Concept Rendering of the HET: This rendering was produced as part of the initial design effort in 1992. The concept has changed very little. The concept shows the tracker mechanism atop the telescope structure and the primary mirror featuring 91 1-meter hexagonal segments. The dome is 85 feet in diameter and is a 5/8 sphere. The 90-foot-tall Center of Curvature Alignment Sensor (CCAS) tower provides a mounting point at the center of curvature of the primary mirror where a polarization shearing interferometer resides to support positioning of all the mirror segments on the parent sphere. The tower consists of an inner and outer tower to obviate the major effect of wind.