The mechanical stiffness of sandwich type structures are competitive with other light weight methods. Hextek structured blanks have been analyzed for self weight deflection using detailed FEA (finite element analysis) to predict the optical surface change of a mirror under a variety of orientations at 1g. The results are conclusive, that our substrates can maintain tight optical integrity without much effort. Hextek substrates offer the best stiffness to weight ratio compared to any other light weight mirror design. Some examples of a simple 16″ diameter mirror deflection (with a center hub support only) results appear on this page, courtesy of Hofstadter Analytical Services. The models confirm comparable stiffness to other common light weight configurations by showing a 50nm deflection vs. central hub type of mounting systems. For Hextek substrates, an optimal support system is a whiffle-tree type. When the substrate diameter exceeds 24″ Gas-Fusion structured blanks have superior stiffness and the types of open backed examples illustrated cannot compete. This subject has been treated rigorously and verifies the above conclusions in a book by Ahmad, Anees, ed. “Lightweight Mirror Design.” Handbook of Optomechanical Engineering New York 1997: 125 – 148. Given a mirror design, Hextek Corporation can provide a first order finite element data that predicts mirror deflections and help optimize mirror support locations as part of the design process.