Researchers created tailored gradient refractive index glass optics using multi-material 3D printed glass, which could lead to better military-specialized eyewear and virtual reality goggles.
The new technique could perform a wide range of conventional and unconventional optical functions in a flat glass component (with no surface curvature), allowing for greater optical design versatility in environmentally stable glass materials.
The team was able to tailor the gradient in the material compositions by actively controlling the ratio of two different glass-forming pastes or “inks” blended inline for the 3D printed glass using the direct ink writing (DIW) method. After constructing the composition-varying optical preform with DIW, it is densified to glass and can be finished with conventional optical polishing. The refractive index changes when the material composition changes. Because additive manufacturing allows for the control of structure and composition, it has opened up a new avenue for producing gradient refractive index glass lenses.
Optics with a gradient refractive index (GRIN) offers an alternative to conventionally finished optics. The spatial gradient in material composition in GRIN optics provides a gradient in the material refractive index, altering how light travels through the medium. A GRIN lens can have a flat surface figure while performing the same optical function as a conventional lens of equivalent size.
Because of the evolution of eye lenses, GRIN optics already exist in nature. Most species have examples where the concentration of structural proteins governs the change in refractive index across the eye lens.
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