Paraxial design of four-component zoom lens with fixed position of optical center composed of members with variable focal length.

The paper presents paraxial analysis of special types of zoom lenses, which are composed of four members with variable focal length. The position of optical center of these systems is required to be fixed for a given value of focal length (i.e., the position of the optical center does not depend on object distance for given value of focal length of the zoom). The formulas that enable the calculation of the optical powers of individual members of such a zoom lens are derived from--and the practical application of the derived formulas is demonstrated with--an example. Such optical systems represent a completely new family of zoom optical systems with applications in measuring systems in photogrammetry, computer vision, triangulation sensors, fringe projection techniques, surveying, machine vision, and so forth.