J.D. Engelhardt, J.F. Stanzione, R.V. Chimenti
Rowan University,
United States
Keywords: GRIN Lenses, 3D Printed Optics, Optics Manufacturing
Summary:
Refractive index dictates the bending power of a material and in the case of graded index (GRIN) optics, the refractive index varies spatially throughout the volume of the lens. Traditional methods of manufacturing GRIN lenses, such as chemical vapor deposition, ion exchange processes, and neutron irradiation, are time consuming, labor intensive, and cannot yield custom refractive index profiles. Additive manufacturing (3D printing) methods provide a potential alternative route to produce polymeric GRIN lenses easier and reduce costs as well as enabling the production of entirely new optical components. Recently we have demonstrated the ability to print GRIN lenses by judicious use of partial polymerization. This process allows one to manipulate the refractive index, creating polymeric GRIN optics without the need for dopants or multi-material formulations. This is accomplished by parametric analysis of both reactive bond concentration and index of refraction kinetics during polymerization, combined with a previously developed vat photopolymerization conversion prediction model. With this model, flat faced GRIN lenses can then be produced using digital light projection technology. Using the correlation between conversion and refractive index, the printed optic can then be characterized and analyzed by measuring the actual conversion, as compared to the expected conversion. This work provides a pathway towards the manufacture of freeform GRIN optics with arbitrary 3D index of refraction profiles.