An integration of microoptical components to three-dimensional systems is of interest for optical information processing as well as for optical interconnections. Polymethyl methacrylate (PMMA) is a suitable substrate material, because microprisms, beamsplitters and microlenses can be integrated monolithically in the same substrate by deep proton irradiation. The microcomponents can be combined to compact microoptical imaging systems which are easy to align. The fabrication method and the imaging properties of this system are discussed.