Focal ratio degradation: a new perspective

Dionne M. Haynes; Michael J. Withford; Judith M. Dawes; Roger Haynes; Joss Bland-Hawthorn

doi:10.1117/12.788735

23 July 2008 Focal ratio degradation: a new perspective

Dionne M. Haynes, Michael J. Withford, Judith M. Dawes, Roger Haynes, Joss Bland-Hawthorn

Proceedings Volume 7018, Advanced Optical and Mechanical Technologies in Telescopes and Instrumentation; 70182U (2008) https://doi.org/10.1117/12.788735
Event: SPIE Astronomical Telescopes + Instrumentation, 2008, Marseille, France

Abstract

We have developed an alternative FRD empirical model for the parallel laser beam technique which can accommodate contributions from both scattering and modal diffusion. It is consistent with scattering inducing a Lorentzian contribution and modal diffusion inducing a Gaussian contribution. The convolution of these two functions produces a Voigt function which is shown to better simulate the observed behavior of the FRD distribution and provides a greatly improved fit over the standard Gaussian fitting approach. The Voigt model can also be used to quantify the amount of energy displaced by FRD, therefore allowing astronomical instrument scientists to identify, quantify and potentially minimize the various sources of FRD, and optimise the fiber and instrument performance.

Citation Download Citation

Dionne M. Haynes, Michael J. Withford, Judith M. Dawes, Roger Haynes, and Joss Bland-Hawthorn "Focal ratio degradation: a new perspective", Proc. SPIE 7018, Advanced Optical and Mechanical Technologies in Telescopes and Instrumentation, 70182U (23 July 2008); https://doi.org/10.1117/12.788735

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