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http://dx.doi.org/10.3807/HKH.2007.18.6.375

A Study on the Dynamic Range Expansion of the Shack-Hartmann Wavefront Sensor using Image Processing  

Kim, Min-Seok (Doosan Heavy Industries and Construction Co. Ltd)
Kim, Ji-Yeon (Department of Mechanical Engineering, KAIST)
Uhm, Tae-Kyung (Department of Mechanical Engineering, KAIST)
Youn, Sung-Kie (Department of Mechanical Engineering, KAIST)
Lee, Jun-Ho (Department of Optical Engineering, Kong-Ju National University)
Publication Information
Korean Journal of Optics and Photonics / v.18, no.6, 2007 , pp. 375-382 More about this Journal
Abstract
The Shack-Hartmann wavefront sensor is composed of a lenslet array generating the spot images from which local slope is calculated and overall wavefront is measured. Generally the principle of wavefront reconstruction is that the spot centroid of each lenslet array is calculated from pixel intensity values in its subaperture, and then overall wavefront is reconstructed by the local slope of the wavefront obtained by deviations from reference positions. Hence the spot image of each lenslet array has to remain in its subaperture for exact measurement of the wavefront. However the spot of each lenslet array deviates from its subaperture area when a wavefront with large local slopes enters the Shack-Hartmann sensor. In this research, we propose a spot image searching method that finds the area of each measured spot image flexibly and determines the centroid of each spot in its area Also the algorithms that match these centroids to their reference points unequivocally, even if some of them are situated off the allocated subaperture, are proposed. Finally we verify the proposed algorithm with the test of a defocus measurement through experimental setup for the Shack-Hartmann wavefront sensor. It has been shown that the proposed algorithm can expand the dynamic range without additional devices.
Keywords
Shack-Hartmann Sensor; Dynamic Range; Image Processing;
Citations & Related Records
Times Cited By KSCI : 1  (Citation Analysis)
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