Patent ID: 6407868
Filing Date: 2002-06-18
Classification: G02B

Abstract:
A method of making a cross dichroic prism, said cross dichroic prism comprising four triangular prisms having isosceles right triangular cross sections identical in shape, opposing side faces thereof being bonded and secured together with rectangular portions thereof facing each other; and a dichroic film having an X-shaped cross section formed between the bonding faces of said triangular prisms; said method comprising;a first step of preparing two prism members each having an isosceles right triangular cross section with a cross-sectional area twice as much as that of each said triangular prism; a second step of forming a first dichroic film on the hypotenuse face opposing its right angle of one of said prism members; a third step of forming a cemented member shaped like a regular quadrangular prism by bonding and securing the hypotenuse faces of said prism members together with an adhesive; a fourth step of cutting the cemented member at a plane which is orthogonal to said dichroic film and connects the opposing right angles of said two prism members, thereby forming two cemented members identically shaped like an isosceles right triangular prism; a fifth step of forming a second dichroic film on the hypotenuse face of one of said triangular-prism-shaped cemented members; and a sixth step of bonding and securing the hypotenuse faces of said triangular-prism-shaped cemented members together with an adhesive so as to form a prism having a cross dichroic film with an X-shaped cross section at a center thereof.