基于复合变焦光学系统原理,提出了一种新型复合变焦光学系统结构。该结构将连续变焦与两档变焦结合,可以增大变焦光学系统的焦距变化范围,实现更大的搜索范围和更远的跟踪距离。建立了新型复合变焦系统光学设计的数学模型。在该模型的指导下,针对像元数为320×240,像元尺寸为30 μm×30 μm的长波红外非制冷焦平面探测器,设计了一款新型复合变焦光学系统。该系统工作波段为8~12 μm,焦距变化范围为10~360 mm,在10~60 mm时,F数为2,在60~360 mm时,F数为4。对光学系统凸轮曲线和性能进行了分析。结果表明,该系统具有变倍比大、结构简单、像质好和变焦轨迹平滑等优点,验证了该数学模型的有效性。

Based on the principle of compound zoom optical system, a new compound zoom optical system structure is proposed. The structure combines the continuous zoom system with the two-step zoom system to increase the focal length range of the zoom optical system and achieve the larger search range and the longer tracking distance. A mathematical model of optic design of the new compound zoom system is established. Under the guidance of this model, a new compound zoom optical system is designed for long wave infrared uncooled focal plane detector with pixel number of 320×240 and pixel size of 30 μm×30 μm. The working band of the system is 8~12 μm, the focal length range is 10~360 mm, the F number is 2 at 10~60 mm, and the F number is 4 at 60~360 mm. The cam curves and performance of the optical system are analyzed. The results show that the system has such advantages as large zoom ratio, simple structure, good image quality and smooth cam curves, all of which verify the validity of the mathematical model.