Servo-actuated limited-rotation motors provide an effective solution in many applications that require laser or infrared beam scanning. Early designs used moving iron rotors. The advent of rare-earth magnet materials has made possible the creation of a new type of scanner in which the rotor is a moving magnet. This paper describes the dynamic behavior, thermal characteristics, and scanning errors of this device. Comparisons made with the prior moving iron technology show moving magnet scanners to have much greater speed and accuracy. The discussion includes the effect of servo design and signal conditioning on scanning accuracy, as well as techniques for the measurement of very small dynamic scanning errors.