Design and analysis of a linear astigmatism-free confocal off-axis reflective collimator for aerial applications

This paper presents the design and analysis of a linear astigmatism-free confocal off-axis reflective collimator for line-of-sight alignment in multi-wavelength/multi-field-of-view optical sensor modules. Comprising two off-axis mirrors and one flat mirror, the collimator has a 73 mm entrance pupil diameter and a 1200 mm focal length. Sensitivity analysis and Monte Carlo simulations using Optic Studio (ZEMAX) confirmed that the design meets all specified requirements. Stray light analysis shows that stray light is effectively blocked by the optomechanical structures only, eliminating the need for additional baffle structures. A semi-kinematic mount ensures assembly precision, while modal analysis indicates a fundamental frequency of 232.55 Hz, ensuring durability in aerial operations.