Adaptive optics advancement at the Giant Magellan Telescope

Abstract

The adaptive optics system is the keystone for attaining high image quality in an extremely large segmented-aperture telescope like the Giant Magellan Telescope. We report on the progress in the development of wavefront sensors and control algorithms for the two diffraction-limited AO observation modes on the Giant Magellan Telescope. The GMT wavefront sensing and control suite of subsystems comprises three wavefront sensors, an Adaptive Optics Test Camera for verification of AO control algorithm and a laser guide star facility for carrying out laser tomographic atmospheric correction. We have advanced the designs of all of these subsystems. We have invested strategically in testbeds and prototypes to de-risk the designs and the control strategies. We have recently built the GAPS (GMT Adaptive Optics and Phasing Sensor) testbed to test and verify performance of the NGAO (Natural Guide Star AO) mode using the existing Natural Guide Star Wavefront Sensor prototype. GAPS will demonstrate simultaneous correction of both segment piston error and high order atmospheric turbulence in a relevant GMT-like environment. We have also advanced the LTAO (Laser Tomography AO) mode by testing mechanical and camera prototypes of the Laser Tomography Wavefront Sensor used to measure the six-guide star asterism for tomographic reconstruction. We have developed an Adaptive Optics Test Camera (AOTC) to verify performance of the Adaptive Secondary Mirror and the wavefront sensing and control algorithms for both NGAO and LTAO modes. We report on the preliminary design of the AOTC.