Patent ID: 8334887

Claim:
An image forming apparatus comprising: a photosensitive surface; a raster output scanner including a first optical emitter configured to scan a first beam across the photosensitive surface and at least one second optical emitter configured to scan a second beam across the photosensitive surface to form an image on the photosensitive surface; an integrated scan detector configured to detect the beams from the raster output scanner and configured to produce a signal based on the beams detected from the raster output scanner; and a beam calibration controller coupled to the integrated scan detector, the beam calibration controller configured to determine at least one beam delay between the first optical emitter and the at least one second optical emitter based on signals from the integrated scan detector, and configured to delay operation between the first optical emitter and the at least one second optical emitter based on the at least one beam delay, wherein the beam calibration controller is configured to determine at least one beam delay based on at least: d i = ∑ j = 1 N ⁢ Δ ⁢ ⁢ c i , j · T CLK · f pix N where i is a beam interval index corresponding to the total number of optical emitters, where d i is the delay corresponding to an i th optical emitter, where N is a number of samples, where Δc i,j is a difference between a time interval for the first beam and a time interval for an i th beam for the j th sample of the number of samples, where T CLK is an interval clock period, and where f pix is a pixel frequency for a given beam direction assembly speed.