Thin film colorimetric interferometry

Spherical rollers were machined from AISI 52100 steel, hardened to a Rockwell hardness of Rc 60 and manually polished with diamond paste to RMS surface roughness of 5 nm. Two glass disks with a different thickness of the silica spacer layer are used. For thin film colorimetric interferometry, a spacer layer about 190 nm thick is employed whereas FECO interferometry requires a thicker spacer layer, approximately 500 nm. In both cases, the layer was deposited by the reactive electron beam evaporation process and it covers the entire underside of the glass disk with the exception of a narrow radial strip. The refractive index of the spacer layer was determined by reflection spectroscopy and its value for a wavelength of 550 nm is 1.47. 

Hartl, M., Kfupka, I., and LiSka, M., Experimental Study of Boundary Layers Formation by Thin Film Colorimetric Interferometry," Sci. China, Ser. A Math., Phys., Astron. Technol. Sci.,Vol. 44(supp), 2001,pp. 412-417. 

In this paper the Thin Film Colorimetric Interferometry (TFCI) technique [11] is used for the film thickness mapping in mixed EHD point contact formed between a real, random, rough surface, steel ball and a smooth glass disc. The main aims of the work are ... 

The experiments reported here make use of the Thin Film Colorimetric Interferometry technique for film thickness measurement. In this technique, 3 X 8 bit SXGA still pictures are after transformation from RGB to CIELAB colour space converted to the film thickness map using appropriate colour/film thickness calibration curves. They are obtained from Newton rings for static contact formed between the steel ball and the glass disc coated with the chromium layer only. During several last years the accuracy and resolution of TFCI has been improved and it is now able to measure film thickness to within 1 nm [13]. 

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