Abstract: THis paper presents optical testing of polysilicon surface micromachined piston micromirror arrays. Similar piston micromirror arrays were fabricated using two different commercially available surface micromachining foundry processes: the DARPA supported multi-user MEMS processes (MUMPs), and Sandia Ultra-planar Multi-level MEMS Technology (SUMMiT). All test arrays employ square reflecting elements in an 8 $MUL 8 element 203 $mu@m square grid. Fabrication constraints limit the MUMPs designs to fill-factors of less than 80 percent. The chemical mechanical polishing planarization step integral to the SUMMiT process allows an as-drawn fill-factor of 95 percent to be easily achieved. MUMPs designs employ both the standard gold metallization and maskless sputtered chromium/gold post-process metallization, while post process metallization is the only option for the SUMMiT design. Testing of the micromirror arrays focuses on microscope interferometer characterization of mirror topography, and measurement of the far field diffraction pattern for each. The measured results show that control of the individual micromirror element surface topography is more important for imaging applications than maximizing the as-drawn fill-factor. !10
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