The "conventional" procedure in evaluating the image degradation caused by deformed optical surfaces uses only the local Z-component of the optical surface's nodal displacement vector along with the nominal X and Y-coordinates directly from a finite-element model (FEM) to evaluate a Zernike polynomial. The surface's decenter is handled separately. This method may produce significant errors if thermal loads and complex load combinations are considered. An alternative vector approach, which overcomes this problem in a single step, is presented.
The Phased Array Mirror, Extendible Large Aperture telescope has been fully assembled and testing has started. The telescope is the first to have a fully adaptive primary mirror, which consists of 36 hexagonal injection-molded Pyrex segments that are seven centimeters flat-to- flat. The segments are mounted on three long-throw voice-coil actuators for tip, tilt, and piston motion. The segment tiles are measured with a Hartmann-Shack wavefront sensor and the piston errors between adjacent segments are measured via inductive edge-sensors. The personnel at NASA MSFC are performing a significant amount of testing in the area of controls/structure interactions; therefore, in addition to a description of the optical performance and aberration correction capability of the telescope, a description of the plan to model the mechanical structure with emphasis on how this will interact with the adaptive optics system is presented.