US Patent 9575317 Optical guide suitable for creating two luminous imprints

An optical guide comprises at least one guiding element adapted for enabling, by total internal reflections, transporting an image taking the form of a collimated light beam from an injection zone to an extraction zone where an extracting device for extracting the image is mounted. The optical guide comprises a retardation plate and a polarization beam splitter, the polarization beam splitter being placed between the guiding element and the extracting device. The optical guide is such that each ray of said collimated light beam striking the polarization beam splitter for the first time separates into two portions, a first portion being transmitted to the extracting device so as to define a first light imprint and a second portion being reflected by the polarization beam splitter, said second portion continuing to be guided by the guiding element and thus passing twice through the retardation plate before striking the polarization beam splitter so as to define a second light imprint.