Mixed metal aluminum nitride and boride diffusion barriers and electrodes for integrated circuits, particularly for DRAM cell capacitors. At this location in the reservoir, which can be determined by appropriate calculation, the injection is stopped and the intermixed and superimposed chemicals are allowed to react to form the filtersieve of a gel or polymer depending upon the nature of the individual chemicals injected. The rigid foamed plastic carrier plate is provided with a pore-free sealed surface that facilitates sterilization. The positioner preferably allows translation andor rotation of an imaging device within the viewing tube within two perpendicular planes oriented along the axis of the viewing tube, thereby allowing the imaging device to view an area of interest from more angles oriented about the area of interest than would otherwise be possible if the imaging device was situated outside the vacuum chamber. Thereby, cooling can be carried out most suitably for each color optical path, and cooling that is superior in efficiency and in balance can be carried out.