Design of high-resolution image square telecentric continuous zoom projection lens based on TIR prism

To meet the requirements of high-resolution, high-illuminance uniformity, long working distance and continuous zoom projection of engineering projectors based on TIR prisms, a new method for continuous zoom and high-resolution telecentric projection lens design was proposed. The focal length of the designed projection lens with F/2.4 ranged from 25 mm to 32 mm, and the lens was specialized for the visible light application. The properties of the large target surface, high-resolution, long working distance and good illumination uniformity were the main difficulties in the projection lens design. The double Gaussian model with anti-distance was chosen as the initial structure. Then a specialized control strategy for image telecentric was employed. The whole design process was conducted in CODE V associated with the expert automatic optimization strategies, such as the choice of the types of different glasses. The results show that the value of MTF within the view fields is no less than 0.4 at 72 lp/mm, the diameters of RMS diffuser is less than 8.5 m, the distortion is under 2%, and uniformity of field of view of the short focal edge is greater than 95%. The projection lens designed with spherical surfaces show the compact structure and well image quality. The key points, such as distortion, vertical axis chromatic aberration and illuminance uniformity, are also well controlled in this design, which demonstrates that the designed project lens can meet the requirements of high-resolution engineering projectors well.