Low profile image combiner for near-eye displays

Abstract

An image combiner, also referred to as a combiner optic, of a near-eye display system or the like transmits enough light so a user can see remote objects in a “world view”, while also reflecting enough light so the user can simultaneously see a projected image in a “projected” (augmented) view. The disclosed image combiners use two partial reflectors configured to form a wedged reflective cavity. In the display system, light from an imaging device follows a path to the user's eye that includes three reflections in the wedged cavity. By using this capability of the wedged cavity, the combiner optic can have a substantially reduced thickness, and lower profile, than a combiner optic that uses only one partial reflector and only one reflection in the optical path.

1 . A system comprising first and second partial reflectors facing each other and defining a reflective cavity therebetween, at least one of the first and second partial reflectors being curved, one of the first and second partial reflectors being a notched reflector having distinct spaced apart blue, green and red reflection bands. 
     
     
         2 . The system of  claim 1 , wherein the first and second partial reflectors are both curved. 
     
     
         3 . The system of  claim 1 , wherein one of the first and second partial reflectors is a reflective polarizer. 
     
     
         4 . The system of  claim 3 , wherein the reflective polarizer is a linear reflective polarizer. 
     
     
         5 . The system of  claim 3 , wherein the reflective polarizer is a circular reflective polarizer. 
     
     
         6 . The system of  claim 1 , wherein one of the first and second partial reflectors comprises a metal coating. 
     
     
         7 . The system of  claim 1 , wherein for visible light, at least one of the first and second partial reflectors has an average reflectivity in a range from 25% to 75%, and an average transmission in a range from 25% to 75%. 
     
     
         8 . The system of  claim 1 , wherein a full width at half maximum (FWHM) of at least one of the distinct spaced apart blue, green and red reflection bands is less than 100 nanometers. 
     
     
         9 . The system of  claim 1 , wherein at least one of the first and second partial reflectors has a reflectivity at normal incidence that is substantially insensitive to polarization state. 
     
     
         10 . The system of  claim 1  further comprising a retarder layer disposed between the first and second partial reflectors.