Mathematical model of the exact fraction method for the order of interference

An improved method of interpreting the exact fraction method for the order of interference used in multiwavelength interferometry is examined. Optimal algorithms for choosing possible values of the integral orders of interference and a new, more exact method of calculating the result of two wavelength interference measurements are presented. The metrological problems of multiwavelength interferometry are shown to be closely related to the formalism of convergents of continued fractions in number theory.