The new Phased Array Mirror, Extendible Large Aperture (PAMELA) technology can be applied to innovative designs for large astronomical telescopes and laser beam directors. Filled primary apertures with diameters exceeding 15 m will be capable of diffraction-limited imaging of objects at visible wavelengths. The same aperture can function as a nearly perfect conventional telescope primary mirror when objects or reference stars are too faint for adaptive compensation of atmospheric turbulence. This performance will be accomplished by means of a dual-mode control system which utilizes either local figure sensing to yield a nearly perfect wide-field, highly segmented mirror or a fully adaptive wavefront compensation system to drive the mirror segments to the phase conjugate positions to correct for atmospheric turbulence within the isoplanatic angle restriction. The active optics sensing for local figure control can be accomplished either by using differential height and tilt sensors on each segment or by using an optical interferometer at the center of curvature of the primary mirror. This paper presents a design concept for a 10-m telescope with a spherical primary mirror composed of about 10,000 10-cm diameter hexagonal segments. Principles of operation are described, and estimates of performance are given.© (1990) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.