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Proceedings Paper

Improving Shack-Hartmann wavefront sensor by using sub-wavelength annular apertures
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Paper Abstract

Out of the many wavefront sensing techniques, Shack Hartmann wavefront sensor remains the most popular and the most versatile. Its optical configuration utilized a micro-lens array to measure the directivity of the light beam associated with each micro-lens. In this design, smaller size of micro-lens leads to angular resolution improvement. However, smaller size micro-lens typically is associated to shorter depth of focus, which makes it difficult to focus on sensor array properly. In addition, the size of micro-lens array is limited by the diffraction limit. In today’s technology, micro-lens with dimensions in size of a few hundred of microns is possible. This dimension posts the limitation of the angular resolution possible for Shack Hartmann wavefront sensor. To alleviate the compromise between the angular resolution and the depth of focus, a sub-wavelength annular aperture (SAA) structure was developed to generate Bessel light beams. That is, the SAA performs similar functions as that of the micro lens array in traditional wave front sensors. It is shown that this design maintains a sub-wavelength focusing capability while achieves tens of micron depth of focus in the far-field region, which leads to an improved wavefront sensor. Both simulation and experimental results are detailed.

Paper Details

Date Published: 7 March 2014
PDF: 9 pages
Proc. SPIE 8982, Optical Components and Materials XI, 89821Z (7 March 2014); doi: 10.1117/12.2039149
Show Author Affiliations
Hao-Jung Chang, National Taiwan Univ. (Taiwan)
Ming-Han Chung, National Taiwan Univ. (Taiwan)
Chih-Kung Lee, National Taiwan Univ. (Taiwan)

Published in SPIE Proceedings Vol. 8982:
Optical Components and Materials XI
Michel J. F. Digonnet; Shibin Jiang, Editor(s)

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