The Inspectron is an instrument which will perform an automatic optical inspection of the etched circuitry on the individual layers of a multilayer printed circuit board. The concept of this instrument is unique in that it does not compare the PCB under test with a master or with computer-stored data. Instead, as the board is optically scanned, a small area is re-imaged onto a detector array. The detector signals, after digitization, are fed into high-speed logic circuitry which is programmed to distinguish between the appearance of a good board and an error. An 8 x 10 inch board can be inspected for line width, line spacing, line breaks, excess copper, and voids in about a minute. The Inspectron can also inspect pads for completeness and ground planes for shorts.