 nm in the displacement range of 0-200 μm was obtained The sensor system was applied to the 1-D nano-positioner with a Piezo-electric actuator. The positioner successfully reached to the desired destination within 1 nm accuracy.