Colored light synthesis element and projection device therewith

The invention includes a first incidence plane, a second incidence plane, a third incidence plane, a first synthesis plane and a second synthesis plane that are interiorly orthogonal to each other. The first synthesis plane reflects light of a first color component that enters the first incidence plane, and transmits light of a second color component that enters the second incidence plane, having the first color component and the second color component, at least a portion of which has the same color component, and light of a third color component that enters the third incidence plane. The second synthesis plane reflects the light of the third color component that enters the third incidence plane, and transmits the light of the first color component that enters the first incidence plane and the light of the second color component that enters the second incidence plane. The light that enters the first, second, and third incidence planes is synthesized through the first synthesis plane and the second synthesis plane.