Thin film thickness calculator 

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This tool calculates the thickness of your transparent thin film from the interference peaks and valleys.

How it works
At any extrema we know that the reflections from the front and back of the thin film are either exactly in phase or out of phase. The phase shift between the reflections from the front and back of the thin film is
ErrorsIn the solution of these simultaneous equations we end up using a difference between two wavelengths. So even if we know the wavelengths accurately, the errors in the differences can be significant. For example if we have a minimum at 500nm +/ 2nm and a maximum at 525nm +/ 2nm. The accuracy of the minimum measurement is 2/500 = 0.4%. But the error in the difference is +/ 4nm in 25nm, that is an accuracy of 4/25 = 16%. So this is not a precise method of deriving thin film thickness, and to get a reasonable thickness value several extrema values should be used. 