Methodology for the design of infrared objectives with homogeneous, gradient-index, and diffractive elements

Subject of study. This study was focused on simple-design infrared (IR) objectives, including either a single coaxial-laminated radial gradient-index (GRIN) lens or a combination of a GRIN lens and a diffractive optical element, in addition to homogeneous lenses. Aim of study. The aim of this study was to develop a methodology for the layout design and calculation of simple-design IR objectives with a hybrid element base. Method. The methodology included theoretical analyses, computer modeling, and optimization with the Zemax optical design software. Main results. The proposed methodology covers all stages of the layout design and calculation of the objective. It includes the selection of optical materials for all its elements, as well as recommendations for using the optical scheme obtained under the conditions of achromatization, apochromatization, or superchromatization as the initial scheme for subsequent optimization in Zemax. The methodology also provides guidelines for combining a GRIN lens with a diffractive optical element in the design and calculation of an ultra-high-speed dual-band gradient-diffractive objective. The effectiveness of the combined use of GRIN and diffractive elements and that of the proposed methodology are demonstrated through a calculation example of an ultra-high-aperture gradient-diffractive objective. Practical significance. The results of this study highlight the possibility of developing simple-design, high-aperture, dual-band IR objectives based on coaxial-laminated radial GRIN lenses.