Interference microscopy methods, contact

Two rather specialized methods are available to measure contact angles less than approximately 60". The method of interference microscopy makes use of fringe patterns reflected from the drop surface to calculate the contact angle [13]. Fisher [14] obtained contact angles less than 30 by simultaneously measuring the mass of the drop and the radius of the three-phase line. The contact angle was then derived from a semiempirical relationship involving these two quantities. 

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