CWL FT - High precision measurement of thin transparent films in the micrometer range


The CWL FT is an interferometric film thickness sensor especially designed to measure the thickness of products such as films or coatings that are transparent to visible light. With the CWL FT, the film thickness can be evaluated at a given position, along a profile or over the entire surface as a mapping to evaluate the coating homogeneity. In addition, the sensor is also suitable for the characterization of multilayer systems. FFT (Fast Fourier Transformation) can be used to measure layer thicknesses of up to two layers in the range from approx. 2 to 250 μm with a resolution of approx. 10 nm.

The CWL FT is based on the spectral evaluation of the superposition of partial waves of a white light source reflected at the interfaces of a transparent layer. At a given film thickness and refractive index, the intensity of the superimposed partial beams varies with the wavelength. The spectrum then shows a typical interference pattern. From this spectrum and the refractive index of the coating material, the sensor calculates the thickness.

The analysis program FRT Mark III is used to evaluate the measured film thickness. The powerful software is used in the FRT measuring tools to display and evaluate topography data as well as film thickness measurements.

The multi-sensor measuring tools of the MicroProf® series offer the possibility to combine the film thickness sensor with a chromatic distance sensor. This allows the film thickness measurements described as well as topography and profile measurements with a height resolution of a few nanometers in one measuring tool. This provides you with an extremely powerful measuring tool for fast, highly accurate film thickness and topography measurements.

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