A cover plate for covering an opening of a casing in which a solid state imaging
device is disposed. The cover plate comprises a transparent cover plate member
and a conductive film layer. The cover plate hermetically covers the opening of
the casing and the conductive film layer covers the outermost surface of the transparent
cover plate member. The transparent cover plate member is comprised of a plurality
of laminated transparent plates such as lithium niobate plates for an optical low-pass
filter and a plate for an infrared cut-off filter. An example of the conductive
film layer is a metallic film such as Cr or Au, coated on the surface.