A new image analysis algorithm for contact angle measurement at high temperature

Abstract

In recent years there has been considerable progress in automated techniques for measuring basic parameters characterizing interfacial interaction. However, the existing automated measurement systems can only measure properties of selected materials in a narrow temperature range. Also, the existing image processing and analysis algorithms are sensitive to interference and require precise positioning of the specimen. It is particularly difficult to use the algorithms to measure the specimen at high temperature, because the quality of acquired images is affected not only by the imperfection of the vision subsystem but also by the distortion due to the flow of protective gases. This paper presents a new image analysis algorithm, which has been developed for fully automatic measurement of the contact angle in a wide temperature range for a variety of materials. The measurement is based on successive approximation of the specimen edge with ellipses. The algorithm has been implemented in a system, which can measure surface tension and wetting angle, and tested in a wide temperature range for a variety of specimen materials. This algorithm has a number of advantages over the existing ones, in particular immunity to the shape, size and location of the specimen and low computational cost. The obtained results are independent of the subjective assessment of the measuring system operator with high reproducibility.