Abstract: Lighting devices are disclosed that include a light source, a linear reflective polarizer optically coupled to the light source, a back reflector configured and disposed to reflect light that has been reflected by the linear reflective polarizer back toward the input surface thereof, one or more optical elements having a total non-zero retardance Rs and disposed between the linear reflective polarizer and the back reflector, and a customized retarder. The customized retarder has a retardance Rc such that a total retardance of the one or more optical elements and the customized retarder, Rs+Rc, approaches ?/4+n ?/2. The one or more optical elements, the customized retarder and the back reflector are characterized by a total depolarization of no more than 66%. Display devices including such lighting devices are also disclosed.

Abstract: Lighting devices are disclosed that include a light source, a circular reflective polarizer optically coupled to the light source, a back reflector configured and disposed to reflect light that has been reflected by the circular reflective polarizer back toward the input surface thereof, one or more optical elements having a total non-zero retardance Rs and disposed between the circular reflective polarizer and the back reflector, and a customized retarder. The customized retarder has a retardance Rc such that a total retardance of the one or more optical elements and the customized retarder, Rs+Rc, approaches n?/2. The one or more optical elements, the customized retarder and the back reflector are characterized by a total depolarization of no more than 66%. Display devices including such lighting devices are also disclosed.

Abstract: A contact sensitive device includes a member capable of supporting bending waves and a plurality of sensors mounted on the member for measuring bending wave vibration in the member. The sensors measure the bending wave signals and by calculating a phase angle for each measured bending wave signal and a phase difference between the phase angles of least two pairs of sensors so that at least two phase differences are calculated, the location of the contact can be determined.