First light for Hokupa'a: 36-element curvature AO system at UH

Abstract
The University of Hawaii adaptive optics program has scaled its previously successful 13 elements AO system to 36 actuators and named it 'Hokupa'a', meaning 'immovable star' in Hawaiian. First light for Hokupa'a in early November of 1997, was on the Canada France Hawaii Telescope on Mauna Kea, an f/35, 3.35 meter telescope. Performance at the telescope has now been measured and compares favorably with that predicted theoretically. The extension to 36 elements has now allowed the system to give diffraction limited performance down to I band on stars as faint as 12.5 magnitude in median 0.7 arcsecond seeing on Mauna Kea. Like our previous system, extensive computer simulations were carried out to achieve the best possible match between the curvature WFS and the deformable curvature mirror.