Patent ID: 8248691

Claim:
An infrared light transmission film comprising: a polymer matrix and at least one red colorant, blue colorant, and yellow colorant that are uniformly dispersed in the polymer matrix at amounts effective to allow transmission through the film of at least about 85% of light with wavelengths over about 800 nm while blocking transmission of at least about 90% of light with wavelengths less than about 750 nm, wherein the film is disposed on a retroreflective layer having a plurality of retroreflective elements, and wherein the red colorant is provided in the film at an amount of about 0.3% to about 4% by weight of the film, the blue colorant is provided in the film at an amount of about 0.1% to about 0.4%, by weight of the film, and the yellow colorant is provided in the film at an amount of about 0.1% to about 0.6% by weight of the film.