Development of single-sided structure collimation film for direct-lit collimated backlight module

In this paper, we proposed an optical structure to enhance the collimation and uniformity of 405 nm LED backlight modules. The structure is called a single-sided structure collimation film (SSSCF), which consists of a lenticular lens array, slit apertures, and a highly reflective coating surface. A lenticular lens array with slit apertures converts the angle of diffusive incident light into collimated light. The high-reflective coating of the collimation film can reflect back the light that does not enter the slit aperture to the backlight module for energy recycling. Finally, we have developed a direct-lit backlight module with optimized collimation properties (FWHM = ±3.4°, gain = 2.3%, NSR = 0) and great uniformity (uniformity > 83.5%). We also demonstrated good consistency between our simulation results with optical measurement. The collimated backlight module developed in this study has great potential for future applications, including high-precision 3D printing objects, liquid crystal displays with high contrast ratio or narrow viewing angles, and telecentric illumination devices used in precision machine vision systems.