106 research outputs found
Centroid Detection by Gaussian Pattern Matching in Adaptive Optics
Shack Hartmann wavefront sensor is a two dimensional array of lenslets which
is used to detect the incoming phase distorted wavefront through local tilt
measurements made by recording the spot pattern near the focal plane. Wavefront
reconstruction is performed in two stages - (a) image centroiding to calculate
local slopes, (b) formation of the wavefront shape from local slope
measurement. Centroiding accuracy contributes to most of the wavefront
reconstruction error in Shack Hartmann sensor based adaptive optics system with
readout and background noise. It becomes even more difficult in atmospheric
adaptive optics case, where scintillation effects may also occur. In this paper
we used a denoising technique based on thresholded Zernike reconstructor to
minimize the effects due to readout and background noise. At low signal to
noise ratio, this denoising technique can be improved further by taking the
advantage of the shape of the spot. Assuming a Gaussian pattern for individual
spots, it is shown that the centroiding accuracy can be improved in the
presence of strong scintillations and background.Comment: 6 pages, 14 figures, Accepted for publication in the International
Journal of Futuristic Computer Application
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