PRODUCTION OF CROSS DICHROIC PRISM

PROBLEM TO BE SOLVED: To easily obtain a cross dichroic prism with good accuracy by providing the process with stages from a first stage to an eighth stage which are respectively specific. SOLUTION: Transparent optical prism members 11, 12 are prepd. in the first stage. Both of the members 11 and 12 are optically polished on one side of the slopes holding the bases of rectangular parts and the rectangular parts thereof therebetween in the second stage. The dichroic film having a first light reflection characteristic is formed on the base of the members 11 in the third stage. The first dichroic film forming based for light reflection and the bases formed with notching by polishing of the members 11 and 12 are joined to manufacture the joint member in the fourth stage. The joint member is cut at the plane perpendicular to the joint surfaces of the members 11 and 12 of the manufactured joint member in the fifth stage. The tangent cutting plane of the manufactured first and second joint members is ground and polished in the sixth stage. The second light reflection dichroic film is formed on the one base of the first or second joint member in the seventh stage. The second light reflection dichroic film and polished surface of the bases of the first and second joint members are joined in the eighth stage.