A method of producing a prism comprising a first prism component and a second prism component that are joined together along a partial reflection plane that is inclined with respect to the optical axis. The method has steps comprising measuring the refractive index for multiple base materials constructing the first prism component and the second prism component and joining the base materials having approximately the same refractive index measurements together along a partial reflection plane in such a manner that the refractive index measurements are associated with specified positions during the course of joining.