The first successful demonstration of actively phase matching, coaligning, and agilely steering a number of mutually coherent optical wavefronts through an array of transmitting telescopes has been performed on the Phasar experiment at the Air Force Weapons Laboratory. In the Phasar experiment, modern wavefront sensing and feedback techniques are used to control wavefronts transmitted through an assembly of three independent optical telescopes. Mutually coherent wavefronts transmitted through the telescope array are controlled to produce an effective single aperture wavefront. The multiple phased wavefronts produce a far-field energy distribution equivalent to the diffraction pattern of a single aperture whose diameter and obscurations match the geometry of the transmitting array. The Phasar experiment demonstrates absolute phasing of a broadband source in the presence of dynamic disturbances. The technologies developed facilitate the construction of large aperture, high quality optical systems by the modular combination of relatively small, inexpensive telescopes.