Analysis of double conjugate zoom lens using tunable-focus lenses

The work is focused on an analysis and modeling of paraxial imaging parameters of an optical system with a variable magnification or focal length, which keeps the position of object and image planes and entrance and exit pupil planes fixed. This system does not move its elements during the change of the magnification or the focal length. Such an effect can be achieved using tunable-focus active lenses. The described double conjugate zoom lens with tunable-focus lenses satisfies the requirement that object, image and pupil planes are fixed during the change of magnification or focal length. The system must be composed of at minimum three optical elements. Formulas are derived, which enable to determine focal lengths of individual elements of the optical system in a general case, when an object is situated in a finite or infinite distance from the optical system. Such an optical system can be principally used in the design of riflescopes with a variable magnification. This design of the riflescope has the advantage of the fixed position of its optical components (tunable-focus lenses). Further, the position of the exit pupil does not change and stays fixed in a fixed distance from the eyepiece during the change of magnification.