Surface profilometry with a fibre optical confocal scanning microscope

Differential confocal microscopy (DCM), a non-interferometric profilometry, is first extended to be used in a fibre optical confocal scanning microsco pe (FOCSM) system. Errors of DCM in a FOCSM system are theoretically analys ed in detail. Analytical results show that the optimum system parameters sh ould be chosen in order to keep the measurement error low and the profilome try efficient. Experimentally, the surface of a reflection grating was meas ured with nanometre depth resolution. In addition, we develop DCM to determ ine the surface heights of inhomogeneous samples. The approach is used to p rofile the surface of a coated compact disk and the overlay structure of a test bar. The experimental result also shows that, for measurement of the s urface of a sharp edged sample, the approach will be an alternative techniq ue for use to generate an edge enhanced profiling image.