The present article discusses steps for the realistic description of optical properties of micro-mirror arrays (MMA), which are utilized as programmable masks for microlithography. The article focuses on global contrast as an elementary example for the understanding of MMA's diffractive operation principle. Central point will be a discussion of those MEMS properties that influence the global MMA contrast, and how to introduce them into simulation. Surface corrugations of single mirrors and slit properties will be taken into account. Comparison is made with experimental contrast data to validate the theoretical assumptions.
