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A theoretical model based on thin plate theory is developed to calculate mirror deflection on multiple axial supports. Thickness variation due to mirror curvature, sandwich structure, and shear effects is included in this model. Comparison with the finite element analysis shows almost identical results for a three-point support. Surface deflections due to more complicated support patterns (forty-eight- and eighty-four-point support) are also included. A tolerancing model of support forces is developed and applied to the case of eight-four-point support.

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An aspherical mirror is made by a thin-film coating technique. A special mask is placed between the evaporation source and the substrate that is to be coated as an aspheric. The design principle of the mask is fully described. An ion-assisted deposition technique is used to relieve aluminum film stress and to increase surface reflectance. The final wave front is tested by conventional interferometric methods for aspherics. Less than one-fifth of a wave (632.8 nm) of spherical aberration is achieved without much trial and error.