Calculation automation of “cemented doublet with a singlet” and “singlet with a cemented doublet” objectives

Abstract

Subject of study. Automating the synthesis of “cemented doublet with a singlet” and “singlet with a cemented doublet” objectives with an entrance pupil on the first surface of the system is studied. The design of this type of system is complex owing to a large number of possible solutions. Moreover, when changing over from an infinitely thin system to a system with a finite thickness of elements, the image quality of axial points significantly deteriorates in most cases. This feature should be considered when developing an algorithm for lens design. Aim of study. The aim is to develop a method and algorithm for automatic synthesis of “cemented doublet with a singlet” and “singlet with a cemented doublet” objectives and a ranking system for designed objectives. Changes in the axial point image quality of the considered objectives with two or three different materials for possible acceleration of the synthesis process are also studied. Method. The initial design of objectives is carried out on the basis of the third-order aberrations theory. An automated exhaustive search is used to rank all possible combinations of lens materials. Main results. The methodology and algorithm of the automatic design of “cemented doublet with a singlet” and “singlet with a cemented doublet” objectives have been developed. A ranking system is provided to rank the designed objectives by the main criterion based on the axial point image size and by the preliminary criterion that determines the technological stability of the objective to the manufacturing errors of the optical elements. It is determined that the “singlet with a cemented doublet” objectives are generally preferable to “cemented doublet with a singlet” objectives according to the proposed criteria. Based on the calculation results, it is demonstrated that solutions with only two materials can have a slight decrease in the image quality of the axial point. Practical significance. Based on the developed algorithm, the program for the automatic design of two- and three-lens objectives is upgraded. The developed program will help optical engineers to significantly simplify and accelerate the process involved in designing two- and three-lens objectives with the required image quality characteristics.