Hartmannometer and Fizeau interferometer: comparative analysis of optical-surface testing devices

Subject of study. This study proposes an optomechanical device as an alternative to a Fizeau interferometer for optical-surface quality control. Aim of study. The aim of the study was to develop and assess a metrological device for measuring optical-surface flatness and to compare the measurement results obtained with this device against those from a Fizeau interferometer. Method. The wavefront of the radiation reflected from the tested optical surface is measured using a Shack–Hartmann sensor. Main results. This research developed a fundamentally new device, named a Hartmannometer. A method for its calibration is introduced, and a comparison is made between the measurements of a test optical surface using both the developed device and a conventional Fizeau interferometer. The total wavefront-distortion amplitude measured using the Fizeau interferometer was 0.127 µm (root mean square deviation of 0.022 µm), while the Hartmannometer showed a total distortion amplitude of 0.131 µm (root mean square deviation of 0.024 µm). Practical significance. The developed device may serve as a more reliable and cost-effective alternative to the Fizeau interferometer for tasks related to the quality control of optical surfaces.