Diffractional treatment of curvature sensing in segmented mirror telescopes

Jose Maria Rodriguez-Gonzalez; Jesus Jimenez Fuensalida

doi:10.1117/12.457992

4 February 2003 Diffractional treatment of curvature sensing in segmented-mirror telescopes

Jose Maria Rodriguez-Gonzalez, Jesus Jimenez Fuensalida

Proceedings Volume 4837, Large Ground-based Telescopes; (2003) https://doi.org/10.1117/12.457992
Event: Astronomical Telescopes and Instrumentation, 2002, Waikoloa, Hawai'i, United States

Abstract

Discontinuities in the wavefront phase or amplitude affect curvature sensor (CS) response. These discontinuities may be the result of an improper alignment of the elements of a segmented mirror in either piston or tip-tilt. We describe the CS response with an analytical approach based on the Fresnel approximation of the diffracted field and show that a CS is capable of detecting misalignment among segments. The response model that we present leads to a fast algorithm for the measurement of segment positions. As an application, we focus on piston co-phasing. The paper concludes with the characterization of the integrated curvature signal, which simplifies the analysis of the CS response to misalignments. The low processing time and principal memory requirements of the algorithm make it suitable for extremely large telescopes (ELTs).

Citation Download Citation

Jose Maria Rodriguez-Gonzalez and Jesus Jimenez Fuensalida "Diffractional treatment of curvature sensing in segmented-mirror telescopes", Proc. SPIE 4837, Large Ground-based Telescopes, (4 February 2003); https://doi.org/10.1117/12.457992

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