Abstract: A system for changing the rate of a bit clock based on errors of individual facets of a rotating polygon utilized in laser scanning system, the errors that exist between facets causing the velocity of the scan associated with the facet to be different from other scans. Facet erros are detected initially by having a start of scan pulse initiate a bit clock counter which counts the clock pulses generated by a voltage controlled oscillator. The counter provides an output to an interval detector when a desired total bit count for a scan line is reached. At some time with respect to the counter output an end of scan pulse is generated. The interval between the counter output and the end of scan pulse is the error for a particular facet.Logic allows memory locations to be addressed and loaded with the errors produced by the remaining facets in sequence, the sequence being continually repeated as the polygon rotates.