Miniature three-axis micropositioner for scanning proximal probe and other applications

A small, 2X2X1.1 cm (height), three-axis micropositioner has been developed. It combines sub-nm positioning capability with a large range of travel of more than 1 mm in each direction. Its applications range from scanning proximal probe instruments to sample stages for electron or light microscopes. Two shear piezos are provided in each direction to facilitate motion. They are located at opposite sides of a moving frame which is guided by V grooves on sapphire balls (or rods). A critical point in designing this kind of positioners is how to generate the ''attachment'' force that holds the parts of the positioner together. Gravity cannot be used as the stage needs to work in all orientations. Springs, connecting the two parts moving relative to each other, generate a force in the direction of the desired motion that is changing with position, making the stage motion nonlinear. Magnets are not appropriate when low-energy electrons are involved in the vicinity. This problem is solved by especially designed leaf springs coupled to V grooves and balls (or rods). This design allows the attachment force to remain constant and orthogonal to the direction of motion when the stage moves, thus making the motion very linear and independent of the orientation of the positioner. The positioner is exceptionally compact and can be operated in ultrahigh vacuum. These properties make the positioner attractive for atomic scale resolution scanning proximal probe microscopes and a wide range of other applications. (C) 1995 American Vacuum Society.