Initial opto-thermal modelling of the EAGLE instrument to maximise SNR performance and resulting design considerations

Philippe Laporte; Fanny Chemla; Mathieu Puech; Eric Gendron; Peter Hastings; Pascal Vola

doi:10.1117/12.787832

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9 July 2008 Initial opto-thermal modelling of the EAGLE instrument to maximise SNR performance and resulting design considerations

Philippe Laporte, Fanny Chemla, Mathieu Puech, Eric Gendron, Peter Hastings, Pascal Vola

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Proceedings Volume 7014, Ground-based and Airborne Instrumentation for Astronomy II; 701463 (2008) https://doi.org/10.1117/12.787832
Event: SPIE Astronomical Telescopes + Instrumentation, 2008, Marseille, France

Abstract

E-ELT will provide a unique opportunity to observe the early universe since its large collecting area will allow detecting faint objects at high redshifts. Primordial galaxies are a key topic for cosmology and for understanding the behaviour of the galaxies in the universe. To achieve these observations, future instruments for the E-ELT will have to provide high sensitivity over a wide range of wavelengths from 1 μm up to 2.5 μm - the upper limit being imposed by the redshift which shifts the OII and Hα lines. For the EAGLE instrument mainly devoted to such observations, we have studied the opto-thermal behaviour of the complete system (TAS - Target Acquisition System - and the spectrograph) to estimate the thermal emission of the optical and the mechanical parts which become a major contributor to the background above 2.2 μm. The nominal operating temperature is a key parameter we must define precisely to both reduce the thermal background and optimise the cooling system in terms of cost and complexity. The results of the simulations show that the TAS and the spectrograph contribute to the thermal background at a similar level and what the optimal temperature should be. We then discuss how such an 'optimal design' might be implemented in practice.

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Philippe Laporte, Fanny Chemla, Mathieu Puech, Eric Gendron, Peter Hastings, and Pascal Vola "Initial opto-thermal modelling of the EAGLE instrument to maximise SNR performance and resulting design considerations", Proc. SPIE 7014, Ground-based and Airborne Instrumentation for Astronomy II, 701463 (9 July 2008); https://doi.org/10.1117/12.787832

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