Techniques are disclosed for fabricating optical instrumentation. This is followed by depositing a dielectric passivation layer over the entire wafer and defining a second lithographic pattern coincident with or slightly inset from the boundaries of the previously defined metal gate layer. The cover is unitarily formed and receives the printed circuit board. It is movable relative to the vaporizer between a first position operably coupled to the vaporizer and a second position spaced apart from the vaporizer.