The surface topography of a component part can have a profound effect on the function of the part. It is estimated that surface effects cause 10% of manufactured parts to fail. In tribology, it is the surface interactions that influence such quantities as friction, wear and the lifetime of a component. In fluid dynamics, it is the surface that determines how fluids flow and it affects such properties as aerodynamic lift, therefore, influencing efficiency and fuel consumption of aircraft.

Surface profilometry techniques such as coherent scanning interferometry or focus variation require long scan times and are thus vulnerable to environmental disturbance. For this reason, quality control of precision surfaces is done offline in a metrology lab, and only on a small percentage of parts produced. Hyperspectral interferometry (HSI) overcomes the problem by recording all the spatial and spectral information necessary to reconstruct a 2D surface height map in a single shot. In this project we developed a vibration-proof single-shot HSI approach, to enable the testing of all products in a production line. Tribology, optical surfaces, additive manufacturing and thin films, are some example applications.

The approach consists of a broadband source (superluminescent diode), a Linnik interferometer at the input of a pinhole array based hyperspectral imaging system and a large area photodetector array. The system lateral resolution is 370um, height resolution 100nm and depth range 0.88mm.

The system can provide surface area profiles with a lateral resolution of 370um, height resolution 100nm and depth range 0.88mm. 900 to 2500 independent channels have been demonstrated. It is also able to measure surface local roughness Sa parameter (validated with CSI).