Additive manufacturing, or 3D printing, is particularly attractive for the fabrication of flat freeform optics. These differ from conventional optics in that they do not rely on the geometry of the lens to guide light. Instead, flat freeform optics exploit a change in refractive index by spatially varying the percent of dopant, in this case GeO2. The ability to conveniently fabricate flat-refractive index graded optics would be paradigm shifting, allowing for more compact optical design and reduced wavefront loss. In this presentation, we report the preparation of sol-gel derived GeO2-SiO2 core-shell particles that can be formulated into an ink for use in direct ink write 3D printing glass optics. Results discussed will include efforts to prepare GeO2 core and GeO2-SiO2 core-shell particles which have are both small (sub-100 nm in diameter) and colloidally stable. The role of varying the ratio of water, catalyst, and solvent to the GeO2 precursor, as well as the reaction temperature will be discussed. For glass production, we show the prepration of transparent and semi-transparent glasses over the range of 5 to 25 wt% GeO2 dopant. Ongoing studies include the chemical characterization of the core and core-shell particles at various stages of particle growth and glass formation.

Preparation of sol-gel GeO2 and GeO2-SiO2 nanoparticles for use in 3D printed optics

2019 Spring National Meeting

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