Contorted mirror reduction of projected image distortion

An analysis is made of the degree to which a simple contorted mirror can reduce distortion in a projected image. Although it is impossible in general to remove the distortion completely by this means, significant reduction may be achieved. Equations are derived for the shape of a mirror which will give the maximum reduction possible. Equations are also developed for how to stress a planar mirror to create the desired optimal shape. Image blurring is estimated. An example is presented in which this technique is used to reduce the distortion which results when a projection lens appropriate for projection onto a flat screen is used instead to project onto a spherical surface from an oblique angle.