
A grating (22) of narrow parallel ridges (24) is formed in the surface (26) of a substrate (20) made of a hard material such as silicon dioxide. Metal (40) is deposited onto the grating (22) perpendicular to the ridges (24) at an angle of approximately 45.degree. to the surface (26) of the grating such that the metal (40) is deposited onto the top (24a) and one of the sides (24b) of the each of the ridges (24) to form generally L-shaped metal strips (12') thereon. The metal strips (12') are cut ...











