Conic that best fits an off-axis conic section

Abstract

To help in the fabrication of off-axis conic sections, we present a method of approximating this off-axis section by an on-axis conic centered on the portion desired. This method is based on the continuum least-squares method to obtain the vertex’s curvature and conic constant of the fitted conic on-axis, given the curvature at the vertex and the conic constant of the parent conic from where we want the section and the size of that section. Simple analytic expressions for the curvature and conic constant are derived in terms of the parameters of the off-axis section.