Abstract: A process for device fabrication is disclosed. In the process, optical lithography is used to introduce an image of a desired pattern into an energy sensitive material. In the process, a filter element is provided. The filter element has at least two regions of different transmittance, each region denominated an aperture. The regions are selected by obtaining information about the desired pattern and an optical lithographic tool that will be used to introduce the image of the desired pattern into the energy sensitive resist material. A filter element that provides an image that, when developed, will provide features with dimensions within acceptable process tolerances is then designed. The filter element is designed by modeling the effects of each aperture of the filter element on the intensity profile of an image of the desired pattern. The combined effect of the apertures is then determined.