We report on the fabrication of aspherical refractive microlens arrays on 8'' fused silica and silicon wafers at Suss Neuchatel, Switzerland. Refractive, plano-convex microlenses are fabricated by using photolithography, a reflow or melting resist technique and reactive ion etching. Diffraction-limited optical performance of the microlenses is achieved for refractive microlenses from 100 microns to 1.5 mm diameter and 2 to 50 microns sag. Aspherical lens profiles (aspherical constant from k equals -0.5 to -5.2) are obtained by varying the etch parameters during the reactive ion etching transfer. Microlens arrays in fused silica and silicon are fabricated for high-efficient fiber coupling and telecommunication. Densely packed arrays of cylindrical lenses (packing density > 98%, parabolic profile) are fabricated for flattop illumination at UV-wavelengths. Excellent array uniformity of is required for microlenses used within Microlens Projection Lithography systems.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.