Gauge Block Measurement Using a Wavelength Scanning Interferometer

Abstract

A gauge block measurement system that uses a wavelength scanning interferometer was developed. By using a wavelength scanning technique, we determined the integer part of the interference fringe order. From that integer part, we determined the absolute length of a gauge block using only a single light source (wavelength scanning laser diode), even when no information on the nominal length of the gauge block was available. Using the Fourier transform technique to analyze the interference fringe, we measured the excess fraction parts of the interference fringe order with a resolution of over 0.003, and then we determined the integer part of the fringe order in the test measurement of a 10 mm gauge block. It was estimated that we could determine the integer part when the nominal length was shorter than approximately 100 mm, which can be expanded by improving the frequency stability of the light source. The final uncertainty was similar to that obtained with a conventional system based on a multiple wavelength interferometer.