Optical measurement of oil slick thickness using active interferometry

Abstract Spills of liquid petroleum hydrocarbons are a growing concern worldwide, posing great risks to marine life and community services. Identifying and treating oil spills is operationally and scientifically challenging and compounded by the difficulty in accurately obtaining real-time measurements of the oil thickness slicks. Here, we present a method that allows precise real-time measurement of oil slick thickness, based on active optical interferometry. A series of laboratory experiments with common hydrocarbon pollutant types, namely crude oil and gas condensate, showed that our method yields precise thickness measurements for slicks in the thickness range 0.382 - 23.3 (μm), with an accuracy of 95%. The novel oil layer thickness measurement system can in principle be adapted for use at sea, which would open the way for real-time thickness measurements that will improve oil-spill mitigation efforts and contribute to our understanding of processes at the ocean-atmosphere interface.