Abstract: A three-dimensional triangulation-type sensor-illumination system adapted for connection to a machine vision computer. The illumination source in the preferred system comprises a unique cross hair light pattern which provides sufficient image data to the computer to enable the computer to make three-dimensional measurements of a wide variety of features, including edges, corners, holes, studs, designated portions of a surface and intersections of surfaces. The illumination source and sensor are both mounted within a single housing in a specific position and orientation relative to one another, thereby permitting the system to be internally calibrated. In addition, the sensor-illuminator unit is preferably mounted in a test fixture so that the light source is substantially normal to the surface of the part to be examined and the sensor is thereby positioned at a perspective angle relative thereto.