Method of first-order analysis of a three-element two-conjugate zoom lens.

A method is described for the first-order analysis of a two-conjugate zoom lens composed of three movable elements. Such an optical system satisfies the requirement that the object, image, and pupil planes are fixed within the change of its magnification. General formulas are derived for the calculation of parameters of a three-component two-conjugate zoom lens system, which enable us to calculate the optical power of individual optical elements and their distances for a different range of magnification and imposed conditions. The application of derived formulas is presented on three examples of optical systems with different parameters.