Design of high-resolution long working distance double-telecentric projection lens

In order to improve the accuracy of products fabricated by projection micro-stereolithography technology based on DMD, a high-resolution projection lens with double-telecentric structure and long working distance is designed in this paper. Before the design of projection lens, several parameters should be set first according to design requirements. Then, a grouping design method is proposed to design the initial structure of double-telecentric projection lens. With the help of ZEMAX, the initial structure is optimized to the ideal structure when all parameters are close to the target value. The simulation results show that the designed projection lens has a resolution of 1 μm in X-Y within 6 μm thickness of curable layer in Z axis. Meanwhile, it can be seem from the final projection lens that telecentricity at the whole field of view of object-side and image-side are 0.42° and 0. 43° respectively and working distance at object-side and image-side are 64mm (including the thickness of TIR prism)and 6. 5mm respectively. The projection lens designed with spherical surfaces show the well image quality, small telecentricity and long working distance, which indicates that the projection can be widely used in 3D printer of projection micro-lithography technique based on DMD.