Sulfur polymer for high index wide field of view (WFOV) diffusers for 3D scanning applications

Rapid advancements in consumer electronics, assisted driving, and robotics require state-of-the-art 3D scanning devices. 3D scanning techniques are becoming lower cost, lighter, and have a wider field of view, due to the use of lens-less polymer diffuser devices. In this paper, we model and demonstrate the use of the sulfur polymer material (S-NBD2) as a moldable, high index material for diffuser fabrication. Elemental sulfur is a byproduct of crude oil production as well as mining extraction processes. It exists in nature as a ring of eight atoms. When heat is applied to this ring, it breaks into a chain, and this chain can be used to make a sulfur polymer through the inverse vulcanization process. Sulfur polymers have a high refractive index and high transmission at long wavelengths, which is very promising for sensing in infrared spectral regions. They can easily compete with bulky, expensive existing materials such as calcium fluoride, zinc selenide, and sapphire. Sulfur polymers are made from materials that are lower cost and easier to obtain, since elemental sulfur generally is discarded into giant heaps at oil refineries. Sulfur polymers are also straightforward to compression mold, and they cure at high temperatures (∼ 160°C). Overall, sulfur polymers, with attributes such as high index of refraction, high IR transparency and moldability, are ideal candidates for wide field of view (WFOV) diffusers and other optical components for passive sensing devices.