Non-telecentric projection lens design for an LED projector

Abstract

A newly designed non-telecentric projection zoom lens is proposed for a mini-projector with LED light sources. The projection lens consists of six spherical lenses. The zoom ratio of the projection lens is 1.1. At the wide condition, the working F/# can maintain at 2.4 and the throw ratio can operate at 1.23. The root mean square (RMS) spot sizes of all fields are smaller than 15 mu m for all zoom ranges. The optical distortion and the TV distortion were suppressed to be smaller than 1.5% and 1%, respectively. For the image quality issue, the modulation transfer function (MTF) value for all fields is above 0.4 at 46 lp/mm for all zoom conditions. Even when the tolerance error was considered, the MTF value for all fields is still above 0.3 for all zoom conditions. Using this non-telecentric projection zoom lens, a very sharp image could be achieved with low cost. This low cost projection lens is very suitable for business applications. (C) 2017 Optical Society of America