Substrate support apparatus and methods are described. Motion of a substrate chuck relative to a stage mirror may be dynamically compensated by sensing a displacement of the substrate chuck relative to the stage mirror and coupling a signal proportional to the displacement in one or more feedback loops with Z stage actuators and/or XY stage actuators coupled to the stage mirror. Alternatively, a substrate support apparatus may include a Z stage plate a stage mirror, one or more actuators attached to the Z stage plate, and a substrate chuck mounted to the stage mirror with constraints on six degrees of freedom of movement of the substrate chuck. The actuators impart movement to the Z stage in a Z direction as the Z stage plate is scanned in a plane perpendicular to the Z direction. The actuators may include force flexures having a base portion attached to the Z stage plate and a cantilever portion extending in a lateral direction from the base portion. The cantilever portion may include a parallelogram flexure coupled between the base portion and a free end of the cantilever portion.