21 July 2014 Meaningful options for a dichroic unit within the natural & laser guide star AO systems at the Giant Magellan Telescope
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The use of tilted elements in fast convergent beams like a dichroic unit is always a delicate matter in optical design. In adaptive optics (AO) applications this issue proves itself to be more severe with respect to classical imaging or spectroscopy: this due to the fact that the laser is co-moving with the launch telescope system while the natural guide star is co-moving with the sky. Because of the GMT design, during AO operations this condition translates as that the laser guide star moves around the target while the natural guide star does not. In this context, we studied two options for a high-optical quality and an easy to-plug-in dichroic unit dividing lasers beacons (reflected) and natural stars (transmitted). Beyond their different optical performances and mechanical implementations, these options are able both to accomplish the main goal of simultaneous operation of natural and laser-oriented AO at the GMT. One of these two has successfully passed the GMT AO Preliminary Design Review (PDR) on July 2013.
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Jacopo Antichi, Enrico Pinna, Simone Esposito, Marco Bonaglia, Lorenzo Busoni, Fernando Santoro, Antonin Bouchez, "Meaningful options for a dichroic unit within the natural & laser guide star AO systems at the Giant Magellan Telescope", Proc. SPIE 9148, Adaptive Optics Systems IV, 91484X (21 July 2014); doi: 10.1117/12.2054601; https://doi.org/10.1117/12.2054601


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