A composite optical film comprises a first optical film and a second optical film disposed on the first optical film, wherein the first optical film comprises a first substrate; a plurality of reversed prisms disposed on a bottom surface of the first substrate; and a first diffusion film disposed over a top surface of the first substrate; and the second optical film comprises a first PET film thereon having a first set of prisms and a second PET film having a second set of prisms thereon, wherein the first PET film and the second PET film are laminated together.