Technology for developing a high-aperture four-mirror lens with aspherical mirrors

Abstract

Subject of study: Methods for optimizing the design, assembly, and alignment of a high-aperture wide-angle four-mirror axisymmetric lens are presented. Aim of study: The aim is the development of a high-tech lens design considering the relationship between the calculated tolerances for the decentering of mirrors and the technological capabilities of their fabrication, assembly, and alignment. Method: The methods include selection of an image quality criterion and calculation of its permissible decrease, distribution of the fabrication errors between the decentering errors and surface shape errors, and calculation of the tolerances based on the obtained ratios. Moreover, the motivation for choosing a lens design with a minimum number of adjustment stages based on the optimization of the calculated permissible decentering is provided considering the technological tolerances for positioning the optical elements. In addition, the possibilities of the scheme to compensate for the residual aberrations resulting from the fabrication and positioning of the mirrors are investigated. At the final stage, the method of reducing the evaluation function for the final adjustment of the optical elements in the lens is used. Main results: The design and technological solutions enabling the optimization of the requirements for the tolerances for deviation of the surface shape of the mirrors from their calculated profile, as well as decentering of the optical elements considering the technological capabilities of production, are examined. The criteria for the distribution of tolerances for permissible deviations of optical system parameters affecting the image quality are formulated. The possibility of designing a high-tech drop-in structure of a high-aperture four-mirror lens comprising a case of two blocks and a single linear adjustment stage of the second mirror to compensate for residual aberrations is demonstrated using the proposed method. Practical significance: The proposed technical solutions were tested by designing a high-resolution lens comprising four aspherical mirrors. The positive results of fabricating a lens with a high aperture and resolution allow the proposed solutions to be used for the design of multimirror axisymmetric lenses.