The ABRS high-precision rotary air-bearing stages from Aerotech Inc. have a slotless zero-cogging motor and a low-profile design to reduce effective working height and to minimize stack-up errors. Designed for high-precision angular positioning and velocity stability, the stages’ high stiffness and load capacity minimize axial, radial and tilt error motion to satisfy applications requiring good planar performance. The brushless motor is inherently torque-ripple-free to maximize positioning accuracy. The stages meet the motion control requirements of semiconductor wafer inspection, high-precision metrology, x-ray diffraction, optical inspection and fabrication, and microelectromechanical systems/nanotechnology device fabrication. A direct-coupled rotary encoder achieves resolution of <0.03 arcsec and accuracy of ±1 arcsec or less when used with the unit’s feedback multipliers and controls.