Various embodiments may relate to an optical unit for a light-emitting structure, a light-emitting structure, and a light box comprising the light-emitting structure. The optical unit includes a body and a light-blocking structure, wherein the body includes at least one reflective surface, wherein the light-blocking structure includes a first light-blocking structure and a second light-blocking structure, wherein the first light-blocking structure is formed in one piece with the body, and the second light-blocking structure is arranged in the first light-blocking structure, wherein the first light-blocking structure is arranged to at least partially surround the reflective surface, to block the light leaks from the reflective surface by the second light-blocking structure.