Portable optical contact angle meterUsing video appearance contour analysis method, measuring the contact angle between liquid and solid, measuring the surface energy of solid, applied in industries such as glass manufacturing, touch screen detection, circuit boards, etc. The portable optical contact angle meter is used to test the wettability of liquids on solids, that is, to determine the wettability of various liquids by measuring the size of the contact angle formed by various liquids on various solid materials. The method is to drop a liquid droplet on a solid horizontal plane and test the solid liquid gas three-phase boundary point on the surface of the solid. The angle formed by the two tangent lines of the gas-liquid interface and the solid-liquid interface sandwiching the liquid phase is called the contact angle.