Here's an interesting patent from Japan's Nikon Corp.
Color separation device of solid-state image sensor
A microlens condenses incident light to an opening. Light passed through the opening reaches a first dichroic mirror. The first dichroic mirror passes blue light and reflects green and red light. Only the blue light is incident on a first light receiving surface. The first dichroic mirror leads the green and red light to a second dichroic mirror. The second dichroic mirror passes the green light and reflects the red light. Only the green light is incident on a second light receiving surface. The second dichroic mirror leads the red light to a third dichroic mirror. The third dichroic mirror reflects the red light. Therefore, the red light is incident on a third light receiving surface.
Inventors: Hoshuyama; Hideo (Kawasaki, JP)
Assignee : Nikon Corporation (Tokyo, JP)
Appl. No. : 10/732,462
Filed : December 11, 2003