An imaging homogenizer for DLP-based 3D printer

Abstract

A compact imaging Köhler homogenizer with adjustable flattop size was implemented for a DLP engine. It is composed of pulsed UV LED, collimator aspheric lens, double-sided micro-lens array (MLA) with 34×15 micro-lenses and 0.8mmx1.76mm pitch size, and condenser lens. The homogenizer is dedicated for DMD chip of size 1920×1080 pixels (4K resolution) for 3D printer application. The produced flattop at the DMD has 98% measured uniformity and 85% optical efficiency. The calculated Fresnel number was greater than 60, indicating that our MLA has low diffraction effects. A lowcost RTIR prism was proposed using a wedge and a right-angle prism. Compared to conventional RTIR, the structure characterized by low cost and simplicity in assembly.