Design method of dual-band synchronous zoom optical system based on co-path zoom groups

The dual-band zoom imaging system has great application value in military and civilian fields with the advantages of a large field of view (FOV) search, long-range tracking, camouflaged target reconnaissance, and all-day operation. To address the problem of synchronous zoom in dual-band co-aperture zoom optical systems, a dual-band simultaneous zoom optical system design method based on the co-path zoom groups is proposed. This optical system can realize zooming simultaneously in visible (VIS) and shortwave infrared (SWIR) bands and effectively control the total length. We first analyze the synchronous zoom principle of the dual-band co-path zoom optical system, then we propose a joint solution method for solving the initial structure of the dual-band zoom optical system. After obtaining the initial structure parameters, we performed the real-lens replacement and aberration correction in Zemax. Finally, a dual-band co-path simultaneous zoom optical system with working bands of 900∼1700 nm and 480∼660 nm, and zoom ranges of 10∼150 mm and 100∼150 mm, respectively, was designed. The focal length difference of the dual-band optical system is less than 0.16% during the simultaneous zooming process, and the system also has the advantages of good imaging quality, compact structure, simple zoom structure, and smooth cam curve.