Abstract: An optical unit for inspecting the soldered surface of a printed circuit board incorporates a thick-walled translucent concave diffuser dome with a hollow central cavity facing the surface under inspection, lamps directing illumination on the exterior of the dome, inspection portals spaced around the diffuser dome for video camera inspection of the board surface, and X-Y maneuvering control means governing the relative scanning repositioning of the board surface and the dome. A light baffle between each camera and its inspection portal, incorporating alternately white and black conically chamfered rings, produces improved imaging of the inspected surface, and a flexible translucent skirt extending from the dome rim to the inspected surface, preferably formed of a large plurality of white plastic bristles, blocks direct illumination and assures substantially uniform diffused illumination of the inspected surface.