A brightness enhancement film includes a substrate and a plurality of curved prism units. The curved prism units are extended in parallel and mounted to a surface of the substrate. Each of the curved prism units includes at least one meandering surface to provide with changes in curvature. Thus, the meandering surface of the curved prism unit is able to refract incident light in two dimensions with respect to the substrate that may enhance entire refractive efficiency in two dimensions.

 
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< Illumination optical system, illumination unit and image projection apparatus employing the same

> Light source module and projection display having the same

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