A scatterometer operating at millimetre and sub-millimetre wave wavelengths

A scatterometer operating in the bands from 50 to 750 GHz has been designed and fabricated. Operation in the different bands is achieved by using a Network Analyser with appropriate frequency extenders and corrugated horns. The beam is propagated using reflective quasi-optics on two levels with the sample being mounted on the lower level. The two levels are connected by a rotating periscope which collects the scattered radiation from the sample and transfers it to the upper level where the phase and amplitude are measured by the Network Analyser. The scatterometer can measure in both reflection and transmission and in VV, HH, VH and HV polarisations. During a measurement the Network Analyser heads and associated cables remain static to prevent drift. Rough reference samples have been developed for testing the scatterometer and preliminary results are reported in the 50–75 GHz band.