Brightness Enhancement Film (BEF) is widely used in the design and manufacture of LCD screens and large-screen TVs. It is generally used to provide maximum brightness towards the on-axis viewer.

BEF uses a microreplicated prismatic structure to control the exit angle of the light. In this schematic diagram, rays from the source may undergo multiple total internal reflections, before emerging at close to on-axis angles with respect to the viewer. More details can be found here. Light within the viewing cone (approxinately 35° off the perpendicular) is transmitted out and light outside this angle is TIRed back into the film and recycled until it is within this cone angle.


In this article we will model the Vikuiti™ Thin Brightness Enhancement Film (T-BEF) 90/24 microreplicated prism film. From the manufacturer's datasheet, the nominal film properties are:

Thickness: 62µ
Prism Angle: 90°
Prism Pitch: 24µ