MANUFACTURING METHOD FOR CROSS DICHROIC PRISM AND PROJECTION TYPE DISPLAY DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a manufacturing method for a dichroic prism by which a dichroic film can be placed with satisfactory planarity. SOLUTION: The cross dichroic prism which is the compound prism where two kinds of the dichroic films are placed to cross each other is mainly used as a color composition optical system of R (red) light, G (green) light, and a B (blue) light. First and second prisms being a rectangular parallelepiped prism, respectively, have almost identical square cross sections and side surfaces perpendicular to the cross sections. A first joint member is obtained by joining the side surface of the first prism and the side surface of the second prism across a first color reflection dichroic film so that a first projected surface and a second projected surface are formed at both ends of the prism having a relatively longer side surface among the first and the second prisms.