UVA, B, and C Glass Optics Designed to Mix Wavelengths, Increase Irradiance, and Improve Uniformity: Design, Simulation, and Analysis
Brian S. Jasenak, Kopp Glass
Abstract: Due to the common practice of using multiple LEDs in an array and their directional nature, striping can occur when the spacing between LEDs in the array causes irregular energy distributions on the incident light surface.
Flat panes of fused quartz, silica, or glass are commonly used to cover and protect multi-UV LED arrays. However, they don’t offer the advantages of an optical lens design. An investigation was conducted to determine the effect of a secondary glass optic on the uniformity of the light distribution and irradiance. Glass optics capable of transmitting UV-A, UV-B, and UV-C wavelengths can improve light distribution and intensity and prevent uneven curing.
In this study, a UV transmitting glass formulation and secondary linear optic were designed and manufactured to demonstrate their effects on achievable irradiance intensity and uniformity. Prismatic patterning on the light source surface of the lens was used to minimize reflection losses on the incident surface of the glass. Fresnel optics were molded into the opposite side of the UV transmitting glass to control the refraction of the light and to gain the desired light intensity distribution from two multi-UV LED arrays. A 20% increase in relative irradiance was observed while maintaining the same coverage area. This talk will discuss the optical design and the resulting benefits of controlled light output on UV LED curing systems, which include reduced driving current, decreased thermal deterioration, improved energy efficiency, and longer LED lifetime.