Abstract: To overcome limitations of current optical inspection methods of integrated circuit boards, a new method of inspection is provided. A portion of the board being tested is illuminated at an oblique angle with a beam of coherent or collimated light. Furthermore three methods of detecting faults on integrated circuit board are presented, each which increases the utility of optical inspection of integrated circuit boards. The three methods are: 1) the use of diffraction of light to detect certain types of soldering faults: 2) the use of shadows to identify the presence or absence of components on an integrated circuit board: and 3) the direct illumination of components and parts of components. In addition, an innovative device for the illumination of integrated circuit boards is provided.