An illustrative refrigeration unit door includes a transparent window portion that receives light from a light source such that the light exhibits total internal reflection within the window portion. A series of uniformly-sized prisms with non-uniform spacing ejects light from one face of the transparent window portion at angles around 60 degrees and 30 degrees. Collimated light can be used to reduce the amount of light ejected from a second face of the transparent window that is opposite the first face.