Abstract: An optical interrogation system has camera arrays useful for determining the locations of a plurality of apertures on a flat tension shadow mask and fiducial marks on a screened front panel of a CRT. The system determines the actual location of apertures or fiducial marks with respect to the cameras' field of view. By eliminating gray scaling, the processing only for light/dark transitions in single-bit binary valued pixels from each of the cameras in parallel, i.e., simultaneously, remarkable rapidity is obtained in the interrogation of widely spaced fields with minimal hardware. The system may also be used to interrogate mask support surfaces on the front panel prior to welding the mask thereto.