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Optical Engineering

Optical phase modulation using a refractive lenslet array and micro-electro-mechanical deformable mirror
Author(s): William D. Cowan; Max K. Lee; Byron M. Welsh; Victor M. Bright; Michael C. Roggemann
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Paper Abstract

Microelectromechanical deformable mirrors (MEM-DMs) are attractive for optical phase modulation applications primarily because of their inherently low cost and low drive voltages. Two problems limiting widespread use of segmented piston MEM-DMs are low optical efficiency (fill factor) and undesired amplitude modulation resulting from interference with the static background structure. Using a lenslet array to focus the incident light onto only the reflective surface of the MEM-DM greatly improves the effective fill factor with a corresponding decrease in interference effects. A refractive lenslet array is used with a very low fill factor MEM-DM ( ~ 7%) to comprise a correcting element that behaves like a 70 to 80% fill factor device. The MEM-DM has 128 active piston micromirror elements. Experiments employing the hybrid correcting element demonstrate single beam steering, dual beam steering, and optical aberration correction. A comprehensive model of the lenslet/MEM-DM geometry is developed. Measured data shows good agreement with model predictions. A thermal circuit model is developed to estimate optical power handling capability of the MEM-DM. A conservative estimate of maximum optical power for this particular MEM-DM is 4 W/element when operated in a helium ambient, suggesting that relatively high power laser control applications are feasible.

Paper Details

Date Published: 1 December 1998
PDF: 11 pages
Opt. Eng. 37(12) doi: 10.1117/1.601998
Published in: Optical Engineering Volume 37, Issue 12
Show Author Affiliations
William D. Cowan, Air Force Research Lab (United States)
Max K. Lee, Univ of Dayton (United States)
Byron M. Welsh, Mission Research Corp. (United States)
Victor M. Bright, Univ. of Colorado/Boulder (United States)
Michael C. Roggemann, Michigan Technological Univ. (United States)

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