本视频中演示了采用Young-Laplace方程拟合时各家接触角仪公司软件的区别。从测试结果来看，接触角变化范围从103－105度之间，属于一个合理的变化范围。这种变化由各种因素造成，如水的挥发等。

另可参考如下资料，我们发现国外的部分生产厂的接触角仪软件使用Young-Laplace拟合时，90－140度时，测值偏大5度，而大于140度时，测值偏大约10度。

We measured contact angle of same sample with 4 different software from Kruss, Dataphysics, Biolin and KINO. And we measured contact angle of sample by Biolin's sofware - OneAttension V2.4 at first because only this software cannot import images into software and calculate contact angle for imported image. Other sofwares such as DSA1.92 and DSA3.0 from Kruss, and SCA202 from Dataphysics and CAST3.0 from KINO can all import image into software and can calculate contact angle using different method such as circle fitting method, ellispe fitting method and Young-Laplace equation fitting method.

At this article, we just show you the calculated result by different company's software. Comparison of measured result maybe has some existed deviation due to our misoperation. You can contact us to obtain the recorded video for measuring process of contact angle.

And from the comparison of measured contact angle from different drop shape software, may safely draw a conclusion that:

1, When contact angle below 3°:  anti-dazzling screen must be used to get sharp drop shape and when using Young-Laplace equation fitting method, only sofware from Biolin (OneAttension V2.4) is failure to fitting the drop shape and get a acceptable contact angle.

2, When there exists some noise points or poor backgroud, tangent method based on parts of drop profile will  failure to fitting the drop shape and get a acceptable contact angle.

3, When contact angle between 90°-140°, calculated contact angle based on Young-Laplace equation fitting method from drop shape analysis software from Kruss, Dataphysics and Biolin will be larger than other mehod such as circle fitting and ellispe fitting about 3-5° when circle fitting or ellispe fitting can fitting the drop shape. And also this value based on Young-Laplace equation fitting method is larger than ADSA-RealDrop based method from KINO about 3-5°.

4, When contact angle larger than 140°,  calculated contact angle based on Young-Laplace equation fitting method from drop shape analysis software from Kruss, Dataphysics and Biolin will be larger than other mehod such as circle fitting and ellispe fitting about 8-10° when circle fitting or ellispe fitting can fitting the drop shape. And also this value based on Young-Laplace equation fitting method is larger than ADSA-RealDrop based method from KINO about 8-10°.

5, Calculated ontact angles by different method from KINO's sofware CAST3.0 are almost kept same when both of them fitting drop shape correctly.

 Please be noted that,

1, A basic principle is contact angle is calculated from tangent at contact point or curve radius at contact point. And when fitting drop profile with some equation of curve, if result of fitting is good, calculated contact angle will be almost same. In other words, Young-Laplace equation can be used to calculate contact angle when drop shape cannot fitting with circle equation due to effect of gravity. But if we used other equation of curve and fitting it correctly, the result will be kept almost same.

2, Red number means it is failure to fitting drop profile with current method. And "—" means current method cannot calculate any result automatically.