Modular optical tensiometer for fully computer-controlled contact angle, surface and interfacial tension, dynamic contact angle and surface free energy measurements. Motorized and software-controlled sample stage with X-Y-Z movement. Drop samples placed at desired intervals to test any locations of one substrate. When combined with an automated dispenser and motorized vertical liquid dispenser motion, fully software-controlled measurements are possible. Motorized movement ranges: X = 180 mm, Y = 60 mm and Z = 30 mm. Movement resolution 0.01mm.