Long-term performance of 3D-printed optics when exposed to thermal and optical radiation

Vat photopolymerization and multi-jet modeling 3D printers using clear polymer resins have shown promise for making optically clear lenses for LED lighting systems. These clear resins are usually polymethyl methacrylate, acrylonitrile butadiene styrene, and polycarbonate-like photopolymers. One of the main requirements for such lenses in LED lighting systems is stable performance, i.e., maintaining transmitted light and chromaticity for an extended period (over 25,000 hours). A long-term aging study was designed and conducted to understand light transmittance properties as a function of time. The 3D-printed lens samples were exposed to elevated ambient temperature (~45 and 60°C) and short-wavelength optical irradiance (~0.20 and 0.4 W/cm²) with peak wavelength radiation ~450 nm and FWHM ~25 nm. Test samples were 3D-printed using three clear transparent resins and using vat photopolymerization and multi-jet modeling processes. The lens samples were removed from the aging setup at regular intervals and the transmittance was measured at room temperature. The measured time to 90% lumen maintenance (L90) and 70% lumen maintenance (L70) were affected more by optical irradiance change from 0.20 W/cm² and 0.4 W/cm² than ambient temperature change from 45°C and 60°C. The vat photopolymerization 3D-printed test samples used for the study showed higher relative transmittance degradation than the multi-jet modeling test samples used in the study for both irradiances and ambient temperatures.