Conic section method

Method for determining the contact angle in drop shape analysis. With the conic section method, it is assumed that the shape of the sessile drop describes an elliptical arc on the surface.


The parameters of a conic section equation are matched to the optically determined drop shape. Lines, which pass through the points of intersection of the arc with the baseline (three-phase contact points), are drawn tangentially to the elliptical curve calculated in this way. The contact angle is determined on both sides as the angle between these tangents and the baseline.

As a rule, the real drop shape is described more accurately than with the methods which start from a circular contour (height-width method and circle method).