Three prism color separator

Abstract

Abstract A color separator using three joined prisms for color separation in projection displays. The configuration is compact, relatively simple to assemble, and eliminates a requirement for complicated optical components such as crossed dichroic beam splitters and large retrofocus projection lenses. The configuration is particularly advantageous for projectors based upon liquid crystal, reflective light valves or spatial light modulators (SLM). A first prism has a dichroic coating on an interface between the first and a second prism which reflects one primary color and transmits the other two primary colors. The light path through the first prism has a second reflection (total internal reflection) off the side of the first prism, and emerges normal to the third face of the first prism to a first SLM. The second prism has a dichroic coating at an interface of the second and a third prism which reflects one of the remaining two primary colors and transmits the third primary color. The second primary color is reflected toward the third face of the second prism and emerges normal to that surface to a second SLM. The third color passes through the third prism without any reflections and emerges normal to the surface of the third prism to a third SLM. The three prisms are optically contacted and cemented to one another at a first interface between the first and second prisms and at a second interface between the second and third prisms to form a single unit.

Inventors

• 👤 Fuad Elias Doany

Bibliographic Details