AO4ELT5 Proceedings

Feedback control baseline for GTC adaptive optics with NGS

Nuñez , Miguel (Instituto de Astrofísica de Canarias)

Gran Telescopio Canarias Adaptive Optics (GTCAO) with NGS is a single-conjugated post-focal system with a Shack Hartmann wavefront sensor at visible wavelength, one Deformable Mirror (DM) and the telescope secondary mirror that is used to correct partially the tip-tilt. GTCAO feeds the scientific instrument FRIDA, which is an imager and integral field spectrograph with an image slicer. Bandwidth error has been calculated creating models for tip-tilt and high order optical modes. The error functions has been applied to representative atmospheric conditions that has been chosen based on sky characterization data from “Observatorio del Roque los Muchachos” such as coherence time or the guide star flux. Three different strategies are analysed for tip-tilt correction and one of them is proposed to be implemented. The main difference between the implementation in laboratory and the commissioning in telescope is the absence of the secondary mirror in the laboratory, an important element in the control loop that will off-load the DM, correcting tip-tilt perturbations at low temporal frequencies.

DOI: 10.26698/AO4ELT5.0182- Proceeding PDF

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