Automatic compact-volume design strategy for unobscured reflective optical systems based on conicoid surfaces

Off-axis reflective optical systems are frequently large in volume to avoid obscuration, and their subsequent optimizations are complex and time-consuming, resulting in volume reduction while sacrificing surface shape complexity. Therefore, this paper proposes an automatic small-volume high-resolution reflective optical system design strategy based on joint aberration model and a global simulated annealing algorithm (SA). The method establishes a comprehensive joint aberration-based imaging quality and volume-constrained evaluation function. Under the premise of ensuring the imaging quality, the volume reduction of two off-axis three-mirror reflective optical systems with large fields of view (FOVs) has been achieved greatly: (1) the volume of the systems with off-axis FOVs was compressed to 22.7% of the conventional method; (2) the volume of the systems with a small F-number, decenter and tilt was compressed to 28.3% of the conventional method, successfully achieving the volume compression of the off-axis reflective optical systems, proving the feasibility and simplicity of this method. This method is more scalable, starting with a conical surface, which can well realize the transition from simple to complex surfaces, providing the choice and comparison of surface types and contributing to the rapid estimation of the system volume. •This manuscript proposes the establishment of a more comprehensive evaluation function and the adoption of a global optimization algorithm, which greatly improves the efficiency and accuracy of the design.•The design process of the reflective optical system reduces human intervention and weakens the dependence of the traditional optical design on experience.•The final two design examples achieved a volume reduction to 22.7% and 28.3% of the system designed by the conventional method, respectively. The convenient design method and effective design results prove its value for the designs of high-resolution and small-volume spatial optical systems.