CHARACTERISTICS OF IMAGE DATA-PROCESSING TECHNIQUES FOR SESSILE DROP METHOD

Both profile fitting and curvature plotting methods have previously be en submitted as new image processing techniques in the sessile drop me thod by the authors. The purpose of this research is to elucidate the characteristics and the applicable limits of these data processing met hods (including the traditional Bashforth and Adams method) and in tur n submit a guide to their choice. Both theoretical sessile-drop profil e as a solution of Laplace equation and sessile drop profile from the present experiment are processed by the above methods. As a result, th e precision and the optimal applicable range of these methods are disc ussed. The results obtained are as follows. (1) Under the present proc essing conditions, the precision of the profile determination is estim ated to be +/-1.3 mu m. This value is comparable to that obtained with an optical projecting magnifier which is usually used in the traditio nal Bashforth and Adams method. (2) The error in the data processing t hrough the use of the profile fitting method is determined to be less than 0.1%, independent of the number of profile data points (more than 130 points). (3) The precision of the presumed beta-value, which was defined by Bashforth and Adams, by the curvature plotting method is de pendent on the number of profile data points definitely. However, the curvature plotting method is optimal in order to inspect a local littl e change in the sessile drop profile. (4) The traditional Bashforth an d Adams method is very simple and requires only a few measuring points . However, it is apparent that the confirmation of fitting of an exper imental profile with a recalculated profile from the obtained beta-val ue is indispensable. (5) The surface tension of an Au20 at%-Ag80 at% a lloy at 1375.15 K in Ar-7 vol%H-2 atmosphere was determined to be 914. 0 mN/m. This value was in good agreement with the reference data.