US Patent 12019241 2D-pupil expansion light guide assembly

A light guide includes a first and second transparent monolithic optical parts (TMOP). The first TMOP has a first surface having two sets with one flat surface followed by one prism array. Each flat surface has a partially-reflective coating, and the first TMOP has a flat opposite second surface. Each prism array has two prisms having a first and a second surfaces which are oblique to each other and to the first TMOP's opposite second surface. The prism arrays first surfaces have a partially-reflective coating. The second TMOP has a first surface with a geometrically complementary shape relative to the shape of the first TMOP's first surface, and has a flat opposite second surface. The first and second TMOPs are assembled together using an optically transparent adhesive material, such that the second surfaces of the first and second TMOP of the light guide assembly are parallel to each other.