Optical elements from 3D printed polymers

3D printing belongs to the emerging technologies of our time. Describing diverse specific techniques, 3D printing enables rapid production of individual objects and creating shapes that would not be produced with other techniques. One of the drawbacks of typical 3D printing processes, however, is the layered structure of the created parts. This is especially problematic in the production of optical elements, which in most cases necessitate highly even surfaces. To meet this challenge, advanced 3D printing techniques as well as other sophisticated solutions can be applied. Here, we give an overview of 3D printed optical elements, such as lenses, mirrors, and waveguides, with a focus on freeform optics and other elements for which 3D printing is especially well suited.