An imaging system for a three-dimensional printer includes a light source component, at least one pattern determining element, a light splitter, a light directing component, and a lens component. The light source component emits a first light and a second light having different wavelengths. The pattern determining element provides the first light and the second light with a first pattern and a second pattern respectively. The light splitter directs the first light and the second light to different directions respectively. The light directing component guides at least one of the first light and the second light, such that the first light and the second light go to a first plane and a second plane respectively. The lens component includes a first lens group and a second lens group, configured to image the first pattern and the second pattern onto the first plane and the second plane respectively.