6 October 2017 Black silicon integrated aperture
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This paper describes the incorporation of nanotextured black silicon as an optical absorbing material into silicon-based micro-optoelectromechanical systems devices to reduce stray light and increase optical contrast during imaging. Black silicon is created through a maskless dry etch process and characterized for two different etch conditions, a cold etch performed at 0°C and a cryogenic etch performed at 110 ° C . We measure specular reflection at visible wavelengths to be < 0.001 % at near-normal incidence for both processes, whereas the total diffuse scatter is < 3 % and 1% for the cold and cryogenic processes, respectively. These surfaces exhibit less reflectivity and lower scatter than black velvet paint used to coat optical baffles and compare favorably with other methods to produce black surfaces from nanotextured silicon or using carbon nanotubes. We illustrate the use of this material by integrating a black silicon aperture around the perimeter of a deformable focus-control mirror. Imaging results show a significant improvement in contrast and image fidelity due to the effective reduction in stray light achieved with the self-aligned black aperture.
© 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)
Tianbo Liu, Tianbo Liu, David L. Dickensheets, David L. Dickensheets, } "Black silicon integrated aperture," Journal of Micro/Nanolithography, MEMS, and MOEMS 16(4), 045501 (6 October 2017). https://doi.org/10.1117/1.JMM.16.4.045501 . Submission: Received: 21 July 2017; Accepted: 7 September 2017
Received: 21 July 2017; Accepted: 7 September 2017; Published: 6 October 2017

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