A cyclic aperture flow regulator system has an adjustable fluid aperture in a fluid path connecting the aspiration port of a surgical probe with a vacuum source. The cross-sectional area of the fluid aperture can be modified by an actuator. The actuator is controlled to modify the cross-sectional area of the adjustable fluid aperture in cycles. During each cycle, the fluid aperture cross-sectional area is substantially reduced or closed. The cycles occur at a rate fast enough to produce a substantially steady flow, with minimum flow ripple and pressure ripple.