  We report on a traceable calibration system for a 3500mm-long console that
carries a measurement system for inspecting the diameter of a circular reactor
chassis. The system uses two single-pass laser interferometers with homodyne
fringe detection for measurement in two degrees of freedom. The hybrid
FPGA-microcontroller control module carries out the fringe detection together
with the application-specific scale linearization approach and the compensation
of environmental influences such as thermal elongation and the refractive index
of air fluctuations. We demonstrated the system feasibility with an accuracy of
a few microns and translation velocity higher than 0:1 metre per second.
