Optimized micromirror arrays for adaptive optics
- University of Colorado at Boulder, Department of Mechanical Engineering, Boulder, Colorado 80309-0427 (United States) Comtois, John H. [Air Force Research Laboratory (VSSE), 3550 Aberdeen Avenue SE, Kirtland AFB, New Mexico 87117-5776 (United States) Hetherington, Dale L. [Sandia National Laboratories, Org. 01325, Mail Stop 1080, Kirtland AFB, New Mexico 87185-1080 (United States)
This paper describes the design, layout, fabrication, and surface characterization of highly optimized surface micromachined micromirror devices. Design considerations and fabrication capabilities are presented. These devices are fabricated in the state-of-the-art, four-level, planarized, ultra-low-stress polysilicon process available at Sandia National Laboratories known as the Sandia Ultra-planar Multi-level MEMS Technology (SUMMiT). This enabling process permits the development of micromirror devices with near-ideal characteristics that have previously been unrealizable in standard three-layer polysilicon processes. The reduced 1 {mu}m minimum feature sizes and 0.1 {mu}m mask resolution make it possible to produce dense wiring patterns and irregularly shaped flexures. Likewise, mirror surfaces can be uniquely distributed and segmented in advanced patterns and often irregular shapes in order to minimize wavefront error across the pupil. The ultra-low-stress polysilicon and planarized upper layer allow designers to make larger and more complex micromirrors of varying shape and surface area within an array while maintaining uniform performance of optical surfaces. Powerful layout functions of the AutoCAD editor simplify the design of advanced micromirror arrays and make it possible to optimize devices according to the capabilities of the fabrication process. Micromirrors fabricated in this process have demonstrated a surface variance across the array from only 2{endash}3 nm to a worst case of roughly 25 nm while boasting active surface areas of 98{percent} or better. Combining the process planarization with a {open_quotes}planarized-by-design{close_quotes} approach will produce micromirror array surfaces that are limited in flatness only by the surface deposition roughness of the structural material. Ultimately, the combination of advanced process and layout capabilities have permitted the fabrication of highly optimized micromirror arrays for adaptive optics. {copyright} {ital 1999 American Institute of Physics.}
- Research Organization:
- Sandia National Laboratories (SNL), Albuquerque, NM, and Livermore, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 700891
- Report Number(s):
- CONF-990103-; ISSN 0094-243X; TRN: 9911M0019
- Journal Information:
- AIP Conference Proceedings, Vol. 458, Issue 1; Conference: 1999 space technology and applications international forum, Albuquerque, NM (United States), 31 Jan - 4 Feb 1999; Other Information: PBD: Jan 1999
- Country of Publication:
- United States
- Language:
- English
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