STATUS OF THE GIRMOS MOAO DEMONSTRATOR

We present the last developments of the Multi-Object Adaptive Optics (MOAO) demonstrator for the Gemini Infra-Red Multi-Object Spectrograph (GIRMOS). The GIRMOS MOAO system will able to deliver an image quality close to the diffraction-limit in the near-infrared (1.0-2.4 mu m) by taking advantage of the GLAO corrected wavefront delivered by the future Gemini North Adaptive Optics (GNAO) facility and performing an additional MOAO correction. MOAO is particularly challenging and risky because the DM is controlled in open-loop and usually subject to the so-called DM go-to-error which are difficult to model and manage. Therefore, as part of the preliminary design phase of the instrument, we decided to build a one-to-one scale demonstrator to mitigate some risks, exercise MOAO calibration techniques between two AO systems (GNAO and GIRMOS) and characterize of the MOAO performance. GIRMOS is a complex AO instrument and to circumvent the cost and complexity of such a system we are using a spatial light modulator (SLM) allowing the generation of turbulence in specific directions in the field without the need of pick-off system. In this paper, we present the status of the GIRMOS MOAO prototype. We exercised MOAO calibration and characterized the open-loop error and the GIRMOS MOAO performance in laboratory. We found, thanks to the GLAO- MOAO design, a very small open-loop error of about 60 nm rms. In addition, the GIRMOS MOAO design includes a figure source to compensate the DM accuracy errors. Using the figure source in laboratory, we compensated about 37 nm rms of go-to errors reducing the open-loop error down to 44 nm rms.