We develop a displacement measurement and positioning system with nanometer resolution over the millimeter traveling range The method is based on a heterodyne grating shearing interferometry a homemade lock-in amplifier and a servo control loop for displacement sensing and positioning The quasi-common optical path configuration of our system provides better immunity against environmental disturbances The experimental results demonstrate that our system can measure small and long displacement with nanometric resolution The device achieves a positioning resolution of 23 nm over a traveling range of 20 mm (C) 2010 Elsevier BV All rights reserved
