Accuracy of Shack–Hartmann wavefront sensor using a coherent wound fibre image bundle

Jessica R. Zheng*, Michael Goodwin, Jon Lawrence

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

Shack–Hartmannwavefront sensors using wound fibre image bundles are desired for multi-object adaptive optical systems to provide large multiplex positioned by Starbugs. The use of a large-sized wound fibre image bundle provides the flexibility to use more sub-apertures wavefront sensor for ELTs. These compact wavefront sensors take advantage of large focal surfaces such as the Giant Magellan Telescope. The focus of this paper is to study the wound fibre image bundle structure defects effect on the centroid measurement accuracy of a Shack–Hartmann wavefront sensor. We use the first moment centroid method to estimate the centroid of a focused Gaussian beam sampled by a simulated bundle. Spot estimation accuracy with wound fibre image bundle and its structure impact on wavefront measurement accuracy statistics are addressed. Our results show that when the measurement signal-to-noise ratio is high, the centroid measurement accuracy is dominated by the wound fibre image bundle structure, e.g. tile angle and gap spacing. For the measurement with low signal-to-noise ratio, its accuracy is influenced by the read noise of the detector instead of the wound fibre image bundle structure defects. We demonstrate this both with simulation and experimentally. We provide a statistical model of the centroid and wavefront error of a wound fibre image bundle found through experiment.

Original languageEnglish
Article numbere014
Number of pages16
JournalPublications of the Astronomical Society of Australia
Volume35
Early online date26 Mar 2018
DOIs
Publication statusPublished - 2018
Externally publishedYes

Keywords

  • instrumentation: adaptive optics

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