Design of fog transmission lens with large continuous zoom range

In order to meet the needs of large-scale and long-distance monitoring, a 50 mm～750 mm fog transmission zoom lens is presented in this paper. The lens adopts a mechanical compensation zoom structure, and an ultra-low dispersion lens is used to correct the issue of large secondary spectrum at the telephoto end. The image quality of the lens is optimized by adjusting the initial structure and using the optimization operand. After optimization, the entire system consists of 18 spherical lenses with a total length of less than 360 mm. Design results show that MTF is close to the diffraction limit (MTF>0.2) under the condition of 130 lp/mm, and the RMS spot radius is less than 5 μm under the condition of the central field of view. The field curvature is less than 0.1 mm, and the distortion is less than 1%. The movement curve of the zoom group and the compensation group is drawn, and the curve is smooth without breakpoints. The system meets the actual application requirements of large-scale and long-distance fog monitoring scenarios, and has certain reference significance for the design of a large zoom optical system.