Development of an optical system for an autocollimation tube with digital image registration for testing the centering of single lenses

Subject of study. The optical design of an autocollimation tube for measuring lens decenter is investigated. Aim of study. The aim is to develop a compact optical system for measuring the decenter of single lenses, to estimate the measurement error while accounting for the characteristics of the optical system and the use of simple image processing methods, and to analyze the factors influencing measurement accuracy. Method. In the proposed system, the image formed by a surface with a known decenter is modeled within the framework of geometrical optics. The centroid of the intensity distribution is determined using the center-of-mass algorithm, and then used to calculate the decenter of the lens surface. Main results. A compact optical system for lens decenter testing has been developed. The reasons for increased measurement error for lenses with small radii of curvature (20 mm or less) are analyzed in detail. A systematic error affecting the accuracy of decenter determination is identified. After accounting for optical system aberrations, digital image registration, image processing, and the identified systematic error, the residual error in decenter measurements does not exceed 1 µm. Practical significance. The proposed optical scheme can serve as the basis for a production instrument integrated into optical manufacturing equipment. The analysis of error sources in the lens decenter testing system, as well as the applied modeling and processing techniques, is of practical interest for the development of modern high-precision instruments.