7 March 2014 Improving Shack-Hartmann wavefront sensor by using sub-wavelength annular apertures
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Proceedings Volume 8982, Optical Components and Materials XI; 89821Z (2014) https://doi.org/10.1117/12.2039149
Event: SPIE OPTO, 2014, San Francisco, California, United States
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.
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Hao-Jung Chang, Hao-Jung Chang, Ming-Han Chung, Ming-Han Chung, Chih-Kung Lee, Chih-Kung Lee, } "Improving Shack-Hartmann wavefront sensor by using sub-wavelength annular apertures", Proc. SPIE 8982, Optical Components and Materials XI, 89821Z (7 March 2014); doi: 10.1117/12.2039149; https://doi.org/10.1117/12.2039149
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