Design of wide-angle projection lens for 4k digital projector

To meet the need of 4k short distance movie projection, a wide-angle projection lens was designed, which is suitable for projectors with threedigitalmicromirror-device (DMD) chips. The largest projection ratio could be 0.75∶1, the relative aperture is 1/2.2, the inverted telephoto ratio is 4.6∶1. At the Nyquist frequency of 66lp/mm, the resolution of center field is 0.42,and the resolution of marginal field is 0.25. The max lateral chromatic aberration is 3.7 m, which is less than 0.5 pixel, and the max distortion is 2.5%. The feature of inverted telephoto was deeply analyzed, and the methods for choosing structure, distributing focal power and calculating key parameters were provided in the paper, additional, the issues needing pay attention during aberration correction were contained. Finally, a wide-angle projection lens with high resolution which could meet all the indices was designed, besides that, the lens has the feature of easy structure, low cost and high quality.