Fast measurement of coating thickness with chromatic sensor

The thicknesses of coatings that can be penetrated with light from the visible to the infrared range can be measured with the Chromatic Focus Point point sensor, the Chromatic Focus Line line sensor and the multisensory Chromatic Focus Zoom (patented optical probe head with integrated image processing and chromatic distance sensor). With the CFP and CFZ point sensors, the coating thickness can be measured specifically at various positions on the workpiece or as a contour scan with high point density on the entire workpiece surface. The line probing of the CFL results in speed advantages in the measurement compared to CFP and CFZ. The volume between material borders can also be calculated.
With the interferometric principle, the measurable coating thickness range is between 5 μm and 150 μm when using visible light, and between 30 μm and 10500 μm when using infrared radiation. With chromatic measurement, in addition to “in the image” measurements in the measuring range of the sensor, i.e., without movement of the machine axes, the measuring range can be enlarged by “on the image” measurements with corresponding readjustment of the machine axes. The measurement results are dependent on the refractive index of the materials, so this should be known very precisely. Another possibility is the direct calibration of the coating thickness using other metrological methods such as Werth Fiber Probe® or computed tomography.

Typical applications for coating thickness measurement are thin glass plates, foils, air gaps, paint thicknesses, protective coatings on electronic components, wafers, membranes of loudspeakers or balloon catheters.