Nanometrology of sub-wavelength circular holes in gold nanofilms using optical surface profilometry

Optical surface profilers are useful metrological instruments, however their application to nanometrology is hindered because ray-optic approximations are included in the physical model that relates measurand (irradiance profiles) to the height profile of the object surface [1-2]. Using optical surface profilometry for nanometrology is an attractive prospect because they are compatible with conventional optical systems, enabling in situ nano-characterisation of single particles to be performed in conjunction with other advanced optical microscopy techniques. In addition, optical surface profilers are capable of rapid measurement and require no sample preparation, allowing nano-characterisation to be performed with speed and flexibility in the laboratory.