Strehl ratio and image sharpness for adaptive optics

Julian C. Christou; Kenneth J. Mighell; Russell B. Makidon

doi:10.1117/12.670430

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28 June 2006 Strehl ratio and image sharpness for adaptive optics

Julian C. Christou, Kenneth J. Mighell, Russell B. Makidon

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Proceedings Volume 6272, Advances in Adaptive Optics II; 62721Y (2006) https://doi.org/10.1117/12.670430
Event: SPIE Astronomical Telescopes + Instrumentation, 2006, Orlando, Florida , United States

Abstract

The performance of an adaptive optics system is typically given in terms of the Strehl ratio of a point spread function (PSF) measured in the focal plane of the system. The Strehl ratio measures the normalized peak intensity of the PSF compared to that of an ideal PSF, i.e. aberration-free, through the system. One advantage of this metric is that it has been shown to be proportional to the rms wavefront error via the Marechel approximation. Thus, Strehl ratio measurements are used to determine the performance of the system. Measurement of the Strehl ratio is frequently problematic in the presence of noise as can be the peak determination for critically sampled data. We have looked at alternative metrics, in particular the S₁ sharpness metric. This metric measures the compactness of the PSF by the normalized sum of the squared image intensity and therefore relates to the intensity variance of the image. Using simulated AO PSFs, we show that there is a unique relationship between S₁ and the Strehl ratio and we can therefore relate it back to the rms wavefront error.

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Julian C. Christou, Kenneth J. Mighell, and Russell B. Makidon "Strehl ratio and image sharpness for adaptive optics", Proc. SPIE 6272, Advances in Adaptive Optics II, 62721Y (28 June 2006); https://doi.org/10.1117/12.670430

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