Investigation of a telescopic systems with three-stage magnification change and a stable exit pupil position

The visual optical systems with three fields of view are considered in the article. The removal of the exit pupil of the considered systems is from 1/3 to 1/4 of its total length. The problems that arise during a three-stage change of magnification are considered in the paper. An important feature of such systems is the need to match the pupils of the system when changing the magnification to ensure the stability of the position of the exit pupil. The complexity of the implementation while observing weight and size restrictions are also discussed. A comprehensive solution to these problems should be laid at the circuit level and should be based on the search for a fundamental structural optical scheme. During the design process, the issues of modeling and determining the area of solutions are revealed, which make it possible to ensure high image quality in the transition to finite apertures and thicknesses. The scientific hypothesis is that a three-stage change of magnification can be realized by presence of the rotary afocal system of magnification change. At the same time, for such a solution, internal alignment and competitive characteristics of the optical system of the product as a whole are also provided. The purpose of this article is to present the results of the analysis of the circuit solution in the paraxial approximation, to determine the areas of solutions that provide the smallest relative apertures of the circuit components under the introduced overall restrictions on the length of the system, the diameters of the components and the removal of the exit pupil. The results of the study are confirmed by the development of an optical system with interchangeable magnifications of 1x, 3x and 9x with an eye relief of 80 mm with the total system length of 250 mm.