Freeform Optics for Achieving Collimated and Uniform Light Distribution in LCD-Type UV-Curable 3D Printing

Ultraviolet light (UV)-curable three dimensional (3D) printing has emerged as a prominent additive manufacturing technology, finding diverse applications in industries such as figurine production, artifact restoration, dentistry, jewelry design, and etc. For liquid crystal display (LCD) type UV-curable 3D printers, achieving a uniform and collimated light distribution of the illumination system holds paramount importance, as it directly influences printing precision. This study proposes a novel light tailoring method employing freeform lenses to attain high efficient illumination system for 3D printers. The proposed illumination system mainly comprises a high-power UV LED, a freeform lens, and a Fresnel lenses. Initially, a ray mapping between the source domain and the target domain is established to design the preliminary freeform lens, assuming a point-like light source. Subsequently, considering the physical dimension of the high- power UV LED, the preliminary lens is further optimized to generate a uniform illuminance distribution in a rectangular shape. Finally, a Fresnel lens is employed to collimate the light. The results demonstrate a full width half maximum of the angular distribution of less than ±5°, indicating a narrow spread of the light beam. The illuminance distribution within the specified domain exhibits an impressive level of uniformity, exceeding 90%.