Video probes are increasingly used in recent industrial applications of coordinate measuring machines, since they are found more efficient than conventional ball-tip probes especially in inspecting small-sized features of complex shapes. However, no thorough investigation has yet been accomplished to comprehend the measuring capabilities of video probes. In this dissertation, the measurement uncertainty of a video probe has been scrutinized by considering practical design parameters related to objective lens, coherence of illumination, defocus, aliasing of a CCD array, and edge detection algorithms. As results, a pragmatical uncertainty model has been proposed with the following conclusions:
(a) The uncertainty of a video probe is mainly affected by coherence effect of illumination and also by edge detection algorithms. On the other hand, defocus and aliasing produce no significant influences.
(b) Finally, an ultraprecision measurement of 0.01㎛ uncertainty can be practically achivable.
