Automated design of zoom riflescope with extended parameters

Sokurenko V. M., Sokurenko O. M. 
AUTOMАТED DESIGN OF ZOOM RIFLESCOPE WITH EXTENDED PARAMETERS 
Background. Designing an arbitrary afocal zoom optical system is a complex and multidimensional problem. It cannot be solved analytically and requires the essential experience and efforts of the designer. 
Objective. The purpose of the paper is to present and verify by simulation the method and means to perform an automated design of complex multi-lens afocal zoom optical systems having variable parameters and characteristics. 
Methods. Using the developed specialized software with implemented modification of the adaptive Cauchy differential evolution algorithm for the parametric synthesis of multi-component optical systems of zoom riflescopes with extended functional parameters. 
Results. The developed optical system of the riflescope provides the 5× magnification ratio and the angular field of view in the object space from 3.26° to 0.83°. It has a reticle located in the first focal plane, the entrance pupil diameter of 60 mm, the eye relief within the range 106...111 mm, and the maximum system length of 390 mm. The riflescope contains 13 lenses in 10 components. The performed simulations showed that the time interval required for direct automated design of the riflescope’s optical system is about 30 hours for the total number of unknown parameters (variables) equal to 91. The root-mean-square values ​​of the angular aberrations of axial beams in all (five) configurations of the synthesized zoom system do not exceed 1.25 arc minute in the whole spectral range. The algorithm helps to determine the prescription data of optical systems, taking into account the technical requirements and restrictions specified by the designer. 
Conclusions: Computer simulations of the development of the zoom riflescope with the magnification of 5-25×, the entrance pupil diameter of 60 mm, and the reticle located in the first focal plane have confirmed the effectiveness of the proposed algorithm to design automatically complex multi-lens optical systems with variable parameters. The obtained results proved the high image quality of the generated 13-lens riflescope with the long eye relief. The implemented modification of the adaptive Cauchy differential evolution method can be considered a powerful tool that helps to automate the parametric synthesis of multicomponent optical systems of zoom riflescopes, taking into account the requirements set by the designer. Future research should test the feasibility of automated design of other riflescopes containing more lenses and providing extreme performances.