A cryogenic scanning stage with position control for a magnetic microscope

Abstract We describe a low-temperature mechanism used to move the sample in our scanning SQUID magnetic microscope. The movement is generated by newly developed piezoelectric actuators of the bimorph type and is amplified 8 times by a lever system to reach a total scan range of 2 mm ×2 mm . A capacitive transducer monitors the position of the scanning stage by a variable area capacitor integrating over x and y directions. The capacitance measurement is based on a null bridge with quickly responding digital feedback. The instrument controls completely the scanning stage by energizing the piezoelectric actuators, monitoring the capacitance changes and correcting the stage position accordingly.