Coating thickness measurement technology --- Profile Gauge method and light cut method

1) Profiler method 

The profilometer method, also known as the angle-out needle method, uses the method of shielding the sample before coating or dissolving after coating, so that a certain part of the substrate is removed from the coating, and a step is formed between the substrate and the coating. The thickness of the coating is obtained by measuring the height of the step through the probe movement of the profiler. This method can measure a wide range of coating thickness. It can measure various coatings ranging from 0.01 to 1000µm, and the accuracy is within ±10%.

There are two types of profile Thickness Gauges: electronic Recorder and surface profile Recorder.

2) Optical section method  

Optical sectioning is also called interference microscopy. The preparation of the sample is the same as that of the profilometer thickness measurement method, that is, a step between the substrate and the coating is formed, and the height of the step is measured by a multi-beam interference microscope, and then the thickness value of the coating is obtained. This method can measure various coating thicknesses below 2µm with high reflectivity.

The thickness of the coating is measured by the optical section method through an interferometer, a lens attached to the sample as a plane reference plate, when a beam of monochromatic light is reflected back and forth between the above sample and the lens, it can be observed that The image of the interference band generated between the optical plane and the surface of the sample, if the reference plate is slightly inclined relative to the surface of the coating to be tested, the image of the interference band will alternately appear as parallel light bands and dark bands, when the interference band is at At the step between the substrate and the coating, the image of the interference zone will have a relative displacement, and the displacement is the absolute amount of the potential difference between the sample surface and the optical plane. Therefore, the interference zone is observed and measured through a micrometer eyepiece and an interference microscope. With high displacement distance, the thickness value of the coating can be measured. For the use method of the interference microscope, please refer to the instruction manual of the instrument. (Related Instruments: Thickness Gauge)