Developing the prototype adaptive optics system for the Gemini infra-red multi-object spectrograph

We present our development of the Multi-Object Adaptive Optics (MOAO) system for the Gemini Infra-Red Multi-Object Spectrograph (GIRMOS). The GIRMOS MOAO system consists of four identical arms patrolling over a large field-ofregard (2 arcmin) and able to deliver an image quality close to the diffraction-limit in the near-infrared. The AO system of GIRMOS will performed MOAO correction on top of the wavefront delivered by the Gemini North AO (GNAO) system. We are currently prototyping one arm in the laboratory in order to validate the simulated performances and characterize the hardware as well as different MOAO control strategies. GIRMOS MOAO is a complex AO system and a complete lab characterization would require a full GNAO simulator with a pick-off system and multiple wavefront sensors (WFS), light sources, etc. To circumvent the cost and complexity of such a system we are using a spatial light modulator (SLM) allowing the generation of residual turbulences in specific directions in the field without the need of pick-off system. Coupled with a numerical end-to-end model of the system, our bench is focused on open-loop control rather than tomography. In this paper, we review the GIRMOS MOAO preliminary design of the system, the baseline performances and the status of the testbed.