Brightness enhancement film using a linear arrangement of light concentrators

An illumination system comprising:

• (a) a light providing element having an output surface;
• (b) a brightness enhancement article comprising a plurality of light collecting structures, wherein each light collecting structure is longitudinally extended in a length direction along the output surface of the light providing element, each light collecting structure comprising:
• (i) an input aperture optically coupled to the output surface of the light-providing element;
• (ii) an output aperture distal from the input aperture, wherein the output aperture has a surface area that is larger than the surface area of the input aperture;
• and,
• (iii) a pair of curved side walls extending from the output aperture toward the input aperture;
• wherein, in a cross section taken orthogonally with respect to the length direction, the curved side walls approximate a parabolic curvature;
• (c) a reflective surface, along at least a portion of the surface of the light providing element opposite the output surface, for reflecting light back into the light providing element;
• and,
• (d) a prism surface optically coupled with the surface of the light providing element and opposite the output surface, the prism surface comprising prism structures longitudinally extended in a width direction, the width direction being substantially orthogonal to the length direction of the brightness enhancement article.