This paper describes common efforts of Warsaw University of Technology and Polish Central Office of Measure to build
a multiwavelength interferometer with extended measurement range to calibrate long gauge blocks. To achieve this goal
modified automatic fringe pattern analysis method based on fringe fraction method is proposed. The setup with special
chamber with active temperature control to stabilize environmental conditions has been build. To assure correctness of
measure factors like temperature, pressure, humidity and concentration of CO2 are need to be constantly monitored by
network of sensors. Summarizing all this efforts we are presenting gauge blocks calibration results with uncertainty
In the paper the multiwavelength interferometer with automatic data analysis based on phase fraction method is
described. It is used to extend measurement range without losing sensitivity, especially to calibrate long gauge blocks.
Numerical simulations and experimental work results have been shown to confirm proper functioning of this method.
However, stabilization of environmental conditions and light sources has significant influence on correctness of
measurement results. To match those requirements measurement system, which will be built for Polish Central Office of
Measures, has been designed. This design is based on Twyman-Green interferometer and assumes usage of two highly
stabilized laser sources. Optical and mechanical design of this system has been shown. Moreover, system for monitoring
and stabilization of environmental conditions is required.