PURPOSE: To substantially prevent the generation of peeling and to allow the use under severe environment of a high temp. and high humidity by executing the irradiation to a substrate with UV rays between a substrate molding stage and a constituting element forming stage in a vacuum.
CONSTITUTION: This medium consists of the substrate 1 and the constituting elements 2 to 4 formed in a vacuum on the substrate 1. The irradiation to the substrate 1 with the UV rays is executed between the substrate molding stage and the constituting element 2 to 4 forming stage in the vacuum. Namely, only the extreme surface of the substrate 1 is decomposed by irradiating the substrate 1 with the UV rays, by which the bond with the layer 2 provided thereon is intensified. The substrate material may be plastics, such as acryl, polycarbonate and epoxy or may be glass in this case. The constituting elements to be directly provided thereon are in many cases a protective layer 2, for the constituting elements of which ceramics, such as silicon oxide, silicon nitride and zinc sulfide or the composites thereof, etc., are used. The peeling is substantially prevented in this way even in the severe environment of the high temp. and high humidity.