3D printed diffractive lenses operating at 1 THz
In this paper, we demonstrate the manufacturing of diffractive optics for frequencies as high as 1 THz using a relatively simple and cost-effective fused deposition modelling (FDM) 3D printing technique. Four diffractive lenses were designed and manufactured from the cyclic olefin copolymer (COC). Fabrication of diffractive lenses for such high frequencies was possible due to an unusually small nozzle, refined printing procedures and a very transparent material. For the two of the manufactured lenses, more than twofold improvement in focusing efficiency has been shown in a direct comparison with their refractive counterparts. Moreover, the other two elements demonstrated the feasibility of lenses with very small f-numbers (0.95 and 0.63) with this technique.