Digital optical measurement system with multielement marks

Subject of study. The possibility of utilizing array elements in angular metrology was investigated. The main focus of the study was to consider two-dimensional multielement marks of various types utilized in a photoelectric auto-collimator with a photodetector array. Aim of study. The study aimed to identify the shape of two-dimensional multielement marks that enable the minimization of errors in determining their centers. Method. The study mainly focused on the results of the development of autocollimators with multielement marks in the form of a circle or set of concentric rings. An algorithm for determining the coordinate of the mark image based on the calculation of the geometric center of the image was proposed and implemented. The algorithm for calculating the coordinate of a mark image involves obtaining the interpolation polynomial for all gradients of the mark edge brightness. Main results. Errors in calculating the coordinate of the mark center based on the geometric center algorithm were obtained via simulations for different diameters of marks, both for the marks in the form of a circle and a set of rings. The optimum sizes of the marks of both configurations were estimated. An autocollimator was calibrated using both types of marks and a rotation table with an angle sensor. Autocollimator calibration using a multiele-ment ring mark and photodetector matrix with a pixel size of 3.45 mu m demonstrated an error in the range of +/- 0.0100 in the measurement range of +/- 60000. Practical significance. Application of the proposed configurations of multiele-ment marks enables a significant reduction in the range of error of photoelectric autocollimators.(c) 2023 Optica Publishing Group