AO4ELT5 Proceedings

Laser Guide Star Objective of MAORY

Lombini, Matteo (INAF - OABO)

The Multi Conjugate Adaptive Optics Relay (MAORY) for the European Extremely Large Telescope is planned to be located on the straight-through port of the telescope Nasmyth platform and shall re-image the telescope focal plane to a wide field camera (MICADO) and a possible future second instrument. By means of natural and artificial (laser) reference sources for wavefront sensing, and of deformable mirrors for wavefront correction, MAORY shall be able to compensate the wavefront disturbances affecting the scientific observations, achieving high Strehl ratio and very low geometric distortion. Inside the Post Focal Relay, the light at 589nm of the 6 sodium laser sources will be split from the longer wavelength light by a dichroic placed close to a pupil image and focused, by means an objective, into an image plane where the wavefront sensors will be placed. The image plane of the laser stars will shift along the optical path due to the variation of the Sodium layer distance with the Zenith angle. The objective shall maintain fixed the exit pupil position and the focal aperture for the different altitudes. Moreover the non-common path wavefront error and the pupil image optical quality should not affect significantly the wavefront reconstruction. We present in this paper the optical design and the tolerance analysis of the objective.

DOI: 10.26698/AO4ELT5.0056- Proceeding PDF

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