Freeform reflection imaging system design based on subaperture integrating method

• Novel construction design method for freeform imaging optical system. • Based on concept of subaperture, the construction relationship of this method is closer to real-world situation. • Achieve a fast design speed. • Two reflection design examples by this method is introduced. We introduce a novel design methodology for freeform reflective imaging systems based on the integration of multiple subapertures. Subapertures are systems with the same aperture as the designed system but only a relevant small field of view (FOV). The method is based on the premise that each subaperture can retain excellent local characteristics within its designated FOV. By assembling these subapertures, we are able to design complex optical systems that achieve high performance with a wide FOV. During the design process, the reflective surfaces of the freeform reflective imaging system are constructed by combining the sampling points of many subapertures and the corresponding normal vectors of these sampling points, to maximize the retention of local characteristics of each subaperture in the combined freeform system. This method can converge at a relatively fast rate compared with traditional design method. The designed optical systems based on the proposed method exhibit good performance and can serve as superior starting structures for further optimization. Furthermore, Practical examples presented validate the effectiveness and practical applicability of our methodology.