Abstract

Adaptive optics systems, guided by artificial sodium beacons have reached fundamental limits, because of (i) the low densities of atoms in the mesosphere;¹ (ii) the low level of excitation dictated by the requirement to avoid saturation, and (iii) the monochromatic return which makes it impossible to correct for differential tilt (the largest error–about 90%–in image formation).²

© 2001 Optical Society of America