Future large ground-based telescopes

Optical telescopes in the 40 m class with adaptive optics have a large astronomical potential. Adaptive optics may be implemented using the telescope mirrors as deformable elements. Several possibilities exist for the primary minor. It may be segmented or monolithic. A segmented primary could have 2 m segments and be spherical or parabolic. A monolithic 40 m primary mirror blank could be manufactured of Borosilicate on-site using spin casting techniques. Also, it could be made of Carbon Fiber Reinforced Plastic or aluminum on-site. Choice of primary mirror configuration and optical layout are closely interrelated. Several optical designs are presented and two candidates are selected for the spherical and parabolic primary mirror cases, respectively. Further studies of the monolithic primary solution are in progress.