Optical metrology · Software development · Image processing

Optical metrology · Software development · Image processing

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SURFTENS is a Windows image processing software for measurement of contact angle of liquids on solids. SURFTENS contains a calculation module for the surface free energy (SFE) from the contact angles of up to 5 test liquids.
SURFTENS software can be used in connection with OEG equipment, but also in connection with existing measuring setups at customer site.


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SURFTENS - download free demo version

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Technical background

The modification of the wetting ability of technical surfaces by special surface treatments becomes more and more common in industry and research. For process characterization, adjustment of technological parameters and production control it is therefore absolutely necessary, to measure the surface free energy objectively and accurately before and after the modification process. For this purpose a robust and easy to use contact angle measuring instrument is needed. SURFTENSuniversal was developed to meet the needs in industry and research The operation is simple and for everybody possible after a short training.

The manual operation ensures an attractive price.

Thus SURFTENSuniversal is used as well as in standard process control as well as in research and development.

In connection with the software »SURFTENS« the contact angle and the free surface energy of solids can be measured.

The comfortable documentation functions are a powerful help in quality assurance and research.

Accurate and fast measurement by image processing

Basically the measuring software »SURFTENS« makes possible the fully automatic measurement of the contact angle of a sessile drop by different fitting methods of the drop shape. The drop is automatically detected by image processing methods.

Specimen-dependent the contrast of the drop image can be critical for an automatic detection.

For such cases the software offers additional options for the drop detection like the manual setting of the baseline and the completely manual measurement of the contact angle by setting of measuring points on the monitor.

The scope of services is extended by additional measuring and service functions like:

real time display of current contact angle at the live video image,

automatic measurement of the time dependent contact angle and display in diagrams (cycle time freely selectable, minimum cycle time 50ms),

measurement of advancing- and receding-contact angle at the live video image,

simultaneous measurement of left- and right-side contact angle,

measurement on curved surfaces with angular baseline,


The software contains an evaluation module (theory by Wu) for computation of the free surface energy of solids from the measured contact angles of 2 known measuring liquids.By special software functions the drop volume is reproducible by 0,1 µl also with a manual dispensation system. As additional option the drop volume can be measured by the software.

A very useful feature is the acquisition of AVI-files from the live video stream. All measuring- and documentation functions are afterwards applicable to the complete film or any single image of the film.

The measuring results can be stored comfortable in protocols or the video image.

SURFTENS-measuring accuracy

The measuring accuracy is determined by using the live video image. A real drop of liquid changes itself permanently because of environmental influences like evaporation. Therefore the accuracy can be specified only by help of a contact angle standard.

The software has the following parameters:

resolution of contact angle measurement: 0,05°

reproducibility of contact angle measurement: ± 0,1°

accuracy of contact angle measurement: ± 0,5°

SURFTENS PD: additionally software module for measurement of surface tension of liquids

An optional extension is the software SURFTENS PD.

This software measures the surface tension of liquids using the pendant drop method.

The SURFTENSuniversal - standard configuration is sufficient for this measurement. Only the additional software module is necessary, which is offered as bundle in connection with the standard software.