Determination of Aspheric Reference Sphere by Tri-point Method

Based on the condition of aspheric production, the method how to get the aspheric reference sphere is presented in this paper. The calculating method of the reference sphere is analyzed in detail, by calculating the reference sphere of a paraboloid and comparing it with the result of the least square method.The tri-point method has a merit of simple calculation and it is adapted to the process of the craft.