Investigation on the aspects influencing the accuracy of a simple and affordable image-based system for liquid thin films monitoring

The paper focuses on the issues connected to the measurement of thin films characteristics, which is a crucial aspect in various technological processes. It ensures the efficiency and reliability of materials and machines. A low-cost and scalable image-based solution is used in laboratory conditions, to exploit the versatility of optical systems - already widely spread in many industrial contexts. The goal is to evaluate some characteristics of liquid thin films, namely the coated area and the film thickness, often utilized as an input parameter for analytical and digital models, to enhance the quality of processes or products. Concerning a predetermined quantity of common lubricant deposited onto the surface of flat panels of metal alloys, a preliminary experimental campaign has been conducted. The images have been processed and analyzed by means of a tailored algorithm, developed suitably for the specific tasks. The preliminary investigation confirms some of the key factors influencing the variability of the results, (i.e., camera adjustment and positioning, lighting conditions and algorithm parameters), and highlights a strong correlation with the material surface finish of the inspected specimens. A preliminary quantitative evaluation is also provided in terms of the area covered by the lubricant and average thickness, creating the groundwork for further comparisons.