High precision measurement of meniscus profile on liquid column in cylindrical capillary based on telecentric imaging...

The precise characterization of capillary meniscus has been a measurement bottleneck in interface science for three centuries. The accuracy of traditional measurement methods is not only limited by perspective errors and refractive distortions, but also lacks effective precision closed-loop verification mechanisms. In response to this challenge, this paper applies the telecentric imaging technology to the detection of the meniscus profile, which avoids the perspective error of the traditional imaging system, so that the absolute accurate correction function of the meniscus profile in the cylindrical capillary can be derived without any approximation. The system error is verified by measuring the profile of the standard steel ball in the capillary, and the maximum relative root mean square error was 0.92%. Subsequently, the meniscus profiles of water, ethanol and glycerol in eight cylindrical capillary tubes with inner diameters of 0.84-5.05 mm were extracted based on the above measurement methods, and the arc fitting evaluation was carried out. The results show that the goodness of arc fitting of the meniscus profile under different conditions is greater than 0.99, and even greater than 0.999 under more than half of the conditions. Based on this, it is inferred that the cylindrical capillary meniscus is very likely to conform to the spherical surface, and its mechanical properties may be similar to the inverted hemispherical shell membrane model under uniform load. Further research on capillary phenomena may be inspired by relevant fundamental mechanics theories.