An orthonormal hexagonal Zernike basis set is generated from circular Zernike polynomials apodized by a hexagonal mask by use of the Gram-Schmidt orthogonalization technique. Results for the first 15 hexagonal Zernike polynomials are shown. The Gram-Schmidt orthogonalization technique presented can be extended to both apertures of arbitrary shape and other basis functions.

Diffraction-limited performance of 30-m class telescopes requires the integration of structural, optical and control systems to sense and counteract real time disturbances to the telescope. Accurate simulation of an integrated telescope model is essential for optical performance estimation and design validation. Our approach to integrated time domain modeling of large telescopes is to interface commercially available structural, optical and control modeling software packages. The model architecture, data structures, and the interfacing tools of the simulation environment are presented. Preliminary simulation results of a 30-m class telescope subject to wind load and a ground layer phase screen are presented.

The high order adaptive optics (HOAO) system is the centerpiece of the ATST wavefront correction system. The ATST wavefront correction system is required to achieve a Strehl of S = 0.6 or better at visible wavelength. The system design closely follows the successful HOAO implementation at the Dunn Solar Telescope and is based on the correlating Shack-Hartmann wavefront sensor. In addition to HOAO the ATST will utilize wavefront sensors to implement active optics (aO) and Quasi Static Alignment (QSA) of the telescope optics, which includes several off-axis elements. Provisions for implementation of Multi-conjugate adaptive optics have been made with the design of the optical path that feeds the instrumentation at the coudé station. We will give an overview of the design of individual subsystems of the ATST wavefront correction system and describe some of the unique features of the ATST wavefront correction system, such as the need for thermally controlled corrective elements.

Ground-based telescopes operate in a turbulent atmosphere that affects the optical path across the aperture by changing both the mirror positions (wind seeing) and the air refraction index in the light path (atmospheric seeing). In wide field observations, when adaptive optics is not feasible, active optics are the only means of minimizing the effects of wind buffeting. An integrated, dynamic model of wind buffeting, telescope structure, and optical performance was developed to investigate wind energy propagation into primary mirror modes and secondary mirror rigid body motion. Although the results showed that the current level ofwind modeling was not appropriate to decisively settle the need for optical feedback loops in active optics, the simulations strongly indicated the capability of a limited bandwidth edge sensor loop to maintain the continuity of the primary mirror inside the preliminary error budget. It was also found that the largest contributor to the wind seeing is image jitter, i.e. OPD tip/tilt.

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