Ultra-wide range non-contact surface profilometry based on reconfigurable fiber interferometry

Surface characterization is essential for a technical evaluation of device performance and to assess surface dynamics in fabrication units. In this regard, a number of surface profiling techniques have been developed that accurately map sample topography but have significantly limited detection range. Here, we demonstrate a cascaded non-contact fiber interferometer-based approach for real-time high-precision surface profiling with ultrawide detection range (nm to mm). This compact interferometers' system operates by wavelength interrogation that provides a scope to study several types of surfaces and has a tunable cavity configuration for varying the sensitivity and range of the detectable features' size. The proposed system enables nanoscale profiling over 10-1000 nm with resolution of 10 nm and microscale mapping over 1-1000 µm with resolution of 0.2 µm. The technique is utilized to map the features of nanostructured surfaces and estimate the surface roughness of standardized industrial samples.