Scan velocity variation in a flying spot laser scanner is a major contributor to pixel placement errors. Two sources of scan velocity variation are Motor Hunt and Polygon Signature. Since the incremental change in frequency needed to correct scan velocity variation may be very small, a highly accurate method is required to both measure the facet-dependent velocity differences and correct them.' An all-digital system which has the required high accuracy has been successfully demonstrated for the correction of these effects. The system employs a crystal time base and adjusts the frequency of a bit clock by fractional control of its phase. The accuracy of the measurements of the polygon characteristics is augmented by averaging many measurements.