Researchers at Lawrence Livermore National Laboratory have used multi-material 3D printing to create glass optics that could lead to better specialized military eyewear and virtual reality goggles.

LLNL said gradient refractive index optics produced by the 3-D printing techniques can have a flat surface yet still perform the same optical functions as a conventional curved lens, offering new design versatility.

Multiple capabilities could also be designed into a single optic, such as focusing with correction of common optical aberrations.

By tailoring the index, a curved optic can be replaced with a flat surface, which could reduce finishing costs. Surface curvature also could be added to manipulate light using both bulk and surface effects.

The new technique also can save weight in optical systems. For example, it’s critical that optics used by soldiers in the field are light and portable.

The research team was able to tailor the gradient index by controlling the ratio of two different glass-forming pastes or “inks.” After the optical preform is created using Direct Ink Writing, it is “densified” to glass and finished using conventional optical polishing.

“The change in material composition leads to a change in refractive index once we convert it to glass,” said LLNL scientist Rebecca Dylla-Spears, lead author of a paper appearing in Science Advances.

“This is the first time we have combined two different glass materials by 3D printing and demonstrated their function as an optic,” Dylla-Spears said.