Image geometric accuracy in large format color separation quality writing engines or
output scanners requires careful control of the opto—mechanical alignment of engine
subsystems. Internal drum scanners are particularly sensitive to misalignment of
the spinner, drum and spinner linear transport axes relative to each other.
Misalignment of these axes leads to significant errors in cross—scan and in-scan
pixel placement in the written image.
A method is presented for determining alignment sensitivity of internal drum output
scanners by tracing only the principal ray through the system and systematically
manipulating engine component axes with the ray trace model. The model traces
deviated rays through the misaligned system providing data on placement of pixels in
the written image. This method provides an efficient means of determining system
sensitivity to various alignment conditions and allows system tolerances to be