Measurement of fiber diameters with high precision

摘要: Methods for measuring the diameters of transparent filaments with high precision, e.g., RMS standard deviations less than 0.02 microns, are provided. The methods involve determining average spatial frequency ω far-field interference pattern produced by illuminating filament a beam laser light. is determined performing fast Fourier transform (FFT) on data to obtain coarse estimate and then set discrete sequence transforms (DSFTs) in region desired precision average. Efficient on-line processing procedures provided so that real time measurements can be performed on, example, moving optical waveguide fiber, at rates 500 measurements/second above.