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Wavelength-Shift Interferometry: Using a Dither to Improve Accuracy



Jack A. Stone Jr., Alois Stejskal, Lowell P. Howard


A dither in path length can dramatically improve the accuracy of wavelength-shift methods used for absolute distance interferometry. Here we report how a dither improves the accuracy of absolute distance measurement by two orders of magnitude, reducing errors from 1?mm to 10??m (1?s ). The dither is provided by modulating the position of a cube corner reflector in the reference arm of the interferometer. The modulation amplitude is on the order of 10??m, short relative to the synthetic wavelength associated with our wavelength-shift but much longer than the physical wavelength of our laser (670?nm). The effect of errors in our system that have periodicity of 1/2 wavelength can be largely eliminated by averaging results while modulating the path length.
Proceedings Title
Proceedings of American Society for Precision Engineering
Conference Location
Monterey, CA, USA


absolute interferometry, diode lasers, dither, interferometry, length measurement, wavelength-shift interferometry


Stone Jr., J. , Stejskal, A. and Howard, L. (1996), Wavelength-Shift Interferometry: Using a Dither to Improve Accuracy, Proceedings of American Society for Precision Engineering, Monterey, CA, USA (Accessed May 30, 2024)


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Created December 31, 1995, Updated October 12, 2021