Television flaw detector for inspecting the wall surface of a hole through a circuit board

A television flaw detector, and process, for inspection of the wall surface of a hole through a circuit board. The circuit board is positioned on a support beneath a microscope, with the hole to be inspected aligned with the microscope. On the opposite side of the circuit board are an optical condenser and a light source. The condenser directs a divergent conical beam of light into the hole to illuminate the wall surface of the hole about its entire circumference and along its full length. A mask prevents non-reflected light rays from passing directly through the condenser and the hole into the microscope. A television camera mounted on the microscope is connected to a television monitor upon which it produces an image of a region of the wall surface of the hole extending from its full circumference at a selected position along its length.