Chameleonic cube corners

Abstract

A retroreflector construction comprises a first transparent layer of a relatively high refractive index having on its rear surface one or more cube corner retroreflector elements; a second thin transparent layer of relatively low refractive index in substantially uninterrupted contact with the rear surface of the first layer; and a third metallic reflective layer in substantially uninterrupted contact with the rear surface of the second layer. The ratio of the indices of refraction of the two transparent layers is sufficient to allow TIR at their interface for at least some of the cube faces. The third, metallic layer assures face reflection when TIR fails. The construction provides greater retroreflectance than would be achieved with a single metallized transparent layer, and provides retroreflectance over a broader range of entrance angles and orientation angles than would be achieved with a single non-metallized (air-backed) transparent layer. The construction provides a greater structural integrity than can be achieved with air-backed construction. The front surface of the first transparent layer optionally may be provided with a transparent overlay. A method of making the retroreflector is also disclosed.

Dependencies are inferred from the claim text.