An imaging microoptics, which is compact and robust, includes at least one aspherical member and has a folded beam path. The imaging microoptics provides a magnification |β′| of >800 by magnitude. Furthermore, a system for positioning a wafer with respect to a projection optics includes the imaging microoptics, an image sensor positionable in the image plane of the imaging microoptics, for measuring a position of an aerial image of the projection optics, and a wafer stage with an actuator and a controller for positioning the wafer in dependence of an output signal of the image sensor.