Integrating AO in a performance budget: towards a global system engineering vision


Philippe Laporte (a) and Hermine Schnetler (b)


(a) GEPI, (b) UK ATC


EAGLE (Extremely large Adaptive telescope for GaLaxy Evolution) is one of the eight E-ELT instruments concepts that was developed as part of the Phase A E-ELT instrument studies. EAGLE is a near-infrared wide field multi object spectrograph. It includes its own multi-object adaptive optics system (MOAO) and its subsystems are cooled down so as to ensure that the instrument can both achieve the desired spatial resolution in the K-band and to ensure that the instrument is background limited, as required in the primary science case. In this paper we describe the method we put in place to partition and allocate the important characteristics to the various subsystems and how the adaptive optics improves the overall performance. We also discuss the process which verify that the concept design will deliver the required characteristics. Due to the integrated nature of the instrument, a large number of AO parameters have to be controlled. The performance matrix also has to deal with the added complexity of active optical elements such as the science channel deformable mirrors (DMs). This paper also defines a method of how to convert the ensquared energy (EE) and signal-to-noise ratio (SNR) required by the primary science case into the “as designed” wavefront error and the overall residue wavefront error. To ensure successful integration and verification of the next generation instruments for ELT it is of the utmost importance to have method to control and managed the instrument’s critical performance characteristics using adaptive optics.

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