One embodiment of a micro-electronic device includes a substrate including micro-electronic components thereon, and a cover including a ring of sealing material secured to the substrate and a raised ring of material positioned opposite the cover from the ring of sealing material. This makes it possible to change a depth of field and observe an image magnified under an equal magnification focused in the depth direction on the monitor. A sliding element is inserted behind the clamping element in a guide running transversely to the aperture.