Design of large aperture zoom projection lens

In order to obtain a large aperture zoom projection lens after optimizing a large aperture fixed focal length projection lens as the initial structure, a reasonable initial structure of fixed focal length lens was selected.According to DMD diagonal size, the dimension mapping of initial structure was done using AUTOCAD, the material of each lens was initially selected, and 5 zoom components were programmed in this system. The design was carried out by limiting the basic parameters and dimensions of lens with various operations, and 2 aspheric surfaces were used reasonably. After the optimization by using the optical design software ZEMAX and CODE V, a zoom projection lens system in visible light band was obtained. The system has a short focal length of 14.61 mm with 60° field of view(FOV) and 1.5 F number, while it has a long focal length of 29.31 mm with 30° FOV and 1.6 F number. The design results show that the modulation transfer function (MTF) of each FOV at each focal length is not less than 0.46 at the cut-off frequency 60 lp/mm. The dispersion angle at each focal length is not more than 1.6'. The projection lens achieves high quality of image. This lens system consists of 11 pieces of lenses and 1 piece of parallel plate, and the lens 2 uses aspheric surface. The system has less chips of lenses with low refractive index, and the material of each lens is easy to choose.