Zoom projection lens design for small throw ratio and large field of view

Abstract

In order to meet the requirements of large screen projection displays, we propose an ultra-thin zoom projection lens with a small throw ratio (TR), ultra-short throw distance and large field-of-view (FOV) using a digital micromirror device as a spatial modulator. A refractive–reflective system is developed to correct the distortion and shorten the projection distance. The image size (diagonal, 16:9 aspect ratio) of the projector is 80–120 in. (2.032–3.048 m) with a TR of 0.22, TV distortion < 0.6%, root mean square (RMS) spot size < 1.1 mm, relative illumination > 85% and modulation transfer function > 0.4 at 0.55 lp/mm for all fields and zoom conditions. When the tolerance error is considered, the RMS value is less than 1.3 mm for all fields and zoom conditions. Finally, the projection lens is fabricated and tested according to the designed model.