Abstract: A tester for electrical traces such as on a circuit board generally comprises an electromagnetic beam source such as a laser producing an ultraviolet beam, a vacuum chamber, an electrode circuit including electrodes and corresponding electronics including ammeters for measuring photoelectron flow between traces and electrodes, a controller, laser beam optics, an image acquisition system, and a pair of broadband UV lights. The board containing traces under test is disposed in the vacuum chamber at lowered pressure with grid electrodes lying close to the trace area on each side of the board. Electrode electronics selectively maintain a known potential on each electrode. The exact location of traces are determined by an image acquisition system. The board and traces are initialized to a known voltage. Photoelectric effect using ultraviolet laser beams is used to determine continuity between two points on a trace and shorts between traces.

Abstract: A tester (10), for testing electrical trace (90T) without electrical connection to test trace (90T), generally comprises an electro-magnetic source (25), such as a laser (26) for providing a beam (39) of electro-magnetic radiation, such as of ultraviolet light, directed on a single test trace (90T) for producing a photoelectric effect on test trace (90T) liberating electrons therefrom, a collector (50) disposed near test trace (90T) for collecting liberated electrons, and a collector circuit (60) electrically connected to collector (50) for supplying a positive potential thereto and including a meter (70) for measuring the photoelectric current to collector (50) from trace (90T).