Roll-to-Roll Process-Based Sub-Wavelength Grating for a Color-Separation Backlight

For this study, we designed a color-separation backlight to avoid the use of absorptive color filters in a conventional backlight. The module consists of sub-wavelength grating on a light-bar (SWG-LB) and a cylindrical lens array on a V-grooved light guide to display R/B/G images more efficiently. We designed the light bar to be a hexagon type in which partial total internal reflection (TIR) area is uniformly spaced between each SWG. The measurements showed that uniformity from the light bar and NTSC are 92.8% and 99%, respectively. The optical components including the sub-wavelength grating and the cylindrical lens array were mass produced, and the diamond turning was produced using a roll-to-roll process.